2006 Yamaha 350 Bruin

[JunkerG]

ATV smokes badly when it is cold and the choke is used, it won't start without using the choke. When it warms up, smoking stops or is at least not appearent to me. When it is warm and started there is no smoke. If I remember correctly it started smoking a little bit before mechanic adjusted the carb.

ATV would stall out when climbing hills. Man drilled out something and adjusted the mixture screw 3 turns out. Now I can kill everything within 5 acres with the smoke I create.

I have noticed oil and gas dripping from the rubber adapter where the carb hooks to filter box and there is some oil in the bottom of the box. Do ATV's have a PCV valve or something that would cause oil to be pushed up into carb.? Crankcase oil level is OK.

Within the last 2 years, mechanic has replaced cylinder, piston, rings, cam shaft, cam shaft chain and gear, valve guides. 1.5k in expenses and it still not right.

Does any one have any ideas?

Edited December 30, 2013 by JunkerG
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[oxidized_black]

is the smoke white or bluish? i know yamaha likes the choke on cold days too.

it is normal to have a little oil in the airbox, but not alot ... usually the vent hose from your airbox intake goes to underneath the fuel tank where another vent hose from the engine (crank) is connected ... this will explain oil in the airbox. i would say if its white smoke, its carb anf fuel related, blue could be rings or valve guides ... does the smoke smell of gas or oil or is it hard to tell the difference? did the bike smoke right after you had all this work done?

[JunkerG]

is the smoke white or bluish? i know yamaha likes the choke on cold days too.

it is normal to have a little oil in the airbox, but not alot ... usually the vent hose from your airbox intake goes to underneath the fuel tank where another vent hose from the engine (crank) is connected ... this will explain oil in the airbox. i would say if its white smoke, its carb anf fuel related, blue could be rings or valve guides ... does the smoke smell of gas or oil or is it hard to tell the difference? did the bike smoke right after you had all this work done?

I've had this thing back in for repair so many times I don't remember exactly when it started smokeing. He did the major things first and it wasn't smokeing when I picked it up. I ran it awhile and it developed a ticking noise in it. He said it was the tensioner for the cam shalf chain, not to worry. Then it started smokeing a bit and I took it back. He replaced the valve guides. It was better but still not right. I drove it awhile and started to get cold so I had to use the choke to start it. Smokeing got worse after he adjusted the carb. Took it back and he advised to start it without the choke. I told him where to go and left.

Sorry I gues I need to just answer your question. No white smoke, all blue and it does have a tingh of fuel smell, but not raw gas.

[oxidized_black]

im wondering when he did the rings, if he put one in the wrong way up. it happens and if everything is going good other than it smoking, i would suspect that ... just a b#@*h cause the head has to come off to find out ... maybe ck1999_400ex will see this and comment on it ... he was on earlier ...

[oxidized_black]

i am getting closer, i found an owners manual ...

2006 Yamaha Bruin 350 Owners Manual.pdf

[JunkerG]

I finally got this unit repaired. The head was ok. The cylinder had been bored out wrong. The piston was wearing on two sides, cylinder was egg shaped. They bored it out correctly to .060 over and replaced the piston and rings. Also put a kit in the carb. $650.00...I believe I have spent over 5k on this darn bike now. Trying to sell it now on Craigslist. First $2800.00 gets practically a new bike. Thanks again for help.