multiple engine failures
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Stage II
Joined: May 2015
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From: Gillette Wy
multiple engine failures
I have an 07 soft tail with a 103 cid.258 cams 10.5 to 1 piston se heads match ported and flowed upgraded timkin bearing cam plate and oil pump.d&d fat cat 2 into 1 exhaust.Problem is I get scoring on both cylinders at 12 and 6 oclock positions.get the scoring same places after fly wheel swap and new pistons.Dealer has been in this engine 3 times in 2 years.Says I have to live with it .Looking for ideas as to what is causing this problem and why it cant be corrected.Thx
If you are seriously scoring the pistons and having compression/oil control failures, and all the machining was correct, the tune is correct, you're not abusing the bike etc etc, and everything is done right, this could be clogged piston jets.
I got a bike to repair after it has failed the pistons 2x by scoring the cylinders and pistons. The guy called uncle and asked me to look at it.
I found the piston jets were clogged with material that looked like someone had used a rag that shed lint to wipe down inside the cases while it was apart.
This is not common, but a failure at that component can take out a piston. I did notice it had higher than normal oil pressure at idle because the jets weren't popping open and bleeding off some pressure.
I got a bike to repair after it has failed the pistons 2x by scoring the cylinders and pistons. The guy called uncle and asked me to look at it.
I found the piston jets were clogged with material that looked like someone had used a rag that shed lint to wipe down inside the cases while it was apart.
This is not common, but a failure at that component can take out a piston. I did notice it had higher than normal oil pressure at idle because the jets weren't popping open and bleeding off some pressure.
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Stage II
Joined: May 2015
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From: Gillette Wy
thx for the reply.The scoring appears in the same exact spots even after changing flywheels, pistons and cylinders.The only parts that haven't been changed are the cases and those were split and bearings replaced and upgraded.I haven't been able to get more than 700 miles on a build and after 43k still have the factory clutch.I don't beat on my bike.no burn outs no hole shots .I also have a high frequency vibration,seems to be constant with engine rpm.
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Joined: Mar 2010
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From: Poolville
Some scoring is normal. You need to remember that is the way the piston pivots on the wrist pin. However if you have too much scoring then I would check my piston to cylinder clearance. It should be between .0015" and .0025". If it's within specs then it's normal.
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Joined: May 2015
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From: waterford mi
need more info are the pistons showing scuffing on the skirts or anywhere else piston manufacturer are they forged what are the starting clearences piston ring manufacturer overfueling issue there is clearly a problem the dealer clearly hasn't done there homework all they have done is cash your check. only a guess due to all the air fuel flo mods you are overfueling washing out the rings or to lean cuasing excessive cylinder temp fuel helps to cool the piston. in a two cycle the fuel is 75% of your piston cooling if it is to lean it will sieze or burn a hole thru the top of piston until you jet it correctly
Stage II
Joined: May 2015
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From: CA
Sounds like you have contaminates in the engine to me. They are very hard to get out. They can lurk in the oil cooler, or oil passage ways and even though you replace parts, they are still lurking. Don't ask me how I know. -Tutt
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Are these scuff marks on the front/rear of the cylinders?
We just had an engine here that had the C/L of the Timken bearing set, machined into the cases .056" to the sprocket side, causing the piston to load the primary side(left side) of the piston, and generally making a mess of the entire piston once the heat from the friction entered the picture.(the heat even cracked a cylinder)
4 other shops looked at this prior to it coming here......we found it, and then manufactered a custom ground precision spacer installed between the sprocket shaft shoulder, and the back of the in-board Timken, allowing the crank to center under the spigot bores properly.
The odd loading of the crank had it out-of-true by .011" also.
All good now, and running like a scalded cat as we added cylinder head work/compression and a Wood 8 cam to it.
Turned lemons into lemonade, once again.
Scott
We just had an engine here that had the C/L of the Timken bearing set, machined into the cases .056" to the sprocket side, causing the piston to load the primary side(left side) of the piston, and generally making a mess of the entire piston once the heat from the friction entered the picture.(the heat even cracked a cylinder)
4 other shops looked at this prior to it coming here......we found it, and then manufactered a custom ground precision spacer installed between the sprocket shaft shoulder, and the back of the in-board Timken, allowing the crank to center under the spigot bores properly.
The odd loading of the crank had it out-of-true by .011" also.
All good now, and running like a scalded cat as we added cylinder head work/compression and a Wood 8 cam to it.
Turned lemons into lemonade, once again.
Scott
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From: Central Illinois
If the shop is not thoroughly scrubbing the cylinders out after machining, you will get scoring after the engine heats up and the contaminates come to the surface of the metal. Put the cylinders in a bucket of very hot water with lots of dish soap and a bore brush. Scrub the cylinders out at least 5 times, including the oil passages, then blow dry and oil the cylinders.
I had a 1000cc Sportster seize up on me years ago on the interstate from contaminates coming out after a bore job. Never trust the shop to scrub the cylinders without confirming it.
I had a 1000cc Sportster seize up on me years ago on the interstate from contaminates coming out after a bore job. Never trust the shop to scrub the cylinders without confirming it.
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If you are seriously scoring the pistons and having compression/oil control failures, and all the machining was correct, the tune is correct, you're not abusing the bike etc etc, and everything is done right, this could be clogged piston jets.
I got a bike to repair after it has failed the pistons 2x by scoring the cylinders and pistons. The guy called uncle and asked me to look at it.
I found the piston jets were clogged with material that looked like someone had used a rag that shed lint to wipe down inside the cases while it was apart.
This is not common, but a failure at that component can take out a piston. I did notice it had higher than normal oil pressure at idle because the jets weren't popping open and bleeding off some pressure.
I got a bike to repair after it has failed the pistons 2x by scoring the cylinders and pistons. The guy called uncle and asked me to look at it.
I found the piston jets were clogged with material that looked like someone had used a rag that shed lint to wipe down inside the cases while it was apart.
This is not common, but a failure at that component can take out a piston. I did notice it had higher than normal oil pressure at idle because the jets weren't popping open and bleeding off some pressure.
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