Piston/Valves Xr650r. Photo's

Just had my top end done at Precision Concepts. My bike ran and started great. My only complaint was that the intake valves were tightening on a regular intreval.

This is at 13K miles.

Piston.

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Exhaust valves

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Intake valves

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This cost about $950.

Thanks for posting the photos, doesn't look too bad considering the mileage. I'm thinking about getting mine done for the same reason and I want to find a good shop I can trust with my old girl.

It's obvious from the back side picture of the intake valves that one valve guide seal was leaking allowing oil into the chamber. That is the sludge/crud on the back of the valve. When oil get's in, it can easily cause detonation through the forming of ash/carbon deposits. It also looks like you were running a high compression piston.

If I were a betting man, I would be pointing the stink finger at a bad valve guide, worn valve stem, bad valve guide seal, or a combination of those elements.

wow,thats alot of money.did you dismantle and assemble it yourself?

I just did my xr650L and the new honda piston,honda gasket set,honda valve seals only cost $250.00 and the bore job and valve job was $125.00 maybe living in WI does have its advantages( we get shafted on the short riding season)lol.

That seemed to be the going rate around here. I dropped the whole bike off and they did all the labor.

The service guy who worked on it said it all looked normal. He said it didn't need a piston but since I already paid for the labor, I had them put one in.

It's interesting, I rode the bike yesterday and it didn't feel any better/stronger. It did seem to rev a little slower.

Also, they claim the UNI Air Filter is the reason for the worn intake valves. They seem to think the stock filter is the way to go.

???? Worn intake valves????? How were they worn? The only damage I can think of that MIGHT be caused by lack of filtration might be damage to the head where the valve seats against it, and on the edge of the valve where it seats against the head if dirt were to be trapped between the two when the valve closes (not probable). Other than that, not much of a chance that your air filter caused the valves any damage.

Cylinder scoring, excessively worn rings, and piston skirt scoring is often a sign of dirt getting into the cylinder (past the air filter).

???? Worn intake valves????? How were they worn? The only damage I can think of that MIGHT be caused by lack of filtration might be damage to the head where the valve seats against it, and on the edge of the valve where it seats against the head if dirt were to be trapped between the two when the valve closes (not probable). Other than that, not much of a chance that your air filter caused the valves any damage.

Cylinder scoring, excessively worn rings, and piston skirt scoring is often a sign of dirt getting into the cylinder (past the air filter).

Imperfect filtration is a significant killer of intake valves on these and similar engines, in my experience. The best intake filtration you can manage is the best thing you can do for the lifespan of an intake valve (aside from regular checks/ajustments).

And yes, it is tiny specs of dirt that get imbedded into the valve sealing surface that causes the harm.

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