Case bolt hole repair

[brian kirby]

I have a problem with my 250 cases and I need some ideas on which way to go. The hole for the bolt that holds the swing arm pivot spacer that goes between the frame and the cases on the right side has a damaged Helicoil repair in it. The bolt will not stay tight, and the Helicoil is visibly damaged. Should I try a new Helicoil of the same size, or should I try to drill the hole to the smallest possible size larger than 8mm and thread directly into the cases with clean new threads? It appears that the drill you use to install an 8mm Helicoil is a 21/64ths, so the next size bolts would be a 3/8ths (9.5mm) or a 10mm.

Brian

[Keith Meatyard]

Brian, if you go the drill and thread insert route, take a look at a product called Keensert.  I have used them in different applications, and they use standard taps, have longer thread engagement than Helicoils, and can be removed later if need be.

Keith

Keith Meatyard

[Daniel P. McEntee]

I will second the motion for the use of Keen-Serts. They can take up more room than a heli-coil, but are much more durable and secure. I have in some cases (no pun intended)made a custom insert where I don't have room for a bought insert. If I need to replace a 6mm thread, I'l use a bolt just big enough to be able to bore it with the tap drill for the 6mm thread in a lathe. Then I'll tap it, take a hack saw or cut off wheel and cut a slot in one end for a screw driver to drive it in place, then cut it off to the proper length. Then I'll drill and tap the part for the external thread of the bolt I used. I use red Loctite on the insert when I install it, and have never had a problem or a failure of one of these. I just can't quite picture the area you are dealing with, but I would bet some sort of a threaded insert like the Keen-Sert will be a better choice.
  Good luck with it,
   Dan McEntee

[brian kirby]

Its this thing here, this is not my 250, this is on my 400 (it was easier to get to it to take a pic) and it has a stud in the case with a nut, the 250 has a bolt. Maybe a stud will work better?





Thanks for the tip on the Keenserts, I have never heard of them before but that looks exactly what I need.

Brian

[454MRW]

Keenserts are the way to go.
Brian, the bolt is wrong, it should be a stud. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R

[Daniel P. McEntee]

I'll vote for the stud also. Awesome close up photos! Almost scary!
   Type at you later,
   Dan McEntee

[brian kirby]

I suspect the bolt is in there because a stud would not stay. Cant believe I never heard of Keenserts before, the more I look at them the more I like the idea.

Brian

[slvrbrdfxr]

Brian
Another repair insert I've used on stripped spark plug holes is called a time-sert. It's a permanent fix and once installed won't come loose. Check it out at //www.timesert.com .
Dave McCullough