Help! Cracked Crank Case

[jandm'smom]

We bought a YZ125 back in December. Absolutely love it. We found a slight problem recently though. We were having problems with the bike, so we started checking it out. Found out it has cracked case. It has already been repaired by the previous owner, and it cracked again. It is cracked at the oil fill, and it is approx. 3 inches. Question is, is this repairable? If so great where shall we begin. I have a trusting individual that welds, but not sure with it being that close to the fill, and that long if it is possible. If not any idea's on where to get one, other than Yamaha?

 

[nickyd]

It can be welded - I have seen some awful things be fixed by my welder - he is one of the best in my opinion. for the drain hole, he could always build the weld up and then cut new threads - have seen that done. search **** for cases if you don't feel comfortable with that

 

[chevy383cid]

Sure, weld it!! On my 98 yz The case side can be unbolted behind the fill hole>take it apart and have him weld it building up in the thread area ( make sure that he cuts a V in the crack so the weld will melt in properly)and get him or a machine shop to burr the area and cut some new threads. If I had my guess, It was not welded through the threads last time and the crack slowly started opening back up!!

 

[Tdel]

A little JB weld or PC-7 will do the trick for the short term

 

[Badgadjit1]

i blew the inner rod bearing out in my yz, the metal got into the outter parts of my flywheel and natually stuck the motor hardcore and i had a piece of my crank case split on the under side of my motor, nice little chunk about half the circumference of a dime. Knocked it kinda back into place and had it tig welded, then i filed and sanded. Holdin for 2 years now. Just ogtta be careful that the welding doesn't melt the case.

 

[jandm'smom]

Thanks for all the info. We will be welding soon.

 

[Lokair]

Cracks in cases are ussually grinded to a V and then at the end of the crack I drill hole(ussually 1/8 in size to stress releive the surrounding material) this will keep the crack from spreading after the fix. My Machinist has welded a few cases and such and only charges like 20-50$ for such a job. If he does the prep like 60-80$.
Good luck , and happy riding
Lok