What do you do for stripped out bolt holes?

Stripped bolt holes seem to be a very common problem. I only have one bike that has all the original bolts and screws. Most often I find a few US threaded pattern bolts or screws used as a substitute for the lost metric one. If it had not been taken in and out too many times, I can sometimes get lucky by rethreading it to the correct metric size and get it to hold ok, but not always the case. Especially the flywheel cover bolt holes. I have one project with only one good hole, all others are oversized. Anyone had luck putting in a sleeve? Do they come that small? Thx!

As a suggestion, please stay with metric and use a metric insert of one type or another.

Most of the time, I use hell-coils. Kits are relatively inexpensive and work well. Sometimes, I use a Timesert when theres enough metal around the hole, such as the holes for the foot pegs or the spark plug.

allenp42 said:

As a suggestion, please stay with metric and use a metric insert of one type or another.

Most of the time, I use hell-coils. Kits are relatively inexpensive and work well. Sometimes, I use a Timesert tier's enough metal around the hole, such as the holes for the foot pegs or the spark plug.

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I tried a cheap insert in a spark plug hole without much luck. Gonna drill and tap out to a 12mm and upsize plug. But what about in the engine case where you cannot go thru it. Still work ok?

Measure the depth of the hole and make SURE you don't drill too deep. This applies to just about any hole you're repairing when there is bottom.....to somewhere you really don't want to go.

Pretty sure they make timeserts for oversize holes. I tend to stay with the original size as much as possible. Just a thought, most machine shops would probably repair that spark plug hole for less $$ than you can acquire the tools and do it yourself. I have only had one (spark plug) that needed the threads repaired so I farmed it out.

For sparkplug hole repairs, I prefer Timeserts. It does take a bit of skill/experience to get them perfect but they're well worth it. A f**ked-up head casting is a high price to pay.

I've had good results with Helicoils, but I farmed them out. The saving grace, in a worst case scenario is that an m10 Timesert could still be used, if the M10 helicoil failed. Once you go to M12, no more second chances.

For every other threaded hole in the engine, Helicoils work well and are cheap.

Gonna have to try the inserts on the side cover holes for sure. I will practice on my ugly 92 first though! LOL