Spark Plug Thread Repair

I did an insert, not really a helicoil but the same general idea, in an outboard motor that I didn't want to pull apart. I took a shopvac and hooked it up to BLOW instead of suck and connected the hose to the exhaust, then rotated the engine until all the air was coming out the sparkplug hole that needed fixing. Did the tap with the air blowing all the bits out of the hole (and into my face). The engine was horizontal so gravity wasn't pulling the bits into the hole and it worked great. If you don't want to pull the head I'd try that and maybe lay the bike on it's side so the air has an easier time blowing the filings out.

I went up to my local auto supply and bought a heli coil repair kit. It came with a 1.25mm thread tap, and I was able to repair the treads of the #2 spark plug hole. I used your idea Blaine to put the vac on the exhaust, and was hit by the shrapnel in the forehead many times. The kit came with some new steel inserts that would require you to drill out with a 5/8" drill bit and put in the insert. I like this fix better than the old coil type, and I may do this eventually, but now it is working fine since I repaired it with the tap.

I would be afraid to do the helicoil thing without removing the head. All of those cuttings and snipping the helicoil... Maybe if you had a borescope and microsurgical instruments --- never mind! Just take off the head! You might just consider continued use if you can torque the plug on the "light end " of the torque range and it stays tight and doesn't leak. If you can do this, you can do the helicoil fix next time the head if off.

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