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techtalk:ref:svcproc26 [2020/03/04 04:55] hippysmack [Machined Squish Band] |
techtalk:ref:svcproc26 [2024/01/22 21:42] (current) hippysmack |
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The squish (AKA "quench") band refers to the area or areas, \\ where the piston comes very close to the cylinder head while passing through top dead center (TDC). ((http://www.hammerperf.com/ttcheckingsquish.shtml)) \\ | The squish (AKA "quench") band refers to the area or areas, \\ where the piston comes very close to the cylinder head while passing through top dead center (TDC). ((http://www.hammerperf.com/ttcheckingsquish.shtml)) \\ | ||
- | {{:techtalk:ref:svcproc:squish_band_3_by_aswracing.jpg?direct&400|}} ((drawing by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1720575)) {{:techtalk:ref:svcproc:squish_band_by_aswracing.gif?direct&250|}} ((drawing by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=715370)) \\ | + | {{:techtalk:ref:svcproc:squish_band_3_by_aswracing.jpg?direct&400|}} ((drawing by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160330-squish-band-clearance?t=1720575)) {{:techtalk:ref:svcproc:squish_band_by_aswracing.gif?direct&250|}} ((drawing by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/89229-conversion-using-used-parts-where-to-go-from-here?t=715370)) \\ |
Even though the fire has already been lit, these areas still contain unburned air/fuel mix as the piston arrives. \\ | Even though the fire has already been lit, these areas still contain unburned air/fuel mix as the piston arrives. \\ | ||
The piston sandwiches the air/fuel up next to the head, causing it to "squish", and shoot out toward the flame front. \\ | The piston sandwiches the air/fuel up next to the head, causing it to "squish", and shoot out toward the flame front. \\ | ||
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====== Measuring the Squish Band ====== | ====== Measuring the Squish Band ====== | ||
===== Indirect Method ===== | ===== Indirect Method ===== | ||
- | |||
You can use a piston height gauge to measure how far above or below the cylinder deck the piston is sitting at TDC. \\ | You can use a piston height gauge to measure how far above or below the cylinder deck the piston is sitting at TDC. \\ | ||
Then add that measurement to the gasket thickness. \\ | Then add that measurement to the gasket thickness. \\ | ||
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{{:techtalk:ref:svcproc:1200-1250_squish_band_measurement_by_hippysmack.jpg?direct&400|}} ((drawing by Hippysmack)) | {{:techtalk:ref:svcproc:1200-1250_squish_band_measurement_by_hippysmack.jpg?direct&400|}} ((drawing by Hippysmack)) | ||
+ | |||
===== Direct Method ===== | ===== Direct Method ===== | ||
- | |||
You'll be placing some soft material, such as .065" solder, onto the squish band area of the piston. \\ | You'll be placing some soft material, such as .065" solder, onto the squish band area of the piston. \\ | ||
(clay has been used for this also but it's not as accurate as using solder which won't change thickness) \\ | (clay has been used for this also but it's not as accurate as using solder which won't change thickness) \\ | ||
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* Write the measurements down to conclude and average the squish band dimension. | * Write the measurements down to conclude and average the squish band dimension. | ||
- | | Solder held with grease. ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1720575)) | Remove the heads to reveal how far the solder was compressed. ((photos by JohnK of the XLFORUM http://xlforum.net/forums/showthread.php?p=3944070)) || | + | | Solder held with grease. ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160330-squish-band-clearance?t=1720575)) | Remove the heads to reveal how far the solder was compressed. ((photos by JohnK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-motor-top-end/132786-fixing-a-leaky-top-end-with-pics/page6#post2887799)) || |
|{{:techtalk:ref:svcproc:squish_band_1_by_aswracing.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_1_by_johnk.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_2_by_johnk.jpg?direct&300|}}| | |{{:techtalk:ref:svcproc:squish_band_1_by_aswracing.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_1_by_johnk.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_2_by_johnk.jpg?direct&300|}}| | ||
- | | Measure the compressed side of the solder pieces. ((photo by JohnK of the XLFORUM http://xlforum.net/forums/showthread.php?p=3944070)) | Write the measurements down to conclude and average squish band dim. ((photos by JohnK of the XLFORUM http://xlforum.net/forums/showthread.php?p=3944070)) || | + | | Measure the compressed side of the solder pieces. ((photo by JohnK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-motor-top-end/132786-fixing-a-leaky-top-end-with-pics/page6#post2887799)) | Write the measurements down to conclude and average squish band dim. ((photos by JohnK of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-motor-top-end/132786-fixing-a-leaky-top-end-with-pics/page6#post2887799)) || |
|{{:techtalk:ref:svcproc:checking_squish_3_by_johnk.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_5_by_johnk.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_4_by_johnk.jpg?direct&300|}}| | |{{:techtalk:ref:svcproc:checking_squish_3_by_johnk.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_5_by_johnk.jpg?direct&300|}}|{{:techtalk:ref:svcproc:checking_squish_4_by_johnk.jpg?direct&300|}}| | ||
+ | |||
====== Gaining a Squish Band Due to a Conversion ====== | ====== Gaining a Squish Band Due to a Conversion ====== | ||
**Converting an 883**: \\ | **Converting an 883**: \\ | ||
- | An 883 head has a hemi chamber with no squish band but it's chamber is only 3" in diameter to match the 3" bore size of the 883. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1802811&page=3)) \\ | + | An 883 head has a hemi chamber with no squish band but it's chamber is only 3" in diameter to match the 3" bore size of the 883. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/167919-883-to-1200-1250-conversion/page3?t=1802811&page=3)) \\ |
What's fundamentally wrong with the hemi design is that it gives very poor chamber turbulence. \\ | What's fundamentally wrong with the hemi design is that it gives very poor chamber turbulence. \\ | ||
Poor chamber turbulence means poor air/fuel mixing, resulting in pockets of fuel. \\ | Poor chamber turbulence means poor air/fuel mixing, resulting in pockets of fuel. \\ | ||
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This is because you're now putting a 3-1/2" (1200) or 3-9/16" (1250) diameter piston under that hemi chamber. \\ | This is because you're now putting a 3-1/2" (1200) or 3-9/16" (1250) diameter piston under that hemi chamber. \\ | ||
- | | 883 head on 883 cylinder (no squish). ((drawing by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1802811&page=3)) | 883 head on 1200 or higher cylinder (squish gained) \\ Also 1200 head on 1250 or higher cylinder w flat top pistons ((drawing by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1720575)) | | + | | 883 head on 883 cylinder (no squish). ((drawing by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/167919-883-to-1200-1250-conversion/page3?t=1802811&page=3)) | 883 head on 1200 or higher cylinder (squish gained) \\ Also 1200 head on 1250 or higher cylinder w flat top pistons ((drawing by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160330-squish-band-clearance?t=1720575)) | |
|{{:techtalk:ref:svcproc:squish_band_5_by_aswracing.jpg?direct&300|}}| {{:techtalk:ref:svcproc:squish_band_3_by_aswracing.jpg?direct&300|}}| | |{{:techtalk:ref:svcproc:squish_band_5_by_aswracing.jpg?direct&300|}}| {{:techtalk:ref:svcproc:squish_band_3_by_aswracing.jpg?direct&300|}}| | ||
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**Converting a 1200**: \\ | **Converting a 1200**: \\ | ||
- | |||
====== Machined Squish Band ====== | ====== Machined Squish Band ====== | ||
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Check with your engine builder / supplier for further assistance if you're looking for a complete performance package. \\ | Check with your engine builder / supplier for further assistance if you're looking for a complete performance package. \\ | ||
- | | Piston and head with matched squish band. ((drawing by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1802811&page=3)) | | + | | Piston and head with matched squish band. ((drawing by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/167919-883-to-1200-1250-conversion/page3?t=1802811&page=3)) | |
|{{:techtalk:ref:svcproc:squish_band_9_by_aswracing.jpg?direct&300|}}| | |{{:techtalk:ref:svcproc:squish_band_9_by_aswracing.jpg?direct&300|}}| | ||
====== Reverse Dome ====== | ====== Reverse Dome ====== | ||
- | |||
A piston with a reverse dome has a dish in the middle of it. \\ | A piston with a reverse dome has a dish in the middle of it. \\ | ||
That dish is needed because when doing a conversion, you've got a chamber that's sized for an 883 and a piston that's sized for a 1200 or 1250. \\ | That dish is needed because when doing a conversion, you've got a chamber that's sized for an 883 and a piston that's sized for a 1200 or 1250. \\ | ||
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By dishing the middle of the piston deeply as shown below, the CR can be used on street bikes. \\ | By dishing the middle of the piston deeply as shown below, the CR can be used on street bikes. \\ | ||
- | | Reverse dome piston. ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1802811&page=3)) | 30° Reverse dome piston. ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1802811&page=3)) | Heads machined to match the pistons. ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1802811&page=3)) | | + | | Reverse dome piston. ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/167919-883-to-1200-1250-conversion/page3?t=1802811&page=3)) | 30° Reverse dome piston. ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/167919-883-to-1200-1250-conversion/page3?t=1802811&page=3)) | Heads machined to match the pistons. ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/167919-883-to-1200-1250-conversion/page3?t=1802811&page=3)) | |
|{{:techtalk:ref:svcproc:squish_band_6_by_aswracing.jpg?direct&300|}}| {{:techtalk:ref:svcproc:squish_band_7_by_aswracing.jpg?direct&300|}}|{{:techtalk:ref:svcproc:squish_band_8_by_aswracing.jpg?direct&300|}}| | |{{:techtalk:ref:svcproc:squish_band_6_by_aswracing.jpg?direct&300|}}| {{:techtalk:ref:svcproc:squish_band_7_by_aswracing.jpg?direct&300|}}|{{:techtalk:ref:svcproc:squish_band_8_by_aswracing.jpg?direct&300|}}| | ||
====== Lightning Heads ====== | ====== Lightning Heads ====== | ||
- | + | 1200S heads and the older (pre-rubber mount) SE heads, 96-98 Buell S1 heads, 97 Buell S3 heads, 97-98 Buell M2 heads and Buell Blast heads are the same. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/89229-conversion-using-used-parts-where-to-go-from-here?t=715370)) \\ | |
- | 1200S heads and the older (pre-rubber mount) SE heads, 96-98 Buell S1 heads, 97 Buell S3 heads, 97-98 Buell M2 heads and Buell Blast heads are the same. \\ | + | |
These are what we call "Lightning" heads. \\ | These are what we call "Lightning" heads. \\ | ||
- | 62cc chamber with a 10° squish shelf, 1.715/1.480 valve sizes, the old low floor, squared off bowl ports like all the hemi heads etc. \\ | + | 62cc chamber with a 10° cast in squish shelf, 1.715/1.480 valve sizes, the old low floor, squared off bowl ports like all the hemi heads etc. \\ |
All 1200S motors came with flat tops just like every other Evolution Sportster. \\ | All 1200S motors came with flat tops just like every other Evolution Sportster. \\ | ||
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The problem with those heads was the way in which they added the material. When you just add material to a chamber like that, you shroud the valves. \\ Looking at the chambers, you see a whole lot of material around the valves. That obstructs low lift flow. \\ | The problem with those heads was the way in which they added the material. When you just add material to a chamber like that, you shroud the valves. \\ Looking at the chambers, you see a whole lot of material around the valves. That obstructs low lift flow. \\ | ||
- | ====== Compression Ratio ====== | ||
+ | ====== Thunderstorm Heads ====== | ||
+ | Two years after the Lightning head, HD came out with the Thunderstorm head. \\ | ||
+ | In the Thunderstorm, they went back to 67cc , allowing them to unshroud the valves and a 15° cast in squish shelf. \\ | ||
+ | They paired it with a domed piston to get the compression up to 10:1. \\ | ||
+ | They also improved the ports and went to larger valve sizes (1.810" / 1.575"). This setup is head and shoulders better than the Lightning setup. \\ | ||
+ | |||
+ | The angled squish bands direct the fuel being squeezed out of the squish bands more directly at the flame front. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/1572-questions-about-buell-upgrade?t=2206)) \\ | ||
+ | But the way it's done in the Thunderstorm, it's really rough. Since it's cast in, it's uneven. \\ | ||
+ | Typically from the factory the clearance is .050" or more, and that makes the squish band largely ineffective anyway. \\ | ||
+ | |||
+ | Thunderstorm heads are obsolete now. \\ | ||
+ | They could be machined nice and even, but there's a huge overhang around the perimeter. \\ | ||
+ | So to machine it, typically .035"-.045" had to be taken off the deck, sometimes more. \\ | ||
+ | |||
+ | Below is an example of before and after machining. This is much better with a nice even and consistent squish clearance. \\ | ||
+ | But cutting the deck this much has some side effects, like less valve to piston clearance. \\ | ||
+ | As well as potentially forcing the customer into short or adjustable pushrods. \\ | ||
+ | It also typically makes the chamber too small, forcing us to open it up in other areas. \\ | ||
+ | |||
+ | Also notice how there's not a whole lot of surface area. This squish band is effective up to about a .125" tall dome. \\ | ||
+ | Anything higher than that and the dome goes past the squish band. \\ | ||
+ | |||
+ | | Stock Thunderstorm Heads ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/1572-questions-about-buell-upgrade?t=2206)) | Thunderstorms as Machined ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/1572-questions-about-buell-upgrade?t=2206)) | | ||
+ | |{{:techtalk:ref:svcproc:thunderstom_chamber_by_aswracing.jpg?direct&300|}}|{{:techtalk:ref:svcproc:thunderstorm_as_machined_by_aswracing.jpg?direct&300|}}| | ||
+ | |||
+ | ====== Buell XB/04XL Heads ====== | ||
+ | As delivered, they have flat squish bands with a 62cc chamber. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/1572-questions-about-buell-upgrade?t=2206)) \\ | ||
+ | This lets you toss them on over flat tops and have a squish band with lots of area and 10:1 compression. Not a bad way to do it. \\ | ||
+ | If you want to angle it, it's not a problem, you've got lots of material to work with. \\ | ||
+ | You can make the squish band as big or small as you want. \\ | ||
+ | You can make it match the piston you're using exactly, do relief cuts with the rest of the material to help overlap flow if you want. \\ | ||
+ | You can do all this without excessive deck milling and all the problems that come with it. \\ | ||
+ | |||
+ | The stock valves are the same sizes as the Thunderstorms, 1.810" intake and 1.575" exhaust. \\ | ||
+ | The springs and guides can support up to .550" lift safely, though, versus .500" for the Thunderstorms. \\ | ||
+ | The ports are actually a little better than the Thunderstorms. \\ | ||
+ | The Thunderstorms were a major step forward from the Lightning/Screaming Eagle heads, but the XB/04 XL1200 heads are even better. \\ | ||
+ | |||
+ | | Stock Buell XB Heads ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/1572-questions-about-buell-upgrade?t=2206)) | Machined XB Heads ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/1572-questions-about-buell-upgrade?t=2206)) | | ||
+ | |{{:techtalk:ref:svcproc:buell_xb_heads_by_aswracing.jpg?direct&300|}}|{{:techtalk:ref:svcproc:buell_xb_heads_as_machined_by_aswracing.jpg?direct&300|}}| | ||
+ | |||
+ | ====== Compression Ratio ====== | ||
Since the beginning of the Sportster line, Harley Davidson has changed head gaskets as way of changing or adjusting compression ratio. \\ | Since the beginning of the Sportster line, Harley Davidson has changed head gaskets as way of changing or adjusting compression ratio. \\ | ||
Some were lowered for gas mileage / EPA or raised for performance. \\ | Some were lowered for gas mileage / EPA or raised for performance. \\ | ||
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Then you can fine tune with gasket thickness. \\ | Then you can fine tune with gasket thickness. \\ | ||
However; \\ | However; \\ | ||
- | <blockquote>Three tenths of a point in compression isn't really worth your time to tear it down. What's more, just the tolerance is greater than that. ((aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1230012)) \\ | + | <blockquote>Three tenths of a point in compression isn't really worth your time to tear it down. What's more, just the tolerance is greater than that. ((aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-motor-top-end/123881-bumping-stock-compression-to-10-0-1?t=1230012)) \\ |
In other words it's entirely possible your motor is already 10:1 or higher and likewise it's possible it's already 9.4:1 or lower. \\ | In other words it's entirely possible your motor is already 10:1 or higher and likewise it's possible it's already 9.4:1 or lower. \\ | ||
There's variation in every one of the dimensions and volumes that determines compression ratio. \\ | There's variation in every one of the dimensions and volumes that determines compression ratio. \\ | ||
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====== Effects of Deck Height ====== | ====== Effects of Deck Height ====== | ||
- | |||
In general, deck height has nothing to do with the squish band. \\ | In general, deck height has nothing to do with the squish band. \\ | ||
In the example below with a 3-9/16" bore and the chamber is about 3" in diameter. \\ | In the example below with a 3-9/16" bore and the chamber is about 3" in diameter. \\ | ||
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(or use a thinner base gasket which accomplishes the same thing) \\ | (or use a thinner base gasket which accomplishes the same thing) \\ | ||
- | {{:techtalk:ref:svcproc:stock_883_chamber_by_aswracing.jpg?direct&300|}} ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1720575)) {{:techtalk:ref:svcproc:bathtub_squish_by_aswracing.jpg?direct&400|}} ((drawing by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1720575)) \\ | + | {{:techtalk:ref:svcproc:stock_883_chamber_by_aswracing.jpg?direct&300|}} ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160330-squish-band-clearance?t=1720575)) {{:techtalk:ref:svcproc:bathtub_squish_by_aswracing.jpg?direct&400|}} ((drawing by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160330-squish-band-clearance?t=1720575)) \\ |
\\ | \\ | ||
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So there are situations where decking does change the squish clearance and situations where it doesn't. \\ | So there are situations where decking does change the squish clearance and situations where it doesn't. \\ | ||
- | {{:techtalk:ref:svcproc:stock_thunderstorm_chamber_by_aswracing.jpg?direct&300|}} ((photo by aswracing of the XLFORUM http://xlforum.net/forums/showthread.php?t=1720575)) \\ | + | {{:techtalk:ref:svcproc:stock_thunderstorm_chamber_by_aswracing.jpg?direct&300|}} ((photo by aswracing of the XLFORUM https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-motor-engine/sportster-motorcycle-engine-conversions/160330-squish-band-clearance?t=1720575)) \\ |
- | + | ||