CRF's Only Forums

New to this quality forum, however, I have been reading topics for several months.
After riding this weekend my bike was due for engine oil and filter change. When I replaced the drain bolt with a fresh washer and began to tighten I noticed a clicking/ slipping at or very near the bottom of the thread...
Further, the oil seemed to be leaking from the gasket between the crank cover and the case...I picked up a new bolt even though the original appeared fine hoping that the threads were damaged. That did not work. I laid the bike down a spotted the crack in my case. The LH crank case expands as a tighten the bolt and then gives exposing the crack...bummer.
How did that happen and what do I need to do to remedy?
My bike is a 2007 450X that I purchased in Fall 2014...this is the first of this problem. My buddy thinks I need to pull the engine and replace the LH case...thoughts? It is very unsettling to have my bike leaking oil and drained of fluids...
Please advise. Thx

Unfortunately it sounds like you will be replacing the case , the only other option (you will still have to remove the case) , is to find someone capable of welding it , it will need to be completely cleaned of any oil or grease , to be welded , and yes if its the inner case the motor will have to come out and be completely disassembled , if its just the ignition cover (Engine Oil not tranny oil) , then no you won't have to remove the engine , just remove the cover and either fix or replace , you will have to remove the stator assembly to do any repairs or to replace the cover as the new ignition cover will be without electrical components

Again , if its the tranny drain , then yes the engine will have to come out and be completely disassembled

As for the cause , at some point in its life (not necessarily you) , it was overtightened

Sorry for the bad news , but welcome to the site !!

thanks for the reply...is there anything else I should do while my guy is in there? Just looking for any suggestions...thx

To do it right ....It is as JD stated. Remove the case and either replace or repair.

Here is a option I would at least try -

Drain the oil and use a cleaner to completely flush oil from the case and crack. File a "V" in the crack. Rough up the area around the crack and clean, clean & clean the crack and area out. use a heat gun to heat the area up and make sure no oil migrates through the crack.
Mix up some 3M epoxy patch [ or JD weld if 3M is not avail.] to make a patch over the area. Let completely dry [ use a heat gun to aid the bonding process].

2-3 days later refill and reinstall the drain bolt with light torque to see if it will hold. I would use approximately 3/4 of the designated torque called out.

See if that works. 50/50 chance, but it's free and easy to try. Guarantee it's easier than pulling the engine down to square one !

If in fact it is the inner case , then while its "apart" , and if it has a few good hours on it (100+) , i would replace the piston , and timing chain , at the least replace the timing chain , make sure the valves are good (check the Intake shim size , if its near or at 1.20 on either side , then a valve job is imminent , if so i would recommend Stainless) , if its just the outer ignition cover , i would still replace the timing chain

When re-assembling put 1 full qt. in the tranny side , this is common practice with the X to avoid possible tranny issues (i do it in my 450R as well) . make sure your jetted for your elevation , and get some "Engine Ice" coolant , it will keep the engine temps up to 50 degrees cooler , which will help when slow going on a trail and will add to the longevity of the engine overall , just make sure to completely flush all the old coolant out (i use distilled water to flush the engine clean , as the Ice does not mix well with other coolants) , ....... that should get you started anyway

really good stuff...thx to all