EVO: Oiling & Lubrication

Engine Oil Routes

Right Crankcase Feed Galley

86-90 engines

The lifter oil feed galley is a hole located along the top of the case between both intake tappets.

  • The feed galley is responsible for carrying oil to the lifters.
  • It gets it's oil from the cam cover.
    • A hole is internally routed from the top to the bottom of the cover with a hole exiting in a corresponding hole in the case.
    • The cam cover gets it's oil from the oil pump via intersecting holes between the bottom of the case and the cover.
    • Feed oil is routed inside the cover but not to the gearcase.
  • The hole in the middle of the case at the top intersects into the internal oil feed galley.
  • Cross drilled passages intersect the main feed galley and carry oil to each intake lifter.
    Exhaust lifters are fed oil (bore to bore) from a drilled passage into each one's respective intake lifter bore.
  • This is the end point of static oil pump pressure to the top end.
    • The lifters supply oil pressure to the rocker boxes.
86-90 main oil feed path 1)

91 and up engines

The main oil feed galley is a horizontal passage located along the top of the case beside the tappet blocks and lifters.
It runs from the filter pad to the last lifter bore (lifter for #1 cam).
This oil galley feeds the lifters, cam cover / pinion shaft / hole in pinion gear to the rod bearings and also the gears on cam #2.

  • The feed galley is responsible for carrying oil into the engine.
  • It gets it's oil from the filter / check ball.
  • 91-99 engine feed galley is an internally drilled hole in the case.
    • It runs behind and into on both sides of the small cavity (small slot) milled into the outside edge of the case.
  • 2000 and up engine feed galley is an external slot milled into the outside edge of the case.
    • The oil passage runs on the outside (right) of the lifter bores as in 91-99 cases with a hole drilled through it into each lifter bore.
  • Cross drilled passages intersect the main feed galley and carry oil to each lifter from the feed galley.
    • This is the end point of static oil pump pressure to the top end.
    • The lifters supply oil pressure to the rocker boxes.
  • A small amount of oil sprays down onto the rear intake (#2) cam gear through a tiny hole in the middle of the feed galley.
  • The cam cover gets it's oil from an intersecting passage in the feed galley at the top of the cover.
    (the gearcase gets no oil from this passage in the cover, outside of spill from the pinion shaft bushing)

In examining the area directly behind the filter inside the gearcase;
You can see the oil path (channels from the filter to the engine).
There is a plug on the outside case in the area of the filter.
The plugged hole is from where the MoCo drilled the oil passage to connect the outlet of the oil filter to the lifters. 2)
After they drill it, they stick a plug in it.
There are other plugged holes like that on your motor where the drilling operation left a hole that had to be plugged.

On 91-99 engines, the oil feed galley is internal from
the filter pad. Oil travels to each lifter individually
from this cavity. 3)
Rifling hole for the feed galley is plugged outside
the case near the filter. 4)
On 2000 and up engines, the oil feed galley is
external. Oil travels to each lifter individually from
this cavity. 5)
The rifling hole for the feed galley is plugged outside
the case near the filter. 6)

Top End Oiling

Lifter oiling

All

  • Lifters are fed oil from the oil galley in the upper part of the right case half.
  • Each lifter acts like a pump sending pressurized oil up through the center of the pushrods. 7)
  • As the camshaft lobe travels through its apex, the load is reduced on the lifter piston, 8)
    And the internal spring returns the piston to its neutral state so the lifter can refill with oil.
    This small range of travel in the lifter's piston is enough to allow the elimination of the constant lash adjustment.
  • Oil under constant pressure is supplied to the lifter via an oil channel, through a small hole in the lifter body. 9)
    When the engine valve is closed (lifter in a neutral position), the lifter is free to fill with oil.
    As the camshaft lobe enters the lift phase of its travel, it compresses the lifter piston, and a valve shuts the lifter's oil inlet.
    Oil is nearly incompressible, so this greater pressure renders the lifter effectively solid during the lift phase.
  • It's the check valve in the lifter that seals the cavity underneath it when the cam tries to push the lifter up. 10)
    The increased pressure in that cavity forces the ball or disc (depending on the lifter design) against the seat.
    The oil feed path is however made smaller because the path gets restricted, as the oil feed hole is high up on the lifter body.

This (slow) animation shows it well. Notice the green area on the left:
11)

There are, however, hydraulic lifter designs that completely cut off the oil feed when you come off the base circle.
For example:
12)

86-90 engines:
The oil feed to the lifters comes from the oil pump, through a passage in the cam cover to the feed galley in the top of the right case.
The intake lifters are fed oil from the feed galley hole.
Each exhaust lifter is fed from it's corresponding intake lifter bore.

86-90 lifter oiling path 13)

91-99 engines:
The oiling hole for the lifters in 91-99 engines is drilled from the inside of the right case out through the lifter bore and into the case oil galley.
All four lifter bores are capped on the inside of the right case.
This left a blind hole between each lifter toward the inside of the case.

91-99 Lifter oil path from filter. 14) Capped holes for the lifter bores inside the case. 15)
91-99 lifter bore 16)
A look inside the oiling holes in the lifter bore on a 91-99 case. Notice the capped hole toward the case in the third pic. 17)

2000 and Up engines:
However, the oil galley was now cut into the right case instead of a rifle drilled hole.
This made it easy to drill oiling holes to the lifters from the outside of the case into the lifter bore.
So there were no lifter oiling holes to cap on the inside of 2000 and up cases.

2000 and Up engine lifter oil path. 18)Inside of case has no capped holes for lifter holes. 19)

Rocker arm / Valve oiling

All

  • Oil flows up the holes in the pushrods from the lifters and enters the rocker arms through a hole in the pushrod end of the arm.
  • Oil is supplied to the valve stems and springs from the drilled holes in the underside of each rocker arm above them.
    • The holes are only on the valve side of the rocker arm.
  • Oil is also forced through the clearance between the rocker arm shafts and bushings for lubrication there.
Rocker arm oiling path 20)Valve oiler holes 21)

Rocker Box Oiling

91-99 engines

  • Crankcase pressure (air and oil mist) is routed up the pushrod tubes (bypassing the falling oil from the rocker boxes) into the rocker box.
  • Collected air pressure and oil mist in each rocker box is routed up into a sealed cavity in the lower portion of the box.
  • This mixture passes up from underneath a rubber one-way valve (umbrella valve) sitting over the cavity inlet.
  • The oil is designed to separate from the air by;
    • Hitting the underside of the umbrella valve and falling back into the sealed cavity in the middle rocker box.
    • From there it should drain back into the lower rocker box through a tiny hole behind the umbrella valve.
    • This tiny hole is in a recessed area behind the umbrella valve.
    • There is a certain amount of backpressure in the sealed cavity away from the air exit hole.
    • This backpressure should help push the oil into the tiny hole and back into the lower rocker box area to be carried back down to the lower end.
  • Air pressure is designed to continue up past the umbrella valve and exit a hole in each head on the intake valve side.
  • Pressure escapes the head through the hollow bolts (one in each head) that hold the air cleaner mount.

2000 and Up engines

Bottom End Oiling

Pinion shaft and bushing

All

  • Pressurized oil in the pinion bushing is sent through a hole in the (hollow) pinion shaft toward the crankshaft area.
    • Oil travels to the right flywheel and routes through the crankpin, out the oil hole in the middle of the pin and to the rod bearings.
  • This is the end point of static oil pump pressure to the bottom end.
  • Oil leaving the rod bearings flows into the crankcase to be scavenged by the oil pump (or splashed into the gearcase).
  • Crankcase pressure moves the oil from this point.

Cam Oiling

  • Oil flows off the pushrod side of the rocker boxes through the pushrod covers, into vertical holes in the lifter bores and into the gearcase.
    • Oil falls on the cam lobes on the way down this hole.
    • Some of this oil is transferred between the gear teeth.
  • The rear intake (#2) cam gets a little oil spray from the right case oil feed galley through the small orifice underneath the open cavity in the case.
    • That oil is transferred between the teeth of the cams.
  • Oil flung off the cams lands in the gearcase to be collected into the scavenge (return) side of the oil pump.

Below are pics of the restricted orifice underneath the oil feed galley in the case that shoots a small stream onto #2 cam.
#2 cam rotates counterclockwise and the oil is sprayed on the right side of the cam gear for extra cooling.

(L) 91-99 22), (R) 2000 Up 23) cam oiling hole from the feed galley

Cam Cover Bushings

All cam bushings are fed from splash oil into channeled holes drilled behind the bushing faces.
#1, #3 and #4 cam bores have channels drilled from the top down into the back side of the bores.
The channel for #2 cam bore starts at the bottom and is drilled into the back side of the bore.
The pinion bushing (as well as the hole in the pinion shaft) is fed from a cross drilled hole in the top of the cover.

Cam Cover \ Gasket

91 and up Sportster engines have an internal rifling hole drilled into the lower left side of the case running past the left side of the oil pump.
That extra hole (in the picture below) is benign and doesn't need a hole in the gasket to match.
That hole is purely an artifact of how they connected two passages for routing crankcase oil up to the oil pump's scavenge section.
They drill that hole to connect the two passages, and then it gets blocked off naturally by the cam box cover and gasket. 24)

Also, in 2000, the factory changed the oil routing to the lifters to make manufacturing the cases easier.
The newer cam cover on the left in the pic below and has two extra grooves along the top.
These grooves let oil get to the lifters.
If you have an older style gasket, it will not have cutouts for the grooves and you won't get oil to the lifters.

Rubbermount Evo vs Rigid Evo Cam Cover Internals 25)
Both have been chopped on the outside but the gearcase perimeter is intact on them for reference.
91-99 cam cover gasket 26) 91-99 cam cover seals off the extra hole. 27)
2000-up cam cover gasket 28) 2000 up gasket seals off the extra hole. 29)

Case Oiling and Drainage

86-90 Engines

Gravity

  • Gravity oil (drained from rocker boxes and head/cylinder drainage) falls on moving parts and into the crankcase.
    • Oil collected in the rocker box is returned to the crankcase through a passage in the cylinder and the head.
    • Oil collected in the push rod areas of the heads / rockers flows down the pushrod covers.
      • Then it flows down into the gearcase / cam chest through vertical drain holes in the tappet blocks.
      • Collected oil in the gearcase is routed to the crankshaft sump area via a low hole in the wall between them on the right side of the pinion shaft.
    • Excess oil mist drawn into the gearcase breather is separated from crankcase air pressure at the gearcase breather valve.
      • The separated oil (and condensed oil in the exit hose) flows into a drain hole below the breather valve and back into the gearcase.

Splash

  • Occasional excess pressured oil (from the oil filter pad) is dumped into the gearcase by the oil pressure relief valve.
    • High pressure oil, when cold (on startup), opens the pressure regulator.
    • The excess oil is dumped into the gearcase and routed to the sump area via the low hole in the wall between the gearcase and the crankcase.
  • Splash oil in the sump area of the crankcase serves to lubricate the moving parts as well.
  • Splash oil (from the up and down movement of the connecting rods, crankshaft and pressure generated under the pistons on downstroke) serves to lubricate;
  • Cylinder walls
  • Pistons, piston pins
  • Cam gears and bushings
  • Main bearings
86-90 engine sump splash holes 30)

Oil Pump Scavenge

  • Drainage
86-90 oil scavenging 31) 86-90 cam cover 32) 86-90 Oil Pump Oiling Paths. 33)

91-Up Engines

Gravity

  • Gravity oil (drained from rocker boxes and head/cylinder drainage) falls on moving parts and into the crankcase.
    • (91 only) - Occasional excess pressured oil (from the oil filter pad) is dumped into the gearcase by the oil pressure relief valve.
      • 91 engines kept the oil pressure relief valve that opens at 30-35 psi and dumps oil into the gearcase.
      • The pressure relief was removed from future models.
    • 91-03
      • Oil collected in the rocker box is returned to the crankcase through a passage in each head and cylinder.
      • Oil collected in the push rod areas of the heads / rockers flows down the pushrod covers.
        • Then it flows down into the gearcase / cam chest through vertical drain holes in the tappet blocks.
      • Excess oil mist splashed into the rocker boxes is separated from crankcase air pressure at the breather baffles (plain umbrella valves).
        • The separated oil flows into drain holes in the rocker boxes and back into the crankcase.
Rocker box drainage 34)
91-03 breather holes in the rocker box sections and head 35)
91-03 style front head drainage hole 36) Head drains in the cylinders 37)
91-03 style rear head drainage hole 38) Head drains at the cylinder base on the case. 39)
  • 04-Up
    • Oil collected in the rocker box is returned to the gearcase through a passage in the head and the right case.
    • Oil collected in the push rod areas of the heads / rockers flows down the pushrod covers.
      • Then it flows down into the gearcase / cam chest through vertical drain holes in the tappet blocks.
    • Excess oil mist splashed into the rocker boxes is separated from crankcase air pressure at the breather baffles (fancy umbrella valves).
      • The separated oil flows into drain holes in the rocker boxes and back into the gearcase.
Head drains in the cylinders 40)
1 hole is plugged on each cylinder during installation.
Head drains at the cylinder base on the case 41)
Milled slots in the left case match milled slots in the
right case for oil transfer. 42)
Lower part of slots in the right case exit thru drilled
holes into the gearcase. 43)

Splash

  • Splash oil
    (from the up and down movement of the connecting rods, crankshaft and pressure generated under the pistons on downstroke)
  • Crankcase pressure mixed with oil in the sump area serves to splash (and lubricate) the moving parts such as;
    • Cylinder walls
    • Pistons, piston pins
    • Cam gears and bushings
    • Main bearings
  • Crankcase pressure also serves to help 'push' oil from the sump into the scavenger port of the oil pump.

91-99

91-99 crankcase splash holes. 44) Close up view of a 98 cam chest. 45)

00-03

00-03 crankcase splash holes. 46) Close up view of an 02 cam chest. 47)

04-Up

  • The rubbermounts received an addition in the splash ports.
  • Oil jets were installed on the ports to direct crankcase pressurized oil up to the bottom of the pistons.
  • This is not a redirection of crankcase pressure.
    It's more of a dual spray for a controlled direction upward to the pistons and out the ports in the wall for pressure venting.
04-up piston jets. 48) Piston jets from inside the case. 49)

Oil Pump Scavenge

See also the Evo Oil Pump section of the Sportsterpedia.

  • Drainage
    • Oil collected in the crankcase sump is passage-routed to the scavenger side of the oil pump.
      (by pressure generated by the downward stroke of the pistons and the scavenging effect of the pump)
      Sump oil is collected by the pump at the 'ladle, half spoon, duck bill' protruding from the back of it where oil drops onto the scavenge gerotors.. 50)
    • Oil collected in the gearcase / cam chest is routed to a drain port in the top of the oil pump where it drops down onto the scavenge gerotors.
    • Return oil fills a cavity above the pump's return gears from these dual inlets and pumps the oil back into the oil tank.
  • Below is the case drain for a 98 engine. 51)
    • It's also a rifling hole drilled to connect the sump drain to the oil pump scavenge galley.
    • It could be plugged with a treaded pipe plug or a freeze plug.
Case drain / rifling hole for sump drain 52) Rifling hole is on the back side of hole on the right. 53)
04 and up oil scavenge path 54) 04_up sump drain plug. 55)
98 and Up Oil Pump Oiling Paths 56)


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photos by Mini_blitz of the XLFORUM, labeled by Hippysmack http://xlforum.net/forums/showthread.php?t=1974615&page=3
4) , 20) , 21) , 26) , 33) , 34) , 37)
photo by Hippysmack
5)
drummerboy4as of the XLFORUM, labeled by Hippysmack http://xlforum.net/forums/showthread.php?threadid=175003
11) , 12)
Lifter animation by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1933342&page=3
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photo by ehrgeiz of the XLFORUM labeled by Hippysmack http://xlforum.net/forums/showthread.php?t=654598&page=2
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photo by WestJC7745 of the XLFORUM http://xlforum.net/forums/showthread.php?t=1971672
16) , 17) , 27) , 35) , 36) , 38)
photos by Hippysmack
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photo by Scuba10jdl of the XLFORUM http://xlforum.net/forums/showthread.php?t=1959021
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photo by Hippysmack of the XLFORUM
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photo by Moved On of the XLFORUM http://xlforum.net/forums/showthread.php?t=87313
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photo by bsaman of the XLFORUM, labeled by Hippysmack http://xlforum.net/forums/showthread.php?t=691283&page=3
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photo by meherdad_it of the XLFORUM, labeled by Hippysmack http://xlforum.net/forums/showthread.php?threadid=944843
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photo by meherdad_it of the XLFORUM, cropped & labeled by Hippysmack http://xlforum.net/forums/showthread.php?t=944843&page=2
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