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needing some info and opinions please!! 97 yamaha big bear 350 smoking!

Jeremyv

By Jeremyv
in Yamaha ATV Forum

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Jeremyv Newbie

Jeremyv

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I just bought a 97 big bear 350 2×4 for the family to ride.. it's smokes real bad on start up and ride, the guy I bought it from said it just needs rings.. should I go ahead and replace the piston, rings, and hone and bore it if it hasent already been done? And where can I find the parts for a good price??? Also should I let my kids ride it the way it is, will it trash it out if they do??? Any info and options is helpful and welcomed, so please c him in!!!!! Thanks in advance!!!

Edited by Jeremyv
did not put make model and cc in subject
gears Contributor

gears

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Posted

I'd spend the money on a "new" top end. Rebuild yours.

First - tear it apart and CHECK THE CRANK/ROD CLEARANCE BEFORE ORDERING ANYTHING!!!

If it was ridden hard and ill treated you'll need to split the case - if you're able to do that yourself it's worth it. If you're paying a shop it's more money than a newer machine. You can check the rod play after removing the head & cylinder.

If the rod doesn't have excessive play, then I'd disassemble the head (you'll likely need an intake valve, they get pretty worn) Vesrah makes a cheap replacement, Get a top end gasket kit (again I use Vesrah - it comes with valve seals too) Have the valve seats cut (valve job) and replace the seals - don't forget to check the valve guides, too much play in the valve stem and you'll need more machining.

Wiseco pistons are nice but a bit pricey, there are lots of options including yamaha Have the cyl measured (or mic it yourself) and go to the minimum overbore.

I have seen where these have a wasted cylinder so you might have to get a new jug (ebay).

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