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I managed to strip my right spark plug hole by forcing a plug into a hole thats been giving me trouble for a little while. Ive also just recently rebuilt the head and transmission and put it all back together and mounted so am trying to avoid breaking the chain or removing the engine at all. My question is is it possible to repair this socket with a helicoil type product without removing the head and where can i find the right tool for the job, ive never had to do anything like this and am scared that ive really messed it up, any thoughts or suggestions are appreciated, thanks

Josjosh
 

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If you just dumped a bunch of money into a top end rebuild then the only logical solution is to pull the head. it will cost a bunch of time and a cam chain master link, but at least you will not risk destroying a new bore / rings / piston etc.. there are a few tricks to minimize / prevent chips from getting into the engine when helicoiling a spark plug, and for a well worn engine I would probably chance it, telling myself a top end rebuild is eminent anyhow....

Just reread your post, did you replace the piston/ rings? if not then a lot of people say pack the tap with grease and go like that, force compressed air into the exhaust so its ripping out of the spark plug hole etc anything to keep the shavings out. then the last trick is to not loose the tab from the helicoil, aluminum shavings are a bummer, a hardened helicoil tab is disastrous.

The helicoil kit can be scored at any auto parts store, it comes with a tap, inserts and an installation tool, should run bout 20 bucks.
 

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When I bought my 450 it had a bum spark plug hole that I had to fix. I don't like to use heli-coil type inserts on spark plugs bc the bronze type seem to work better, stay at a more constant temp (the steel heli-coil can get much hotter that the head) and there is no tab to punch out. I had to tap the hole (packed with grease of course) then just run in the insert. It comes with the last few threads unfinished so that they get cold rolled and that's what locks it in place. http://www.timesert.com/html/sparkplug.html That's the link to the company that makes them. I think it costs a little more than if you bought just a regular heli-coil kit but in my opinion way better. When I was building nascar cup engines this is what we used if we had to fix a plug hole, and those made up to 870hp.
 

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I just heilicoiled a CB500F the tool with the coils cost me $60 at my local auto parts shop. Make sure you smooth out and de-bur the hole you drill, to ensure a tight seal of the spark plug.
 
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