I'm buying a 300ex with an aftermarket cam and i have a quick question. The chain broke and slammed into the crankcase. I haven't checked around yet (or even seen the damage). Do you think i'll have to totally disasemble it to have it welded? As in take it in, in half? And do u think its possible to JB weld it if its just a small crack? How much compression does the crankcase have, if any? Appreciate any advice.

 

I've seen guys have them jb-welded and welded while the engine is still on the bike.May depend where the break is if it can be fixed while still on the bike.

 

A friend of mine threw his chain and it knocked a nickle size hole in the side of the block where the chain shroud bolts to it. he took it home and jb welded it and hasent had a problem, that was over a year ago. Jb is very strong we used it on form equipment all the time, If it's a small crack I wouldn't worry about it just put jb on it and enjoy your new bike.

 

i bought my warrior with a 1/4 inch hole in the crankcase, not very big. i roughed up the edges with a dremel and cleaned it real good with carb cleaner and used the ORIGINAL JB weld. when it dried i ground it nice and smooth and you cant even tell its there and holds oil 100% no poblems. definately recommend it.

 

I had a 250x and J-Bweld is all that held it together

 

I had a guy sell me a warrior that had JB weld over a crack on the block. Turned out it was covering up the serial number since he stole the darn thing. In this case the JB weld didn't work as I found it, chipped it off and got his a$$ arrested.

Other than that, JB weld usually works great.

Jaybee

 

lmao jay. Thanks alot guys for the quick responce. I've had some good luck with jb myself. Like i said, havn't seen the motor but i did see the bike. The engine is already off. I think i'll bring it home and look it over. Hopefully no chunks fell inside. Didn't think jb weld would get such good reviews, definatly worth a shot.

 

I always carry jb weld for emergency repairs on the trail and have had great luck using this on other peoples bikes. However, in your situation when looking to buy a new used bike I would shy away from getting a motor that you know has broken cases. Anyone who lets chain get so loose that chain breaks or comes off and cracks cases is not a very good wrench. Look close and you will more than likely see many signs of poor maintenance and rough service.