[shadetree]

my question is, why in the world did you use rancher parts on a trx300 top end ??. this blows my mind. you should put it back together with all trx300 parts. as for your smoking ?, it's going to be with the piston and rings. just because you have great compression ?, does not mean the oil rings are right ?. you need to pull it all back apart, check the oil rings down in the cylinder, but I would do this with the correct piston and rings, not rancher parts.

 

[shadetree]

Nothing more disheartening than having issues after a rebuild. I had a Suzuki Vinson last year that was smoking bad. I put new rings in it (nikasil cylinder so it still looked new) and fired it up and it still smoked. I went out and rode it hard for a bit and the smoking cleared up.

Rob

welllllllllllllll...lol, first..yes..chit happens !. but if a person takes their time, uses the correct parts ( or just makes sure parts will work ? ), then you worry about if your work was done right ?. I've been down the same road as the OP many times !, it sucks to rebuild something, and it not run right ?, or something else pops up, that you had no clue there was a problem, or what caused it ?, until you discover it !..lol. had this problem on an old trx350 rancher many moons ago, damn thing ate my lunch and some !..lol. little did I know, that the valve seat could work it's way out of the head once warm/hot ?. I replaced almost everything new with oem, and it still made a rattle when warm/hot ?..that's when I looked into this matter deeper, and found out Honda had a defective head on some of their trx350 rancher heads !..lol.

 

[shadetree]

To take all guesses out of the situation pull it apart and measure your piston to bore clearance, measure to see if the bore is out of round.

btw, you wont get a good gauge at whether or not your valves are leaking with oil, your best bet is using carb clean, brake clean, or even gas, dump it in the intake and exhaust ports and see if it seeps through.

My bet is the bore is out of round. even though its new, it should not consume that heavily.

I agree, something is not right with the bore/piston/rings.

 

[shadetree]

Nothing more disheartening than having issues after a rebuild. I had a Suzuki Vinson last year that was smoking bad. I put new rings in it (nikasil cylinder so it still looked new) and fired it up and it still smoked. I went out and rode it hard for a bit and the smoking cleared up.

Rob

welllllllllllllll...lol, first..yes..chit happens !. but if a person takes their time, uses the correct parts ( or just makes sure parts will work ? ), then you worry about if your work was done right ?. I've been down the same road as the OP many times !, it sucks to rebuild something, and it not run right ?, or something else pops up, that you had no clue there was a problem, or what caused it ?, until you discover it !..lol. had this problem on an old trx350 rancher many moons ago, damn thing ate my lunch and some !..lol. little did I know, that the valve seat could work it's way out of the head once warm/hot ?. I replaced almost everything new with oem, and it still made a rattle when warm/hot ?..that's when I looked into this matter deeper, and found out Honda had a defective head on some of their trx350 rancher heads !..lol.

Interesting and good to know.

The Rancher I've been rebuilding for my neighbor runs good now. It quit burping oil into the airbox (rings must have seated), carb quit leaking with a new float needle, and the disc brakes from a 420 Rancher stop it great.

It rattles like hell though, and I adjusted the valves before I ever tried to crank it.

He got a parts bike with this one, so maybe I'll swap the heads and see if it helps.

if the cam chain is good ?, and valves are set right ?, i'll bank on the valve seat coming out when it's warmed up !..lol. I know this for a fact !. I replaced cam, cam chain, valves were good as far as valve clearance , and it started up great, but once it got warmed up ?, i'd hear what sounded like a bad cam ?, bad cam chain ?, replaced all of that with new oem, still did the same thing. well, after it did it again, I shut it down, pulled the head, and after closely looking at the valve seat under the springs ?, I could see them sticking up ?..asked my bud at my dealership, he says '' oh yeah..those ranchers had a defective head on some of them '' ..now I learned something..lol.

 

[shadetree]

To take all guesses out of the situation pull it apart and measure your piston to bore clearance, measure to see if the bore is out of round.

btw, you wont get a good gauge at whether or not your valves are leaking with oil, your best bet is using carb clean, brake clean, or even gas, dump it in the intake and exhaust ports and see if it seeps through.

My bet is the bore is out of round. even though its new, it should not consume that heavily.

Will try with regular unleaded tonight. But i'm now thinking the cylinder as well. If I had to guess something is up with the cylinder, the compression rings have enough pressure to seal up or meet the imperfection, but the oil ring does not and it is leaving a film of oil on the cylinder wall. That would explain the good compression, and no draw down on the oil I put in the cylinder last night, but still having some blow by during the compression stroke. On that note though, wouldn't the compression rings be tight enough against the cylinder to scrape the oil off?

nope, the oil rings keep the oil off the cylinder wall, they have nothing to do with the compression.

 

[shadetree]

in other words, if your oil rings are bad ?, they will let oil slip by, and bleed out the exhaust, the compression rings will not stop oil from getting by, this is why your getting a smoking engine.

 

[shadetree]

Don't do alot of rebuilds but can these problems be attributed to the oil ring being installed up side down? I know one side of them is rounded and the other sort of cupped to scrape oil off the wall.

nope, impossible to install oil rings up side down, the smaller rings will go either way, then you have the center expansion ring, it too will fit on either way, no way of installing them wrong ?..butttttttttt !!!!!!!!!!.it is posb to damage the oil rings when installing the cylinder and piston !..lol.

 

[shadetree]

i'd rather toss 20 bucks at a motor, instead of 600 like me !..lmaoo.