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Title: Cross threaded/fouled spark plug threads Post by: Slide Panda on May 10, 2012, 05:30:20 PM 2000, M900
So it seems I cross threaded my spark plug in the horizontal cylinder. It's out now, but won't go back in (duh). I've had as odd a peak as I can with a light and naked eyes and it appears the problem appears near the external side Obviously a problem there's a number of paths to pursue to a solution, so I'm coming to you guys for 'the best' 1. Get a normal tap, oil it up and try to recut the to threads where things seem to have gone funny, with the head in place. Seems a bad idea as you're turing the cutting tool into the head and getting the cutting faces lined up on the fouled threads first. 2. Get a special spark plug re-threading tool for $50+ like so: Link (http://www.google.com/products/catalog?q=12mm+spark+plug+tap&um=1&ie=UTF-8&tbm=shop&cid=15460031233718059869&sa=X&ei=i2msT4zsK4-49gTft6XTBA&ved=0CJ8BEPMCMAI) And try to fix with the head on. - The tool has a collapsed cutting head that you insert then expand and back out. Cutting from the inside out. So you draw (hopefully) draw any shavings out. And you engage with good threads first. 3. Get surgical and remove the head, and clean the threads from the inside out and ensure no shavings get inside. - most time and fuss intensive. So I figure option 1 will end in tears, or has the highest chance. Option 2, never used a tool like that, so I'm not sure how well they do Option 3. I know will work. It's just a big hassle. Thoughts? Title: Re: Cross threaded/fouled spark plug threads Post by: ducpainter on May 10, 2012, 05:39:30 PM Grease the tap...
give it a go. If it doesn't work you can deal with a time-sert or helicoil... you decide which. Title: Re: Cross threaded/fouled spark plug threads Post by: suzyj on May 10, 2012, 06:26:03 PM Ripping the head off is really, really easy. Just pop the belt off, undo the header, pop the throttle bodies off (no need to undo the throttle cable as you're only lifting it half an inch), then undo the 4 head nuts and slide it off. Don't even need to drop the oil.
Title: Re: Cross threaded/fouled spark plug threads Post by: Slide Panda on May 11, 2012, 06:31:27 AM Well I found that back tap for about $20 after a little more hunting. So I'm going to give that a roll first.
Just worried about shavings in the head :( Title: Re: Cross threaded/fouled spark plug threads Post by: Big John on May 11, 2012, 08:12:14 AM Done many times both ways. I would not do grease method in this case because there is risk and these heads are too easy to pull and parts too expensive to accept that type of risk. Never tried back tapping.
Title: Re: Cross threaded/fouled spark plug threads Post by: ducpainter on May 11, 2012, 11:14:53 AM Well I found that back tap for about $20 after a little more hunting. So I'm going to give that a roll first. I've tapped a bunch of plug threads with the head on (both 2 and 4 stroke) and grease on the tap and never had a problem.Just worried about shavings in the head :( YMMV |