decompression shaft screw - hellicoil

need your help guys on the size of the screw that holds the decompression shaft (right side of the engine) . i ruined the screwing and need to get hellicoil, and the bike is not near me at the mom.

and one more thing , i never used hellicoil , any tips how to do it?

i just need to know what should i ask at the tools shop , what size/kind of helicoil as i dont have the screw with me.

and how do u guys helicoil ? do i need to take the valves cover out to do it or can i make it on the bike?


I did the same thing on my '00, there are only a few threads on that bolt so it is easy to rip those threads out.

I believe it is a 4 mm bolt, prob .75 pitch (?)

Anyway you can do it right on the bike. A little trickier than normal heli-coil jobs because it ain't a blind hole. I think I just cut the pigtail off the coil beforehand, threaded it in, and then held it in place with a small screwdriver while I removed the tool.

Hope this helps.

i posted thread a while back about this topic.i listed size heli coil and where you could buy just need to find that should answer most of your questions

ok , now u got me wrong, i saw someone offers a 6mm*1.25 and here u say 4mm*.75 . please help asap as i need to get it today from the shop (i dont have the bike or the screw with me).

all i can tell you is i was writing information with receipt for helicoils in my hand im sure of that because i posted k119's phone # incase anyone had trouble finding metric heli coils.

just in case you still dont trust me bolt1.jpg?bcB_i08AFRAX7RHz

hi freestyle ,

thanks for the help. but back then u said u used m6*1.25 and the manual shows m6*1. what do i realy need ? whats is the different between the 1 and 1.25 ? cause the person at the shop told me that the standard one is m6*1

thanks freestyle, and i trust u guys more

than any mechanic that i know....

they probably only had 1.25 when i was buying heli coils.i do know that they were a little long i had to trim the heli coil a little the way i recommend you take head off to install heli-coil.if you insist on doing it with head still on bike,try sticking a deepwall socket where decompression level fits the tighter the socket fits the better.the socket will stop heli-coil from threading in too deep.the reason most people are stripping the bolt is copper washer is worn to thin so the tip of bolt hit decompression shaft.bolt is supposed to fit in groove but stopping slightly before it hit shaft.

you can look up bolt size on microfiche at or .i almost forgot there is a seal for decompression shaft inside head you need to be careful not damage it.ive read a few post about oil leaks starting after helicoil fix.

thanks freestyle,

i heard that of the guys here just break the helicoil before it reaches to its end, to make sure its not far inside, what do u think ? hw can i stop it before its end?

and one more thing,

i dont think ill take off the head, any special tips how to do it on the best way?


Got the same problem 2 weeks ago, i just cut a new M8 and put a new Selfmade-Screw inside.

No problem anymore....

the problem with leaving head on when your installing heli coil will be all the metal shavings from drilling and tapping suck most of them out with shop vac but some will end in lip of decompresion shaft's wont take long after that to start leaking.with head off you can flush metal shavings out you have a much better view when installing heli only takes 15 pull head it costs $500 to replace head if you screw it up.why not take the time and make sure its done right.

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