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So I over-tightened and stripped the threads on my RM250 oil drain. Went to the auto parts store to try and find an oversize self-tapping plug. Checked three stores and none had the correct size but an employee talked me into trying a m12-1.75 vs the m12-1.25 that it takes. He said since its a bigger thread pitch it will cut new threads and should hold tight. Don't know why I listened to him but I tried it and it's still stripping. Now I'm stuck, should I try and find a double oversized m12-1.75 since that's what the threads are cut at now, or do I get it drilled out and have a hell-coil installed. If I installed a heli-coil would I use the m12-1.25 that it was originally, or the m12-1.75 that it is now? I don't have the tools or knowledge to do this myself so I will probably end up taking it to a shop, but I imagine that's going to be expensive so I figured I'd check here first and see what I should do.
http://www.timesert.com
The kit isn’t cheap, but comes with the drill and tap required.
I put one in a stripped fork leg on my Vintage RM125 (for the axle). Worked a treat.
The best fix is a new case and that is the only repair I would ever recommend.
How ever you can strip down the cases and take it to a welder and have the case welded, drilled and tapped for the plug. The issue there is the thin case material will most likely warp the case.
Paw Paw
Edit: So my reply wasn't totally worthless. I would be doing what Paw Paw says and buying a new case or having it welded and tapped again.
All you do is drill your hole out to the size the kit specifies. 2nd step is tapping the hole. Then use the helicoil install tool to twist the insert up in there. Its super eazy and takes 10 mins.
The Shop
Paw Paw
Similarly there was about a 1/4 inch of material, than a small basin, than more material above that. Timeserts seemed to be a good idea but I was nervous that material would collect in that small basin because the Timeserts are solid all the way through, which wouldn't allow all of the oil to drain out of the case.
Helicoils made me nervous because of the lack of material.
I ended up drilling what was there and retapping to the next bolt size, it worked great - err good enough to hold at least. However I did sell the bike a short time later as I was tired of dealing with all of these 'gotchas' from the previous owner.
SOMETIMES you can use an american thread bolt or drain plug. The SAE threads are usually slightly larger than metric. Once you find the right size buy two of them and use a grinder to turn the bolt into a tap on the end. Put three flutes.
Make the bolt the actual tap and go slow, it will cut new threads and tighten strong.
When drilling and tapping I would put a air blower taped so its just blowing a little inside the motor through the crankcase breather hose so it blows the shavings out as you are taping.
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