I have had three big bears 350cc and the newer 400cc all of them developed smoking at start up. This is due to a leaky valve guide seal.. It is very common and anyone at the yamaha shop that you tell your story to should know about this issue. If it only smokes after it sets a while and then stops it is more than likely this seal.

My first big bear it started after only owning it 3 months no idea mileage was no gauge the next two were around 600-1200 miles before it happened.. If it makes you feel better I don't think it affects performace at all and it doesnt affect the reliability at all. My big bears were all pretty much bullet proof.

 

Thanks for the feedback. Did you ever bring any of your bikes in for the problem? I've made an appt for after hunting season to bring it in. Not sure if i will yet tho. Like i said letting someone crack open the head over a benign issue may open a bigger can of worms. Motor runs awesome and only smokes for 20 seconds after its been sitting and its cold out.

 

I never had a decent warranty so no shop visits for me... but im thinking its a pretty easy job . Yes they will have to open it up. I too share your fears of letting people get into my motors .. the **** never seems the same after.

 

It sure doesn't. I forgot to mention it only smokes on the first startup of the day. Matter of factly it didn't do it the other day and it was like 30 out. I'm going to triple check my oil level next time and make sure i didn't put alittle to much in but it looks good on the dip stick.

 

hey man make sure you are not over full on oil.

 

Plus one on oil level also check oil to make sure your carb. hasn,t leaked fuel in engine oil[ due to hauling with fuel value turned on or water has got in fuel and float value not seating correct. Yes check oil level, then if evertything okay, do you have any squeaks or rattles on cold starts? in oil filter in correctlly? I think there are an oil pressure bolt in top of head maybe 10mm head around the top right of head i think, see if oil comes out of it after removed and start up cold... you have some slag from engine being new and not letting oil thru head when engine cold, but still head may need removed. IMO if i was nervous bout top end being removed at dealer, then check history of dealer servicing dept. and ask to see certifate of training, ask if they stand behind there work, may have to replaced value guide aslo....If was me with my training i would remove exhaust system and carb intake modifold and let engine sitt maybe a week ]with ports plugged up] then take an flash light and look into ports of head to see if any oil is on back side of value or values, This is an great way to see if stem seals are leaking, they willbe oil on back of value, if so the engine will smoke until oil is burnt off. But you have to remember most warranty will not covered if engine been tapered with,It just away to satifly your concerns.

 

I'm sure it's fine , sounds like your machine sits alot...letting the oil leak down from the seals a bit. Just run it BIG BEARS are soooo tough it's nuts..

 

I know this is an old post, but I'm curious what you found to be the problem? My BB is doing the same and I'm thinking valve seals but unsure.

Thanks

 

all my yamahas have done it since i bought them and have put over 1000km on my 97 350 wolvy and 02 400 bb and my ytm200 i just aquired does it and im sure it will untill i kill it. i thought it was just condensation in the exhaust forming and freezing when parked

 

I wouldn't worry about someone cracking the head off.They have tests they can do to narrow down your problem. It is a shop your planning on taking it to?I like the idea of trying a lighter oil. Keep us posted.