When I purchased my GS a lot of years ago, I noticed that the had cover bolts were not original, they were some kind of dirty trick with washers and rubber seals that worked (no oil leak) but were awful to see. 

Fed up, time to rebuild. I was going to get some helicoils to rebuild the threads in the camshaft ABCD supports but I was surprised to find that:

- Support A and D (front left and rear right) have a M6 thread, and support B and C (front right and rear left) have a M7 thread.

I have a bolt that looks original... but it is M7.

Question: Are original bolts M6 or M7?
If they are M7.. then from where came my A and D suports with the M6 thread?

M7 is a very non preffered thread size. Are you sure that someone hasnt ragged it out to a 9/32 O/D thread. There is only about 0.14mm difference.

I've just ordered 4 new bolts from Suzuki.

If they are M6, I'll need 2 helicoils for those that were upperthreaded to M7.

If they are M7, I'll wonder forever from where came my A and D supports with M6.

Marc.

Original suzuki head valve cover bolts are M7.

I am wondering why my GS had 2 supports with M6 threads and 2 supports with M7 threads.

Now I have all supports with M7: 2 have new threads done, one has a helicoil, and one was OK.


Tomorrow is assembly day.

Finally got my camshaft supports fixed:

Two were M6 threaded. People at Mecàniques Carandell in Girona did a great job making M7 threads where there were damaged M6 threads.

One was M7 but was damaged. It was repaired at Rectificadora Reima. They didn't use an helicoil they installed a threaded sleeve and used heavy loctite to keep it tight.

Last support was M7 and OK.

Some photos of the repaired supports and the new head cover bolts (they are no longer black)



Since I had the valve cover out, I did the valve job:



One shim needed to be replaced. Left Intake was replaced from 250 to 245.



96000Km on the counter and ready to go beyond 100.000Km

I am still wondering from where came the 2 supports with M6 threads I found in my engine.