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HELP - Stripped thread on valve cover *&%$£!!!!!

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Hi guys.

I checked my valve clearances this evening and they were ok (0.15mm inlet and 0.23mm exhaust).

Trouble is, when I was putting the magnesium valve cover back on the engine I stripped the front right thread with the allen bolt! I was very cautious to not apply too much pressure and the thread stripped before I even started nipping up the bolts!!! I guess the thread might have been damaged by the previous owner/mechanic.

Anyway, my questions are as follows:

1/ I put the rest of the bike back together and started the engine for a couple of minutes and the seal on the top seamed to hold - not oil leaks or noises from the engine - will it be ok to ride 10 miles to a mechanic?

2/ I guess the long term fix will be a heli coil - I know I need to drill out the original thread and then tap in a heli coil - can this be done easily? Any advice from others people who have had the same problem? What size coil set will I need if I attempt to do the job myself?

Thanks in advance.

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From memory M6 is what you need.

Yes you do need to drill first, unless you really pulled the thread out.

It will leak, so don't go far.

Don't know where you are, but I have an M6 helicoil kit.

Neil. :applause: :applause: :lol:

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Make sure you get the right pitch thread for the 6 mm size, I think it is 6 mm 1.0 pitch. Better to check the original screw with a thread guage to make sure you get correct size. If the thread stripped before you even put the bolt back in, you could probably get away with just chasing the threads with a tap.

Don Hopkirk

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Standard M6 is a 1 mm pitch, it only changes on "special use threads" usually known as metric fine.

M8 is the starting point for metric fine threads*, M8 fine is a 1 mm pitch, Standard M8 is 1.25 mm pitch.

Good point though Dhopkirk.

If you need any info on threads, a good place to start is a ZEUS book, available through engineering supplies.

Neil. :applause: :applause: :lol:

* Unless it is a manufacturer's special thread.

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From memory M6 is what you need.

Yes you do need to drill first, unless you really pulled the thread out.

It will leak, so don't go far.

Don't know where you are, but I have an M6 helicoil kit.

Neil. :applause: :applause: :lol:

Thanks guys - I'm in Northampton FYI.

Gonna have a better look today - like the idea that if the thread is already out I can get away without drilling. Anyone know who sells Heli Coils in Northampton on a Sunday?

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Just been reading some of the other posts on this problem - can someone please confirm if the top cover on the engine (3 bolt cover) is a 6mm or a 7mm?

Need to tell a garage to order me a 7x1 or a 6x1 (which they have in stock)

Thanks,

Matt

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