I have a 2001 TRX350TE - Rancher. Just got it. It runs ok and doesn't make any bad noises but it has a good amount of blue smoke when running. Took apart top end. No broken rings, piston and cylinder look good. Valve seals aren't broken. There is a some caked oil deposits in exhaust port and on both valves. I can't see any gasket problems or cylinder head leaks etc. I will just do valve seals , new std rings with a quick hone and new gaskets unless someone out there think it could be something else.

 

Did you do a leak down and compression test before you tore into it???

 

No, I didn't because I didn't have a low power issue. I should have ( I do have the tools ). Jumped the gun, too late now. I think I'm at the re-ring stage at this point no matter what. This motor is too simple.

I did find that oil level was high...

Anytime I had a smoker like that was when I overlapped an oil ring on assy.

Are these motors prone to valve seal or ring problems??

 

Might as well do all the obvious stuff while you have it apart!

 

You have a valve guide and or seal problem. The deposits on the valves is a giveaway. Honda use to use really crappy metal in their valves a long time ago. Still the case? I have no idea?

Mic the valves and split ball check the guides REAL well.

I do agree with Recon..........if your this far down..........might as well make it real good unless your really hurtin for $$$'s.

 

As far as checking a motor before teardown, I don't think a compression test or leakdown would neccessarily find an oiling problem. You could have good compression/compression rings and tight valves, but have bad guides, broken or worn valve seals and or broken oil control ring. The cylinder could be bad but in leakdown you can only check at TDC. That being said if I had a bad leakdown it would have justified a teardown. Teardown still seemed like the the thing to do than to just dilly-dally around. I think the valve seals might be suspect but I think an oil burner would end up with deposits on exhaust valve as part of the buring process. I'll check the valve stem OD as well as guide ID.

PS: I am a machinist by trade and also worked in a automotive machine shop. I appreciate any advice but I guess I was looking for a answer like " Oh yeah all those TRX's have bad valve seals." kind of answers.

 

Let us know what you find out.

 

Ok....

Piston rings are the culprit..Top ring .020 end gap, 2nd ring .050 end gap, oil rings
.100 end gap.

Piston skirts look ok. I don't have a 3-4 in mike but it looks like piston to wall is about .002 max. Usable.

Funny thing , OD of piston measures +.25MM - I don't see any markings on piston for OS but I will get +.25MM rings. Good thing I just got the manual in the mail today. It's got all the specs!!.

Crankshaft is tired. Small end of connecting to piston pin is a little wobbly. Within specs. Piston pin ID to pin is tight. Pin measures like new. Id of rod is on max limit.

Head is ok. Valve stems mike like new and no leaks with solvent test. Exhaust valve is a hair loose but I know that exhaust has a shade more clearance. If I put intake valve in exhaust guide it's tight. (Intake valve is .001 bigger).

This is a friends ATV that he bought low dollar for daughter. He only wants it to run and not smoke out the neighborhood. If the crank hold up I think just re-ringing it will do the deal. I'll clean the head, lap the valves, new seals, re-ring and ball hone.