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Discussion Starter · #1 ·
So a couple of months ago I bought a non running 78 CX500 off craig's. It had been sitting, but after a few small things(new gas and new plugs and she was running that night) brakes, cables, fluids,ect. I was f*****g golden. For a minute. One good long ride and a few short ones and she left me stranded with no spark. After going through the useual suspects, i need a CDI. While saving up for a ignitech I figured I would do some things I was saving for winter. task 1. clean carbs easy enough (super fuzzy i can't wait to ride it when shes getting the gas she deserves). task 2. adjust valves(super tight. good. I'm not needlessly taking things apart.)then it happens. while tightening the right valve cover the second bolt starts to get a little torque... and... loose.. removed the cover, threads are in about 20 pieces. So does anyone know if a custom head will work? There seem to be more around that I could use for parts, and some other cosmetic things I'd like to swap.
 

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Engine block parts are identical if I recall, but how hard can it be to clean out what's left of the old bolt?



See if a strong magnet will attract the bits/pieces and, if so, magnetize a small screwdriver and go at it.



You can also magnetize taps rather easily with a strong magnet. Ineither case just stroke the screwdriver or tap from the big end end to the tip about a hundred times, always going just in one direction and lifting the magnet off before you start the next stroke.
 

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Why not heli coil it? Or howerver its spelled. The guy I bought my bike from did the same thing and just replaced the head I always wondered why he didn't just helicoil it.



Any reason why a helicoil set wouldn't work?
 

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Yes Yes Helicoil (or another similar brand).



I have done this with this exact thread. Works great.



THe thread is M6 x 1.



Mike
 

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Before replacing the head there is another fix. This is a 1/4-20 bolt 3" long and another threaded portion welded on at 90 degrees. This works good as new on my bike.







 

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Linny,



that is quite a piece of lateral thinking.



However if it is just the thread in the head that is gone, the helicoil is a 5 minute fix and is as good as new.



Mike.
 

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Discussion Starter · #10 ·
Sorry I'm slow to respond the man keeps me down at work with websense. I didn't think a helicoil would work cause half of the threads are basicly perfect. I thought the drill would want to walk all over. I guess I should try that before the L-bolt-through the head-and nut repair. the worst that can happen is I ruin a ruined head.
 

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Sorry I'm slow to respond the man keeps me down at work with websense. I didn't think a helicoil would work cause half of the threads are basicly perfect. I thought the drill would want to walk all over. I guess I should try that before the L-bolt-through the head-and nut repair. the worst that can happen is I ruin a ruined head.


It won't be ruined. There isn't much aluminum there. If drilling out for the rethread doesn't work (cracks) use a needlenose and break out the side toward the sparkplug. Then a 1/4 inch hole through the side. Good luck with your repair.
 

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You probably know this but I will post it for the sake of anyone reading this in the future that may not. When drilling the old threads out be sure to place a rag or something over any exposed area of the head so you don't get metal filings into the engine.
 
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