81 YZ250 questions

[fuzzydnkn]

Hello, I have a 1981 YZ250, im trying to restore. I have the top end apart and just have a few questions, maybe someone can help me out :)
The piston and rings were a size to small... and when i took the cylinder off the piston had it seems like carbon build up on it..could that be the reason why?
Also, How do I know when I need to get a bottom end done, like the rod bearing? (Mine has a little bit of side to side play, but no up and down play)
Thanks, any help is greatly appreciated.

 

[IndyMX]

I'd suggest, and it's just my opinion, that if it's either been a very long time or you just don't know, go ahead and do the bottom end now. Then you know what you have and don't have to worry about it blowing up at a very bad time!

What do you mean the rings were a size too small?

 

[fuzzydnkn]

Well, i'm not that much of an expert or do i have the tools to do a bottom end.. so how much would that cost about

And the cylinder is bored 80 over (thats what the guy i bought it from "thinks") and the piston and rings are only the second oversize (.50 over i believe)

 

[ysr89]

The cost depends on where you bring it, it will be alot if you bring them the whole bike, but if you remove the motor and break it doen as much as you can, it will be cheaper. Less work for them = less money.

 

[fuzzydnkn]

Well, what I would do is remove the motor from the frame and give them that... I was thinking it would be no more then 400.....right?

 

[nwwrestler171]

i had my bottom end done to get the crank rebuilt it was 185.31 and that was this past winter but sometimes if u know people u can get it done cheaper and u need to find out the real size of the top end and if the jugs good put that right size piston in

 

[fuzzydnkn]

Well, I just looked at the rod play again, little side to side movement and no up and down movement....but...i noticed a crack on the front side of the rod....im guessing that now im going to have to get the bottom end done.. Ill post a picture of the crack soon after the cameras done charging. What is a good place to get the bottom end rebuilt. I looked at surf & turf racing ( http://www.surfnturfracing.com/default.htm ) if theres any other good places lemme know. And exactly what should i get done to the bottom end....
Thanks alot :)

 

[fuzzydnkn]

Actually im not sure if its a crack or if its part of the casting (my dad thinks its part of the casting)... but i have a picture anyways
http://i203.photobucket.com/albums/aa7/fuzzydnkn/100_0070.jpg
sorry for the blurry-ness
Thanks again

 

[IndyMX]

That picture is pretty useless...

Try getting one that's not so blurry that you can't make out what's crank and what's crankcase.. ;)