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pointblaynk

yamaha big bear 350 4x4 smoking need help

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my big bear is smoking. a guy i know said i when it does that and i just replace the rings it will end up doing it again. he aslo told me i would need another piston and have to get it bored. would just replacing the rings and getting it honed fix the problem or what? any advise is appreciated thanks

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Honing and new rings is a quick fix. I would do as your friend recommended, bore and new piston, rings, etc. It will already be apart and for the extra cash $150 or less it will last longer than just new rings.

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If you just replace the rings and hone the cylinder it may quit smoking, for a little while. There's no telling how long it will work. If you want the long term fix, bore it, hone it and put a new piston and rings. While you have it down it would probably be worth a valve job or at least replace the valve seals.

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Around here it runs about 45 dollars. To cut the valves and the seats you have to have the correct machines. You could probably get away with just lapping the valves if your in a crunch for money, but it will require knowledge on how to properly lap valves.

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I agree with Yamaha468, it would be best to address the valves as well, since it is just as likely that worn valve guides is the problem. What year is the Big Bear? I merged your two threads since you posted the same question twice.

Edited by DirtDemon

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its a 1994 yamaha big bear 350 all time 4wd. atleast the guy i got it from said he thinks its a 94. ist there a way i can find out for sure what year it is? cause i looked for a sicker on the frame but its not there.

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What do the title and registration say? There should be a vin# on it somewhere. You could search the web for a vin# decoder, or call a dealer, they may be able to tell you what it is.

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If you have any kind of serial number you can bring it to a dealer and they should be able to tell you the year. Just make sure it has a clean past.

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i dont have the title. i just have a bill of sale.

No title and you can't find a vin#, you may have a stolen ride there.

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i know its not stolen i got it from my friend i grew up with i ended up talkin to the guy who they got if from which i found out was my friends grandfather. he used it on his land to ride around on. but he told me all about it. and its a 94. i got my cylinder bored. it was bored alread to .75 and the yamaha dealership said that it was so worn out the cylinder wasnt round anymore it was egg shaped. so the bored it to 1.00 now i just gotta get the piston and rings and ill be set. the guy at the dealership told me it would be best to open up the right side of the case and drain all oil out and make sure theres no dirt or grime sittin on the bottom of the case. so hopefully ill have it running again.

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