Helicoil a timing chain “tensioner bolt”???

Clayton

Clayton

Active Member
My terminology is probably WAY wrong but please see my attached pics. Has anyone ever put Helicoil in the threads that hold the cam chain tensioner in place? When I went to took the bolt out of my case the threats came out with it. Has anyone else had this problem before and if so how did you fix it?
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kirrbby

kirrbby

Well-Known Member
Aww hell. Sorry about that.
I would think a helicoil would work just fine. But it will need to be the RIGHT size...short. it can't protrude inside of the tensioner hole at all.
I might even be tempted to just replace that stud with...maybe a ¼" setup. It would take someone with a OLD CT kinda eye to ever spot the change.
That stud does a pretty small amount of work. It only ever needs to be snug...not too tight at all...same with the jamb nut. A ¼" tap might just cut right into that damaged hole.
For that matter, a ¼" tap might just cut right in to a 6mm/10mm nut too..? Even Pat might be fooled by that kind of magic.
 
Clayton

Clayton

Active Member
Right on, I’m gonna tinker with it a little more. Iv got a damn nice machine shop that I deal with a lot that may be able to weld it up and re tap it for me. If it could be done I’m pretty sure they could do it. I have faith it can be fixed.
 
kirrbby

kirrbby

Well-Known Member
Oh ya...it's definitely repairable.
As far as it goes, you could probably just plug the hole, and put a auto adjust type tensioner in there. I don't see why not.
 
OLD CT

OLD CT

Well-Known Member
There is a little section for the o ring to seat, you don't want to mess with that. If you do a tensioner change, get the matching plug for the bottom to go with the setup. It is a little different.
 
kirrbby

kirrbby

Well-Known Member
OLD CT said:
There is a little section for the o ring to seat, you don't want to mess with that. If you do a tensioner change, get the matching plug for the bottom to go with the setup. It is a little different.
Click to expand...

Very good catch. I forgot about HOW that thing seals. That might be a problem...if the threads for the helicoil are too big, they would cut into the sealing area.
 
dirtbkr188

dirtbkr188

Active Member
The microfiche does not state the thread size of the adjusting bolt, but does list the jamnut as being 8mm, as seen HERE.
 
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kirrbby

kirrbby

Well-Known Member
They are m6x1. Same as the case screws, etc.

It DOES look like a helicoil will work fine. The sealing hole is just under 8mm. The OD of the tap for MY helicoil set is 7.3mm...so it clears the sealing hole. As best I can tell, you will need a helicoil insert that is 9mm long or less. when installed. MY kit, came with 9mm inserts.

I think it should be no problem. I would probably drill with a drill press. Then be cautious to run my tap in straight. I wouldn't be afraid to do it myself tho.
Always use plenty of oil when tapping aluminum. And drill with high speed and light pressure...and most importantly, sharp tools.

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Clayton

Clayton

Active Member
I’m going to buy a helicoil kit tomorrow! Thanks everyone who helped on this! This forum is so bad ass thanks to the people who chime in and help out. I really appreciate everything that everyone one here does. It really helps these little bike live on!
 
scooter

scooter

Well-Known Member
Just an FYI, the length of the helicoil is expressed in terms of the diameter of the thread being repaired. 6mm thread helicoil that is 1.5d long is 9mm in length, 2.5d is 15mm in length. You might also see reference to free running or locking helicoils. The locking one has a little indent on the thread that locks in against the bolt thread. The bolt will still come out but often time the helicoil comes out as well. Just pop a new helicoil in if that happens
 
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