Subject: Re: Kapow & Helicoil
Author: Ron Komoroski
Date: Mar 18, 2004, 7:57 AM
Post ID: 1716334748
Karl,
In the early 70's I MX raced Maicos, my first 400 used a 1/2" reach plug in
an aluminum head. With the number of plug changes necessary racing a
2-stroke, the inevitable happened & I stripped the threads. I tried regular
helicoils, and then the threaded inserts, (w/all the loctite type products
available)-nothing really worked long term, after a while the insert worked
loose in the aluminum. On more than one occasion I be running a moto, gas
the thing & KAPOW-BDDDDDD-CHUF-CHUF-CHUF-KACHUF. Once I even saw the
plug/insert sailing across the track leaving a trail of smoke in a perfect
arc. In the end I had the plug hole heli-arced up, re drilled & tapped-then
sold the bike. The 501 Maico I ran later used a 3/4" reach plug & as I was
careful changing plugs, I never had a problem.
If I had to repair the plug threads in a Guzzi, I'd use the threaded insert
rather than a helicoil. With the insert, you're threading the plug into a
proper machined thread, there's no chance of the "coil" getting hung up on
some carbon during a future plug check..
Ron Komoroski