help please
help please
I dropped my bike off in JUNE to get the jugs replaced, and a set of roller rockers installed. When I got it back two weeks ago, it ran good but rattled like h3ll. so I took it back, and they told me it was the lifters. So I replaced those. Then they said it was the roller rockers, so I changed back to stock... still no improvement. The bike has good oil pressure, and the top end is receiving plenty of oil. the screwdriver to the ear method shows the noise is coming from the front cylinder head. on the exhaust side. I have checked for exhaust leaks, there are none. The exhaust valve was replaced today (piston was in backwards). and after re-assembly it still has the exact same noise! I do not think it is spark knock, I retarded the timing on the front cylinder to the point where it was misfiring and it still makes the noise. it is a metallic knocking sound that starts at 2000 rpm and gets louder as you rev it. any help would be greatly appreciated.
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Joined: Aug 2005
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Tree,
I had a problem very close to yours. Long story short, the guy that reworked my heads did not do a great job. They ground to much off and that let the lifters slip. I had the same noise you have. The fix was new heads (zippers). I replaced the pistons because the ones from GMR Performance had some problems another story. The new heads fixed the problem.
I had a problem very close to yours. Long story short, the guy that reworked my heads did not do a great job. They ground to much off and that let the lifters slip. I had the same noise you have. The fix was new heads (zippers). I replaced the pistons because the ones from GMR Performance had some problems another story. The new heads fixed the problem.
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Joined: Dec 2007
Posts: 8,642
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From: Forest Lake, Mn
This is PURE speculation on my part, not being able to 'hear' the noise.
It is possible that the piston is contacting the exhaust valve. (Head machined out too much, decked too close or too thin a gasket are options here) Any evidence when you opened it back up? Sounds like your motor has some 'work' done to it, have the valve springs been changed? 2000 is not enough R's to cause valve float to cause contact.
If you have the time and where with all, put a second gasket on that front cylinder, try it again. It is time consuming, but KNOWLEDGE is our friend, and any gain is worth it for future reference, JMFUO. I always like to KNOW why something happened, not just replace parts til it gets fixed, read that "Cheap"
Good luck, and Please keep us updated here, THANX
It is possible that the piston is contacting the exhaust valve. (Head machined out too much, decked too close or too thin a gasket are options here) Any evidence when you opened it back up? Sounds like your motor has some 'work' done to it, have the valve springs been changed? 2000 is not enough R's to cause valve float to cause contact.
If you have the time and where with all, put a second gasket on that front cylinder, try it again. It is time consuming, but KNOWLEDGE is our friend, and any gain is worth it for future reference, JMFUO. I always like to KNOW why something happened, not just replace parts til it gets fixed, read that "Cheap"
Good luck, and Please keep us updated here, THANX
I have no clue what it could be.
I contacted the shop that did the work, and spoke with the owner. he said to bring it back in tuesday morning and he would tear it back down and start over. The part that baffles me is that there was no noise until they replaced the jugs. just a lot of oil being burnt. the only thing I can think of is maybe piston slap.
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