350 bigbear NEED HELP ASAP

[bigbear350]

hey im new to this site...so i got a 350 big bear, not sure of the year.... i bought the bike from my grandfather who lost the regi.. serail numbers are rusted and worn off, cant make it out.. so with that being said the bike started smoking so i waz forced to change the rings and vlave seals, so i kinda guessed at the year of the bike and i bought the rings valve seals and the 2 head gaskets and o ring for a 91? and every thing fit but the rings, they were to thick to fit in the little slots on the piston.. why for this? waz the piston changed or just the wrong year rings? how do i go about getting the proper rings? can i trace the searail number on the moter? if so were can i find the numbers on the moter? or will i have to buy a new piston and rings and bore it out?
thanks alot, bikes been apart for about 3 weeks so i want to get it back togather...

[50bmgshooter]

First, you have a couple issues here. You will need to have the tools to make some careful measurements. The original bore size was 83mm. I would guess that the piston is not stock, probably a wiseco and they used a thinner ring than the stock big bear piston. If you could show the piston to a experienced mechanic they would be able to say if it is stock or not.

If the machine was smoking you may have wear in the cylinde bore that needs to be dealt with, a rebore might be needed.

I will guess that you were unable to find the VIN, they don't rust away, well not that I have ever seen. It is on the LH lower frame rail just forward of the footpeg.

Good luck!