Crank Case Bolt Mount Broken--Fixes?

Hi All

Have a broken CC bolt mount broken off from throwing my chain last weekend. This is one of the two bolts (bottom one is problem) that holds the front chain guard on an 06 WR450. Shaft was bent and had the dealer fix it...(honestly not sure the bolt mount was broken on the trail, but dealer denies any involvement! And at a minimum I'm sure the the chain weakened it since it jammed in the front sprocket pretty tight as well as snapping the chain guard (wish I was going slower))...hard to hold the dealer responsible.

So, is there a good way to fix it? Right now the dealer plugged the hole with silicon and basically stuck a long bolt in there, no threads to tighten up...I was checking torques on their work since I think they suck and I'll never go back to them...which leads me to the next question....

Where is the best bike maintainer in the San Francisco East Bay area?

Thanks in advance for any advice/help...Regards, KS


What a bugger.One way would be to heli-coil the hole if there is sufficient aluminium in the boss area.Heli-coiling is tapping the hole to a larger size(marginally) and installing a threaded insert. If you go this way. Put grease on the tap. This will catch any swarf from tapping. After installing the heli-coil you could loctitie a stud into place. This would then seal the hole and wouldn't have to be removed each time the sprocket cover was removed. Hope this helps. Let me know if this isn't what you meant and I'll see if I can suggest something else.

Helicoil or truecoil

Timo McKeown


In Aus we have heli-coil. I'm sure truecoil is the equivilant

Thanks much guys...

Figured it was a tough one since so few replies!...I tapped the hole that was remaining to an 8mm and used a rubber tube for a spacer with a 2.5 inch long bolt...pretty secure since I tapped it about 3/4 inch deep...lots of bolt buried in the cover...was lucky to have the hole so deep...

Was worried about "breaking through" the crankcase, so laid the bike over on the left side where I tapped and had no oil leak...changed the oil anyway, just to make sure no tapping shavings made it's way to a place I didn't want them....

Anyway, much more secure than what the friggin dealer did! Guess the best prevention is to avoid snapping the chain!

Again, thanks much...Regards, KS

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