Whether you plan to mount an oil gauge on your bike permanently or not, it's a good idea to have one in line for heat cycles and engine break-in. Sure the oil light will come on if your running dry…or will it? A gauge will let you know that the oil pump is working/ pumping oil to your engine during initial start-up which is a crucial time to know especially if it's not.

• Heat cycling an engine upon initial start-up from a fresh build is a process of heating up and cooling down the engine’s internal parts in stages to help insure mating/ sealing of the piston rings to the pistons and cylinder walls. This is a much debated topic in which no actual proof exists or has been published to the nay-sayers of this practice. You won’t find it published in the FSM (some say that’s because it’s done at the factory before the bike leaves). ¹⁾
• Micro welding is caused by excessive localized heat created when new rings are wearing in on a freshly honed cylinder wall. The highest part of the ring touching the highest part of the wall will create localized friction and heat until the rings have seated completely. The primary consequence of micro welding is loss of performance due to poor ring to land seal caused by micro welding. Other consequences may also occur. ²⁾

• Heat cycling your engine in some form or another is published and condoned by cylinder manufacturers and is an integral part of their published initial startup procedures to help prevent micro-welding of the rings. Consequently, if you do not heat cycle upon initial startup, you may be leaving any warranty from them in the trash can.
  • Lugging or running engine prematurely at high rpms may result in damage to pistons and/or other engine components. S&S® voids its guarantee if engine is not broken in properly.

• More people recommend this procedure for EVOs, especially most cylinder manufacturers although some do recommend it for all engines as well.
  • EVOs have a cast iron lined, aluminum bodied cylinder which is sandwiched between the heads and the case with long bolts. The heat transfer differences in the different metals are of concern as they have different rates of expansion and contraction. Aluminum also deforms at a much lower tensile strength that iron, and also at a much lower temperature than iron. When you start an Evo, you've got a cylinder that “grows” at one rate, a liner that “grows” at another rate, and studs that grow at an even “different” rate. ³⁾
    • But, in discussing heat damage, aluminum has about 3X the thermal conductivity of iron. ⁴⁾

• Ironheads are a solid block of metal but the new rings even in a seasoned engine need to mate to the cylinders as mentioned.
  • Ironhead cylinders are 100% homogeneous ferrous alloy castings. The whole cylinder has the same rate of expansion and contraction and the cylinders bolt solidly to the crankcase . ⁵⁾
    • Neither new rings nor freshly honed cylinders are perfectly round. That means when you put them together, the rings are only touching the cylinder walls in a few places. The pressure gets concentrated in those spots. That makes the rings get very hot in those localized spots….. It's even more critical with full iron cylinders….There's nothing magical about the bike being an Ironhead that changes the laws of physics. ⁶⁾

• In theory, heat cycling also extends the longevity of your engine.
  • The faster the rings seat, the faster the heat transfer is controlled. During break in, the rings cut their way into the cylinder walls until fully mated all the way around. Since the rings and cylinders are not perfectly round, only various contact points are reached by the rings initially. These points become hot spots since the full ring is designed and needed to transfer the heat prescribed properly instead of just a few spots here and there. This is also true for a re-ring job as well. The new rings have to mate to the seasoned cylinders. These hot spots can lead to a condition known as micro welding.
    • All moving parts in an engine also have to mate together in the process of break in such as bearings, bushings, thrust surfaces, rocker arms, valves, etc. There are many factors that determine cylinder health and life and controlling heat is certainly high up there. The faster the rings seat, the faster excess heat from ring hot spots subsides. Of course there are other factors than just ring seat causing excess heat on startup like quality of machining processes used (boring, honing), engine oiling, quality of the build itself, quality of parts used, engine compression, engine timing, tuning, proper cooling and etc.
• The idea of heat cycles is to “wear down the high spots in a ”““controlled””“ manner. ⁷⁾
• It's an exercise to limit excessive temperature by limiting the amount of heat build-up during the first few minutes of operation as the rings begin to lap themselves in. ⁸⁾
• Like it or not, you are heat cycling every time you start a new engine, shut it off and let it cool before you ride it again. Therefore, it is impossible to not heat cycle a new engine. ⁹⁾
• An unfired rebuilt engine has all kinds of torsional, tensile, and compressive stress stored in its metal, I can't think of anything better for an engine than slow, progressive heat cycling as you break it in. If the same process aids in eliminating micro-welding, and it appears it would, all the better. ¹⁰⁾
• The heat cycle is good because you don't subject a new build motor to extreme heat. ¹¹⁾

• Ring seal and its effect on engine output cannot be overstressed. The rings have two sealing responsibilities: the cylinder wall and the piston groove. We have seen power jump significantly by replacing the pistons and rings and restoring the bore integrity. Sometimes the pistons looked fine but the ring lands had been damaged during break-in due to heat. ¹²⁾
• The idea of heat cycling is not to treat the metals, it's to give the rings a chance to carve the cylinders into their shape, such that the tension gets evenly distributed and you avoid hot spots. That's what ring seating is. Heat cycling and gentle break-in is all about preventing things from getting too hot until the seating occurs. ¹³⁾
• From S&S Cycle on a new S&S engine: For the initial startup, a baseline calibration for a T143 should be downloaded to the ECU (a base Powervision tune file is available from the S&S website) This is adequate for the initial start-up and heat- cycling of the engine. ¹⁴⁾
  • For S&S Stroker Kits:
  • Break engine in using following procedure: On initial engine startup, don’t just sit and idle motor while you admire your work, or tinker with minor adjustments. Heat buildup can be excessive. First 50 miles are most critical for new rings and piston break-in. Most engine damage will initially occur during this period. Keep heat down by not exceeding 2500 rpm. Vary speed. Do not lug engine.

• Revolution Performance website doesn’t mention anything about heat cycling although they may do it there before shipping. But, they ship their engines dry so that doesn’t sound like it’s been run. They do say this: After passing all of our quality tests, your engine is covered by our Limited Warranty. ¹⁵⁾
• From NRHS: Run the bike for 1 minute, then shut it down and let it cool completely. Then run it for two minutes and let it cool completely. Then repeat for 3 and 4 minutes while letting it cool completely between intervals. Next, take it for a 20 mile ride and let it cool completely. Heat cycles are now complete.¹⁶⁾

• Arguments against the practice of heat cycling range from builder’s ideas that:
  • General instructions are written for ham handed mechanics and do not apply to ‘real or good mechanics’, ¹⁷⁾
• Discounting the practice as:
  • Un-necessary and a waste of time for an ironhead ¹⁸⁾
• Never did before. Why now?:
  • I've rebuilt lots of engines and never heat cycled anything ¹⁹⁾
• Car engine manufacturers don’t do it:
  • My buddy worked at a gm plant for 30 years. He said they fire em up and give em hell. No gentle nothing ²⁰⁾
• It’s only relevant to EVOs:
  • The evos have very tight tolerances in comparison, if that is the issues in there break in cycles…… No heat cycles in Iron head here. NEVER ever had any issues. even in race motors. after running and moving up down in rpm cycles, after cool down just check bolts and torque / nothing out of ordinary. ²¹⁾
• It seems to me that any instructions for modern engines [S&S, Ultima, Evo, automobile, truck, snowmobile, boat, etc] do not apply to IronHead engines. ²²⁾
• It’s a maker’s CYA clause and nothing more: Heat cycling is made by lawyers to keep Business from having to replace stuff due to any number of issues. heh, IT was the lawyers that wrote the Warranty info after all… ²³⁾
• If you employ the most modern machines and best talented machinists, your cylinders will be perfectly straight, rings will automatically seal since the cylinder roundness perfectly matches the ring roundness:
  • Read my post in the importance of torque plates, honing finish and straightness of the bores…. What were acceptable machining practices 25 years ago, [IE honing plateaus, [roughness]], still followed today, will almost guarantee ring damage and a decrease in engine performance and running life…..it's not how you break it in..it's how the engine was built. ²⁴⁾

What’s the best way to break in a new engine?

• The short answer: Run it Hard! Why? Nowadays, the piston ring seal is really what the break in process is all about. Contrary to popular belief, piston rings don't seal the combustion pressure by spring tension. Ring tension is necessary only to “scrape” the oil to prevent it from entering the combustion chamber. The ring exerts maybe 5-10 lbs of spring tension against the cylinder wall …
  • How can such a small amount of spring tension seal against thousands of PSI (Pounds Per Square Inch) of combustion pressure? Of course it can't. How do rings seal against tremendous combustion pressure? From the actual gas pressure itself! It passes over the top of the ring, and gets behind it to force it outward against the cylinder wall. The problem is that new rings are far from perfect and they must be worn in quite a bit in order to completely seal all the way around the bore. If the gas pressure is strong enough during the engine's first miles of operation (open that throttle !!!), then the entire ring will wear into the cylinder surface, to seal the combustion pressure as well as possible.
    • The Problem with “Easy Break In” … The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the “peaks” of this roughness, regardless of how hard the engine is run. There's a very small window of opportunity to get the rings to seal really well … the first 20 miles! If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again. ²⁵⁾

• So far there seems to be a lot of evidence that micro welding of rings can occur and while there are many different “variables” in play here, the only safe assumption is it's best to be on the safe side with heat cycling and proper break-in. With different types of engines, machining, assembly practices needing more care at initial startup than others. ²⁶⁾
• And, once again, if your installing new cylinders and you require the warranty, do as the manufacturer asks you to. ²⁷⁾
• Heat cycling is more of a performance trick rather than a build standard. ²⁸⁾ And, in fairness to all, I might add that definition (while seemingly accurate) may be the root of the problem since it doesn't take a performance trick to make an engine run. While the fact that it may take a performance trick to make it run well is subjective to the builder/ owner especially without the smoking gun that everyone seems to be looking for. Without that smoking gun, a builder's belief and reason system is tested and not any builder I've ever met likes to change his opinions very easily, especially from things he's practiced for years.
• We all have our methods, techniques, and beliefs based on what we have experienced. That is a good thing, because it allows the creame to rise to the top. Nothing begats believers more than success. ²⁹⁾
• This is meant as an informative on the subject of heat cycling, nothing more and nothing less. ³⁰⁾

This topic is a compilation of several XLFORUM threads on heat cycling:

• http://xlforum.net/forums/showthread.php?t=1501831&highlight=heat+cycle
• http://xlforum.net/forums/showthread.php?t=1794806&highlight=heat+cycle
• http://xlforum.net/forums/showthread.php?t=1969636&highlight=heat+cycle

Manufacturers and Industries alike condone the practice of Heat Cycling as a deterrent against micro-welding. Micro-Welding between rings and pistons are not a myth. ³¹⁾ It is defined as adherence of sporadic particles of aluminum from the piston to the bottom side of the piston ring by SAE (Society of Automotive Engineers). ³²⁾) Several other things can also cause micro welding, such as improper taper on face of ring, improper ring tension, improper ring material, improper clearance, improper assembly procedures/specs and clearances, improper assembly lube, improper initial tuning, improper initial break in. Too much surface contact between a new ring and perfectly smooth bore can cause excessive friction and heat. ³³⁾ piston lands too high on pistons on HP engine, improper clearance between ring and groove in cylinder, or incompatible materials with different coefficient of expansions. Piston and or rings got too hot from lean AF mixtures, timing too advanced, getting them too hot too soon can also cause it. ³⁴⁾ The variables are so vast, even SAE concedes that because of the variables at large in normal settings, it is difficult to find the proof needed to get a better handle on the subject. ³⁵⁾ So, SAE did a lab test and produced micro welding in a six cylinder high output 2 stroke water cooled engine in 30 minutes with silicon aluminum pistons and treated ductile iron rings running at 5,200 RPM and no break in time using an accelerated bench test in 1996. ³⁶⁾ No other evidence of testing for micro welding of rings has been found to be done by SAE. Obviously, proper heat cycling will not prevent micro welded rings when a multitude of other problems exist. ³⁷⁾

• In breaking in a new bike, you might hear from other owners how they tested their rev limiters, rode it fast and hard for however many miles or purposely stayed in stop and go traffic to simulate heat and cooling cycles. Just follow the MFGs recommendations from your owner’s manual ³⁸⁾ and you’ll be fine. These are common instructions that are given to every new bike owner. It's just an easy way to say keep the heat down. ³⁹⁾
• Generally speaking, main thing is dont over rev it, dont under-rev and lug it and dont overheat it. ⁴⁰⁾
• An engine is said to be broken in by the first 500 miles by the MoCo. ⁴¹⁾but for the first 50 miles, keep speed below 45MPH. For the first 500 miles, vary your speed, avoid steady speed on long distances and keep it under 60 MPH. FSM and Clymer are pretty much in agreement on this paragraph.
• Proper warm up is also imperative. Along with proper break in and getting in the habit of allowing the motor to warm up properly before any ride will go a long way in giving you years of trouble free performance. ⁴²⁾
• Before changing exhaust and/or other mods that could change the air/ fuel mixture or exert different than intended pressures on the engine, break it in first, then pay your Harley tax. ⁴³⁾
• Change Oil during and after break-in. The motor will put lots of metal in the filter in the first couple of hundred miles. ⁴⁴⁾ Dino (mineral based) oil is the widely accepted type of oil for use in breaking in a new engine. You may want to change oil and filter several times during break-in if you like. It won't hurt anything but it's recommended after the first 500 miles. After the first 2,500 miles, you can swap to synthetic oil if you choose.
• Noises during break-in: Keep the little stuff adjusted and fluids topped off. Run a good brand of gas and keep the revs within a good range without bogging it. ⁴⁵⁾. Sportsters are noisy….If she sounds like a sewing machine with dual exhaust, you're fine. ⁴⁶⁾
  • There may be noises of the different parts trying to mesh together, lifters may be noisy until fully pumped up ,etc. If engine noises persist, see engine_noises in the troubleshooting section.

• When breaking in aftermarket cylinders, conversions, it's best to follow the manufacturer's procedure for breaking in their products to ensure the accompanying warranty from them. This information is usually sent along with your kit from them.
• Engine break-in has been described as “ the final machining process” and is an important part of ring sealing, performance and longevity of your engine. Most manufacturer's recommend to heat_cycle the engine first.
• Stay under 3,500 RPMs and keep air moving for the next 500 or so miles.
• Avoid WOT
• Avoid long distance steady RPMs.
• Use a good quality 20W50 oil.
• After the first 500 miles or so, let er rip.

Great XLFORUM thread with lots of pics on home made tools. ⁴⁷⁾http://xlforum.net/forums/showthread.php?t=395586&highlight=tap))

Types:

Use:

• Apply (anti-seize compound or Locktite (or equivalent)) as necessary to the bolt threads before installing. Align each bolt chamfer with it's corresponding threaded hole and counter rotate the fastener to the tightening direction a few degrees until you feel the threads “jump”, that indicates the threads are aligned to start in sync. Start all of the fasteners in a component before you tighten any of them…not even hand tight. Any misalignment of the part can side load the last fastener enough to prevent it starting or promote cross threading. ⁴⁸⁾ By hand, all bolts should run in rather easily. If not, there may still be trash/ debris caught up in the threading (which can alter you reaching proper torque values). Turn all bolts in sequence by hand until snugged. Locktite / anti seize may offer drag on the bolt(s) in which case you can use a socket without the wrench to turn the bolts to snug by hand. Do all the bolts the same way around your piece in a cross pattern to ensure evenness throughout. Find the torque specs for your application and divide that number by three. You now have three different torque specs. Use the cross pattern on all bolts with the first (lowest number torque, then around again, all bolts, with the second torque number, then around again, all bolts, with the final torque. Lastly, go back around with the final torque to make sure everything is even. When applying torque, always use slow even motions. Applying torque too fast leads to fooling the torque wrench to click before torque is actually reached (the science above my head). ⁴⁹⁾ Article by Oldrump1 from the XLFORUM http://xlforum.net/forums/showthread.php?t=1959533

• Your favorite brand of brake cleaner can be used to clean a host of bike parts. Just be careful not to get it on rubber and wiring.

• Denatured alcohol or D.O.T. 5 brake fluid. Do not contaminate it with mineral oil or solvents. ⁵⁰⁾

• Something that often comes up on these old bikes, due to age and due to previous owners' shenanigans, you quite often see many good reasons why hand tools and not hand guns should be licensed. ⁵¹⁾
• There are three ways to unlock the bolt: chemical, thermal, and mechanical. You pretty much want to attempt the process of unsticking in that order, too. ⁵²⁾
• The reason the bolt gets 'stuck' (more often than not) is corrosion expands - iron oxide can expand to be something like 17 times as thick as the base steel was. The oxidization (rust) effectively locks the bolt in place. ⁵³⁾

• Chemical attacks are not instantaneous events; Pop would, when working a bolt on his Model A, often squirt the bolt once a day for two weeks, then give it a rap to try to loosen corrosion before walking it out conventionally. Sometimes it works, sometimes it doesn't. ⁵⁴⁾

• Even a good penetrating oil sometimes just needs time. First, follow the label on your choice of oil. A rule of thumb is a 24 hour soak, followed by a few taps with a hammer or rubber mallet to set up some vibration in the threads to distribute oil and friction. This procedure can be duplicated as often as you feel comfortable with and it depends entirely on your time frame allowed. It's not possible to nail down a set day(s) or hour(s) as every situation and climate is different.
• The chemical saturation starts with a good penetrating oil. There are lots of good products for loosening stuck bolts including but not limited to: ⁵⁵⁾

• P'B Blaster
• Kroil
• Liquid Wrench
• Tap Magic works wonders for deep penetration
• WD-40 is not considered a good penetrating oil, but if the bolt can be turned just a pinch (left or right) and back then you can squirt this into the threads on every turn and it may help but your still better off using penetrating oil instead. ⁵⁶⁾

• Heat in this instance is applied to the bolt surroundings but not to the bolt. The idea is to thermally expand the hole that the bolt is in without expanding the bolt itself or weakening it's internal properties. ⁵⁷⁾
• For exhaust nuts/studs etc, or removing exhaust pipes, run the engine and get it real hot, then try. ⁵⁸⁾
• For bolts stuck in aluminum castings, take a propane torch with a wide heating tip, not the narrow soldering tip, or an electric heat gun and heat the aluminum up. Keep the heat source moving. The aluminum expands more than the steel bolt and loosens up the stickiness. A propane torch or heat gun used with movement will not warp alumnium. Just don't heat it more than about 210 degrees, which is when you can spit on it and the spit boils and sizzles. Oxy acetylene torch can melt aluminum so that is a no-no for me. ⁵⁹⁾
• For stuck brake calipers etc, someone one here (XLFORUM) suggested and swears by boiling the caliper in a pot of water. Same effect, the aluminum expands. ⁶⁰⁾

• Impact always works better than steady pressure. Jar the wrench or socket handle with the palm of your hand, rather than just pulling on it steady. ⁶¹⁾
• Take a flat nosed punch or drift and give the stuck bolt a few solid belts with a hammer, straight on. It pushes the bolt into the hole and lets it spring out, sometimes breaking the oxide layer holding it in place. Be careful not to damage the screwdriver slots or hex head in the bolt/screw. Brass drift helps for that. ⁶²⁾
• Impact screw driver is the only thing to use on the gearcase and primary cover screws. You hit it with a hammer and twist it at the same time. A must have for any bike workshop. ⁶³⁾
• Right-angle screw drivers let you get more leverage to, or those screwdriver bits for your socket set. But impact driver works much better. ⁶⁴⁾
• A six-sided hex wrench will grip a rounded off nut better than a 12-point socket or box wrench sometimes. ⁶⁵⁾
• Use the right size wrench or screwdriver bit. Sometime you can put a Crescent wrench on a square shank screwdriver for more leverage. ⁶⁶⁾
• ALWAYS use good quality tools. A Snap On or Craftsman wrench will grip a bolt better than a cheap Chinese wrench. That is why professionals pay the extra money for good tools. Saves them money on repairing damage from cheap tools. ⁶⁷⁾
• An air impact wrench is good for undoing stuff but never use it to tighten. It's too easy to over torque and strip the bolts. ⁶⁸⁾
• Do not use an air impact wrench on the crankshaft mainshaft nuts etc, it can throw the crank assembly out of true, so they say. ⁶⁹⁾
• Carefully weld a piece of metal onto a rounded or broken bolt head so you can grip it and turn it. ⁷⁰⁾
• Go round the other side of the bolt and cut the nut off it using a grinder or hacksaw. ⁷¹⁾
• File two flats on a rounded bolt head so you can get the next size smaller wrench on there. ⁷²⁾
• A half inch breaker bar stuck into an 8 foot long piece of black pipe. It has never meet a nut or bolt it could not take off. I prefer this to the impact gun. ⁷³⁾

• Neat motorcyle Phillips head screw trick: If one is stubborn and wants to 'cam out' (screwdriver lifts out of the slots while attempting to turn the screw) you can sometimes restore the screw enough to get it out by flattening the head slightly with wrong end of a punch - or a machinist's round punch (flat face).
  • The idea is by flattening the head, the mushrooming effect 'closes' the slots, allowing a screwdriver or impact driver to get enough grip to back it out.
  • Be sure to use fresh Phillips tips. Just because it looks like a #3 Phillips head tip doesn't mean it still is one! Go to the store, buy a screwdriver with replaceable tips and a half dozen tips - and THROW OUT a tip when the edges become the least bit rounded. ⁷⁴⁾
• A 1/4 drive ratchet with a 1/4 six point socket will drive most any phillips head replaceable screw point - especially those in tight places. Did the float bowl/idle jet swappie this past morning on the bike without taking the air cleaner off; if I'd used a conventional screwdriver, the angle would have caused the outboard screws to camout. I was able to keep the bit in the screw with one hand - and turn with the other. ⁷⁵⁾
• If you have a Phillips head that is camming out, put a little valve grinding compound on the tip of the screwdriver. It will give the screwdriver tip a lot of extra bite. ⁷⁶⁾
• Quite often, when a bolt or screw won't back out, I'll reverse the impact and give it a go that way. The next reverse impact usually pulls it out. It just wanted to be loosened by tightening ⁷⁷⁾

• That tiny, tiny bleed nipple will shear off real easy. I use a six-sided small box end wrench on it. 12 point just slips to easy.
  • Tap the nipple straight on a few times with a flat punch to jar it loose.
  • If you have the caliper apart, heat the body with heat gun or propane torch to loosen it up.
  • You can also buy a thread repair kit from JP etc that you drill and tap a larger metal fitting into the caliper and the nipple screws into that. ⁷⁸⁾
• If you can get one on it, a deep well six point socket works real good. On small bolts and nipples like bleed nipples, ALWAYS, ALWAYS, ALWAYS open them by hitting the wrench with a small hammer or like tool. Metal to metal tapping, too - not a deadblow plastic mallet. You need that sharp impact to break loose the small bolt or fitting; us gorilla wrenchers can shear a fitting thru constant pressure right quick.
  • You can keep a junk ratchet in the box for just such an occasion. Sure - you can get a little breaker bar - but on delicate, often tight space work, a chinese disposable ratchet comes in handy! ⁷⁹⁾

• As to the brake hose going into the caliper, use only a proper brake hose wrench from the auto parts store. It is a six sided box end wrench with a slot in it so you can fit it over the metal tubing. Then jar the wrench to get the hose unscrewed. If you try to use an open end wrench on that pipe fitting, it will almost guaranteed just round off the flare nut hex. ⁸⁰⁾

So you have wrenched on that stubborn bolt long enough and hard enough that the damn head broke off, leaving the shank of the bolt stuck in the job. ⁸¹⁾

• First step is most important: WALK AWAY. ⁸²⁾
  • The problem is not insurmountable, but it takes patience and a steady hand. ⁸³⁾
  • Do not attempt to deal with it when you are pissed off and or tired. Come back another day and start afresh. ⁸⁴⁾
  • Take a flat nosed drift and hammer and give that end of the broken bolt a few good taps to loosen it up. ⁸⁵⁾
  • See if you can get it out with a screwdriver jammed against the broken end. Sometime you can get lucky and the release of tension when the bolt head comes off releases the bolt. I know this to be a fact but can't remember the last time it was actually that easy. ⁸⁶⁾
  • Take a small center punch and try to tap the bolt end around anticlockwise to see if it will move. If you can get it out a thread or two, vice grips will screw it the rest of the way out. Not often this one works too, but sometimes it does, specially with larger bolts where you can get some leverage on it by digging the punch in near the outer diameter. ⁸⁷⁾
  • Refer to the heat section above
  • If the bolt shank extends out of the hole far enough, a 12'-18” pipe wrench can be used to grab the bolt and remove it. Vise grip pliers always stand the chance of stripping around the bolt shank while reducing the metal around the body.

OK, so the SOB won't shift or budge. Time for some very careful skilled artisanship. You don't want to drill into the threads in the hole. ⁸⁸⁾

• First step is to tape off area around the bolt and cover any parts susceptible to debris and flying metal. ⁸⁹⁾
  • Find or create a flat plane near center of the bolt using a small file or grazing across it with a Dremil tool with a metal cutting blade attached.⁹⁰⁾
  • Use a center punch to make a mark right in the center of the bolt shank. A fat punch with a wide point works better than a narrow pointed punch because you can see the outer edge of the punch lining up with the outside of the bolt on say a 1/4 or 5/16 bolt, the most common bike sizes. ⁹¹⁾
  • Then you have to drill slowly and carefully down the center, getting a buddy to look on from the side and eyeball you are keeping the drill square to the job. ⁹²⁾
  • Use a drill bit plenty smaller than the bolt and then you can open the hole up with progressively larger bits. ⁹³⁾
  • As you drill it out, tension in the bolt is released, loosening the threads. So you might be able to stick the square tang of a file in there and turn the remaining shell out of the threads or you can use a thread extractor or Easy-Out to back out the remaining shank. ⁹⁴⁾
• Stud Extractor and Easy-Out is a small, square tapered or spiral tapered tool kind of like a tap, that you screw, left hand threaded, into the hole, in the bolt and then CAREFULLY use it to screw the drilled bolt shank out. WARNING: Small spiral Ezyout tools don't take much force to break. Then you have a hardened tool steel tip embedded in your job. You cant drill it. It is harder than a drill bit. If you can't get that out, a machine shop will have to use a electro discharge machine to burn it out. Expensive and messy. Be very careful. ⁹⁵⁾
• Use a Snap-On style stud extractor. That is a small round plug with kind of teeth on it. You drill a SPECIFIC sized hole (in the tool instructions) then hammer the tool into the hole and use it to hook up your ratchet handle and screw it out. ⁹⁶⁾
• Left handed drill bits (no, that is not a joke). You can buy them at engineering shops and machine oriented sales companies. Get one just smaller than the root diamter of the bolt - ie, it will fit through a nut that same thread size with just a bit of slack to spare. You run your pistol drill backwards and drill out the bolt or stud as above. As the drill turns in the “undo” direction, it tends to screw the bolt out of the hole as it goes, and the hole relieves tension on the bolt so it loosens up and screws out. ⁹⁷⁾
• If you are working on a small part you can turn over and drill out from the back side, a normal drill bit will have the same effect. It can grab that bolt as it goes and turn it in the undo direction. ⁹⁸⁾
• Ideally of course, setting the job up in a drill press is always better than wobbling around with a pistol drill. But an Ironhead motor or frame is not always that portable. ⁹⁹⁾
• When drilling out a bolt, get the correct replacement in hand first, so you know how deep it is, and you can mark your bit at the same depth. ¹⁰⁰⁾
• Inspect all the threads on bolts and threaded holes to make sure they are clean of all debris, gasket material, rust and oil.
• Chasing threads simply means running a tap/ die back through the threads to insure they are all straight and clean which helps you achieve proper torque values when installing the bolts. Be cautious to match up to the existing threads your working on. If metal starts being cut while running down a tap/ die that's a good sign either your not locked into the threads or that you have some warped or damaged threads.
• Wire wheels on a bench grinder works great for cleaning bolts. ¹⁰¹⁾
• Soaking bolts and fasteners in gas or solvent will help to break loose old gasket material, oil and grime.
• Threads can also be cleaned with an old toothbrush and some solvent or gas or just simply sprayed down with your brand of brake cleaner.

The actual failure mechanism: ¹⁰²⁾

103)

• So when you loosen the plug the upper partially fractured (cast alum don't like flexing) threads will “move back in position” as the plug reengages the 'good' lower threads. ¹⁰⁴⁾
• After a few ins and outs the upper threads let loose from the back and forth flexing. ¹⁰⁵⁾
• Where upon:
  • “My plug stripped on the way out”. or “It just spins, won't get tight, won't come out”. or “I didn't even put the juice to it, it just never got tight”. ¹⁰⁶⁾

• This is where chasing threads is essential. Where torque specs are designed to tighten to a known point that is before the bolt would break and/or before the piece your working on gives or cracks under pressure (also given the composite of the bolts), the practice of proper torque on a bolt/ hole can also stress new threads.
• The individual threads on a bolt or a threaded hole could have been warped due to material composite, heat, initial torque and pressure applied during (previous) normal operation. Warp-age could have been been increased from too much initial torque and/or uneven initial torque all around on the piece that had been installed.
• That said, these bolts and threaded holes were initially threaded (internal or external respectively) with taps and dies. Consequently, taps and dies are used to chase the holes / clean the bolts back to their original shape/ cleanliness and done with plenty of good cutting oil.
  • Roll Form Taps- used to pressure form threads in softer material like aluminum. I have used roll form taps to “restore” damaged threads. They work well because they will actually push the metal back to shape as opposed to cutting it away, word of caution they use a lot of force and are way easier to break so don't get to western with them. Oil and steady pressure. Turn in 2 or 3 turns back off 1 or 2 turns to allow the pressure to come off and if you are using a cut tap the cut material needs to come out. One word of caution, when you buy taps and dies don't be cheap you get what you pay for ¹⁰⁷⁾
• While chasing the bolts / holes you will experience metal shavings coming out of the holes and down the bolts. This is normal and how much depends how much damage has been applied to them. You are in fact re-shaping these to back to their original shape. There really isn't much reason to replace a bolt other than cosmetics or rot unless it cannot be re-threaded or has been overly torque stressed. This is a condition in which, on the way to final torque, the bolt begins to stretch or twist from it's protruding center but not threading any longer into the hole as cylinder head bolts can do. ¹⁰⁸⁾
• There are different methods to tapping / chasing holes depending on the situation.
  • A through hole is what it says, it goes in one side and out the other of the piece you are working on. Don't stop turning the tap until it has gone in far enough to reach past the bottom, given the chamfered end of the tap itself.
  • A blind hole is simply one that does not go through all the way like a 3/4“ thick piece of metal with a 3/8” deep hole in it. Once you run the tap into it, you can't see the bottom , thus it is a blind hole. Chasing a blind hole can be more tedious. As the tap reaches farther in, you aren't quite sure where it will bottom out so you have to use caution when the tap starts turning tighter. Turning past the bottom will always end up cracking your piece or breaking the tap off in the hole. Turn in about a quarter turn, back out a half turn, run it in until it stops or gets resistance, go in about another quarter turn and back out all the way. This helps gather the shavings/ trash into the flutes of the tap and away from the threads- which creates resistance. Clean the tap, blow out the hole of all metal shavings/ trash/ gasket material, then go back in.
• You'll get a feel for it and when it hits bottom, you'll feel that to be harder or more of an end of the journey feeling. All the while your using cutting oil which can gather in the bottom of the hole and or mix with any trash in the hole. Truthfully this is the same procedure for tapping any hole as far as touch and feel. If this is not cleaned out before going back in with the tap, it can hydro lock ¹⁰⁹⁾the end of the tap (pressurize the area between the tap end and the bottom of the hole) which not always but can stress the piece from the pressurized area and cause cracks or holes especially if you are using a flat ended tap with no tapered point on the end. If you see oil seepage coming up from the sides of the tap, STOP, unscrew it, clean the tap and the hole before going any further.
• I will typically send a pin needle or the like down to the bottom of the hole to see if there is any embedded crap at the bottom. ¹¹⁰⁾

• Engineering supply, auto parts and hardware places sell several kinds of insert kits that you fix this with, eg Helicoil, Keensert, Timsert etc.
• A helicoil is a small stainless alloy steel spiral. The inner diameter is the right thread to match the original bolt. The outside diameter has a larger thread and the kit has the right size drill bit included.
  • Carefully drill out the stripped hole with the 'kit supplied' drill bit. Use a try square to make sure you are drilling square to the surface, and get a buddy to eyeball it as you drill.
  • Using the supplied tapping bit in the kit, thread the larger hole you have drilled. Again use an engineer's square to make sure you have it square as it goes in. If you have no engineer's square, use the corner of a book cover or something you know is 90 degrees. Check in two directions, back and forth and side to side. Use appropriate cutting oil or plenty of WD40 if tapping into aluminum.
  • Always turn the tap about half a turn in, then quarter of a turn back out, so the cutting motion is kind of back and forth to clear the swarf chips off the cutting edges.
  • Use a proper tap wrench to turn the tap. Using a Crescent wrench on a tap is a good way to get it crooked or even break it. Even in a tight corner, you can get tap wrenches with a sliding cross bar handle. Although, if really desperate in a tight spot , I have used my 1/4 drive socket set ratchet handle with a socket that fits the tap shank. This should only be done when there is absolutely no alternative. The proper tap wrench will save you much heartache.
  • Make sure the thread is tapped deep enough for the whole insert to fit in the hole. Inserts can be bought in several depths.
  • Then clean the new thread and the insert thoroughly with carb cleaner, rubbing alchohol or Loctite cleaner/primer. I always like to put red Loctite on helicoils so they stay put forever and don't screw out with the bolt. Put the Loctite on the outer diameter threads only, so they lock to the hole.
  • Then screw the insert in with the special tool in the kit. Then break off the tang of the insert, either with the special tool in the kit, a punch and hammer or long nose pliers.
  • Wipe off excess Loctite. Grease up the bolt so it wont stick to the loctite, and screw it in to make sure all is good.
  • Then take it out and let the loctite cure overnight.
  • This repair actually makes a stronger thread than an original aluminium thread. ¹¹¹⁾

• This tool is a cross between a tap, a die and a file.
  • The end part can be used to put down inside a hole and sort of scrape clean the thread of the same pitch as the tool.
  • The side can be used like a file on damaged bolt threads to get them back to form. On a special thread like the end of a crankshaft that has a large diameter fine pitched thread that no standard die will fit. Use a thread file with the same number of teeth per inch. ¹¹²⁾

• The only way I have found to remove the broken tap is to use a small hole punch to the center of the broken tap and smack it with a hammer while exploding the hardened tap. You don't stand a chance at drilling it out without damaging the hole/ threads and chances are since pressure was enough to break the tap, it'll take more pressure than that to remove the broken lil stubby that's left. ^{113) 114)}

• idahopilot: Is it necessary to “chase” the threads to accessories before adding them to your bike?
  • capttawes: No it's not really necessary but sometimes those accessories have a build up of chrome, paint or powder coat that get in the threads making it tight and easy to cross the threads. If you find it necessary or run into a problem where you've stripped/crossed threads on some parts a simple once over with a std. set of tap & dies will do the trick.
  • Folkie: I generally try out a nut on a threaded stud of a part or try out a screw in a threaded hole. You can soon tell if the threads are OK. Sometimes just turning the nut or screw back and forth a few times sorts out any roughness. If not, a pass with a die or tap does the trick. If you've got adjustable dies and you use a die holder (I often don't for this sort of thing, just hold it in my fingers), make sure you haven't tightened the screws in the die holder to make the die smaller than standard size. We want to clear the threads, not recut them. If you haven't got a T handle tap holder in your tap and die set, that can be a useful addition. It's less cumbersome to use for this sort of thing. Just make sure you're using the right size tap or die. A cheap vernier caliper and a screw thread gauge are useful to size threads if you're not sure about them.
  • Another tip for cleaning out the chrome flashing on new parts is to start the tap at the backside of the hole where you have clean threads. This will allow you to start the tap properly and keep you from messing up the angle of the hole. Once started properly with some lube on it it should just screw right through the hole to the front side and clean out the excess chrome in the threads. If it feels like it is harder to thread in than a bolt in clean threads, STOP!! Back out and try again and doublecheck that you have the proper thread pitch on your tap.
  • To check the thread pitch get a thread pitch gauge and check it against the bolt that is supposed to go in the hole. These look like a feeler gauge full of combs and you lay each comb against the threads until you find the one that matches the threads on the bolt that is supposed to go in the hole. Thread gauges are cheap, pick one up and go to ACE Hardware and practice against bolts with a known thread pitch to see how they work. ¹¹⁵⁾

• In lieu of having torque specs at hand, below are general torque specs for different fasteners. However, nothing takes place of manufacturer torque specs for your specific applications. The torque numbers reflect pressures the bolts can take which doesn't take into account the amount of clamp force for the piece(s) you are clamping.
• When using oiled fasteners, you should take into account the added pre-load from the oil before applying advertised torque to avoid shearing off the bolt head or cracking/ breaking the piece your working on. You can use the Wet Chart below to calculate a torque value with the added pre-load.

• Convert ft/lb to N*m by multiplying by 1.3558 ¹¹⁶⁾
• Fastener strength of SAE bolts can be determined by the bolt head grade markings. Unmarked bolt heads are usually mild steel. More grade markings indicate higher strength fasteners. For instance, grade 5 may have three hash marks from the center out to the edge, grade 7 may have five hash marks and grade 8 should have 6 hash marks.¹¹⁷⁾
• These are only generalized specs, see your FSM or instruction manual for specific torque values per application.

If bolt threads are lubricated with light oil or anti-seize compound, the torque required to achieve the proper bolt tension is reduced. Below are charts with the proper “wet” torque values for type of bolt used: All charts property of and used by permission from Allied Systems Company.

• Displacement: pi x (radius squared) x height (example: 4 inch bore, 4 inch stroke) = 3.14159 x (2 squared) x 4 = 50.265ci of displacement per cylinder
• Cubic Centimeters to Cubic Inches: cc ÷ (2.54 cubed) (example: 1200cc) = 1200 ÷ (2.54 cubed) = 73.23ci
• Cubic Inches to Cubic Centimeters: ci x (2.54 cubed) (example: 100ci) = 100 x (2.54 cubed) = 1638.7cc
• Horsepower: (torque x rpm) ÷ 5252 (example: 80 ft-lbs at 4000 rpm) = (80 x 4000) ÷ 5252 = 60.93hp
• Torque: (horsepower x 5252) / rpm (example: 100hp at 4000 rpm) = (100 x 5252) ÷ 4000 = 80 x 4000) / 5252 = 131 ft-lbs.

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