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Old 05-29-2010, 11:31 AM
moronic_kaos's Avatar
moronic_kaos moronic_kaos is offline
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Join Date: Apr 2010
Location: Connecticut
Posts: 225
Default Lesson Learned - Be careful with Slant Heads

Was working on a friend's motor & saw that his slanthead was all cracked up around the sparkplug hole. Since we were trying to diagnose the location of an air leak, figured that would be a good place to start so I threw my straight head on there. Motor seemed real hard to turn at first but then it finally started turning but wouldn't start. Pulled the head back off & the piston had actually snapped the electrode off the sparkplug. Luckily, the piston doesn't seem to have a mark on it, but I can't find the electrode anywhere.

Upon further inspection, I realized the slanthead had a piston with a round top, and the straight head was flat on top. Meaning the round spot on the top of the piston was probably coming up higher. Replaced the spark plug with a shorter one and it runs fine (but the airleak is still there unfortunately).

Just thought I'd save some of you a headache...
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Old 05-29-2010, 02:11 PM
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Junster Junster is offline
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Join Date: Jun 2009
Location: Washington St.
Posts: 446
Default Re: Lesson Learned - Be careful with Slant Heads

The electrode if you were lucky went in the exhaust. If you weren't it went in the scavenging port and into the bottom end. If it's running well it's probably in the exhaust. Use some wd-40 with the motor idling. Spray around the bottom of the cylinder, the intake tube at both ends, the head gasket. If you hear the motor slow down you found it. (wd temporarily plugs the leak and is safer than starting fluid) If that doesn't work get a piece of kinda thick glass and pull the head. Use some 220 wet/dry sandpaper. Dip the whole sheet in water then it will semi stick to the glass and sand the bottom of the head flat. Keep the paper very wet. Slantheads are almost always warped a little. Even if you found your leak the motor will run better if you lap the head flat. Good Luck
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