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34 Posts
Over the weekend I found that my spark plug was seized. When it came out (warm engine – bad idea), the top set of aluminum threads came out of my head welded to the steel spark plug. In assessing the damage, I cleaned up the spark plug by filing off the stuck-on aluminum with a needle file. Then I carefully screwed the newish-looking plug back in without tightening it too much just to check the thread and the fit. Unbelievably, the plug seized the instant I tightened it and when I tried to coax it back out, the threaded steel base broke off 2/3 still in the head! Gah!
Okay, not terribly difficult to pull the head and work with it on a table. I tried filing the steel plug base that was stuck in the head in half but that did nothing – it wasn’t too tight, it was just seized at the molecular level so I had to drill it out. Don't ask how I know that a common M10-1.5 helicoil kit won't work. The stock plug is a M10-1.0 (fine threads). There are plugs that are M10-1.25 (medium threads) but no M10-1.5 (coarse threaded) plugs that I'm aware of. I looked around and couldn't find a M10-1.0 helicoil kit. Maybe a shop would have a comprehensive Time-Sert repair kit with the right insert but I just dived in and ordered the Trail Bikes 143cc Big Bore/Race Head V2/manifold adapter kit direct from TBparts.com.
My advice – 1) Only remove spark plugs from a cold aluminum head and 2) Always use anti-seize paste on plugs going into aluminum heads. I’ve changed dozens and dozens of spark plugs and found one seized like that, especially not on a new bike with under 500 miles on it. My habit is to always use anti-seize paste on my plugs and I’ll damned sure do that every time from now on.
I'm not sure that the plug was ever out from the factory. I bought it at 220 miles with Chimera/Yosh/Bazzaz already on it. The Bazzaz map was only the default map which is kind of lame so I updated that straight away. I also noticed that the rear axle had been heinously over-tightened. The previous owner, a Delta A&P mechanic, must have cranked down on the axle like it was a lug nut on a 747.
Okay, not terribly difficult to pull the head and work with it on a table. I tried filing the steel plug base that was stuck in the head in half but that did nothing – it wasn’t too tight, it was just seized at the molecular level so I had to drill it out. Don't ask how I know that a common M10-1.5 helicoil kit won't work. The stock plug is a M10-1.0 (fine threads). There are plugs that are M10-1.25 (medium threads) but no M10-1.5 (coarse threaded) plugs that I'm aware of. I looked around and couldn't find a M10-1.0 helicoil kit. Maybe a shop would have a comprehensive Time-Sert repair kit with the right insert but I just dived in and ordered the Trail Bikes 143cc Big Bore/Race Head V2/manifold adapter kit direct from TBparts.com.
My advice – 1) Only remove spark plugs from a cold aluminum head and 2) Always use anti-seize paste on plugs going into aluminum heads. I’ve changed dozens and dozens of spark plugs and found one seized like that, especially not on a new bike with under 500 miles on it. My habit is to always use anti-seize paste on my plugs and I’ll damned sure do that every time from now on.
I'm not sure that the plug was ever out from the factory. I bought it at 220 miles with Chimera/Yosh/Bazzaz already on it. The Bazzaz map was only the default map which is kind of lame so I updated that straight away. I also noticed that the rear axle had been heinously over-tightened. The previous owner, a Delta A&P mechanic, must have cranked down on the axle like it was a lug nut on a 747.
