Jump to content
Sign in to follow this  

Stripped out threads on cylinder, looking for ideas on how to fix

Recommended Posts

"Dear previous owner, you should never own a motorcycle... ever."

 

What seems to be a recurring theme with this damn bike is that everything that could be wrong was which now apparently includes the blind bolt holes in the cylinder. Found an obstruction in the blind bolt hole directly in front of where the spark plug hole is so I fished it out and chased my 9x1.25 taps down to clean out the threads. Torque sequence on the cylinder head was fine at 20 Nm, 25 Nm, and 30 Nm. When I went for the final torque of 36 Nm, per the service manual, the bolt lost the bite and I knew the threads on the bore had gave up the ghost. My guess is that the POS previous owner torqued the bolts to 36 ft-lb instead of 36 Nm (38% over-torqued) and of course the aluminum threads were fouled by the steel bolt.

 

Replacing the cylinder and sleeve are just not an option that I'll entertain so I have come up with 2 options:

 

1) Time Sert 1912 kit - http://goo.gl/av2aGg

    - Expensive, but not as expensive as replacing the cylinder and sleeve

    - Very strong, permanent repair

    - Solid steel bushing rather than flexible wire like Helicoil

 

2) Helicoil 5546-9 kit - http://goo.gl/kCeDAW

    - 1/3 the cost of the Time Sert kit

    - Never used them before, but this is a relatively low torque application so maybe the Time Sert is overkill

    - Seem to be a more widely used repair method by people for thread repairs

 

I welcome other ideas from others with a similar experience.

 

Bueller... Bueller...

Share this post


Link to post
Share on other sites

I had that kind of problem on ttr250, the previous owner overtorqued half the bolts that held a cylinder and the head, there was oil everywhere, when I stoped there was an oil stain in that place, it ate more oil than a 2stroke, I bought it fairly cheap and he said it only needed a new gasket  :bonk:

I gave the whole engine to machine shop. Not all of the threads could be restored, most of them had to be increased in size.. well, at least it cost less than a used head

Share this post


Link to post
Share on other sites

I would get a timesert fix it and go on with life

Share this post


Link to post
Share on other sites

Don't mean to take up for anyone, but over time, especially with heat and cool, aluminum will get brittle. I call it rotten! As I do some aluminum welding from time to time. I have also worked on jap motorcycle for the past 45 years. Guess I gave away how old I am :) but back to the question! The timesert is best, but I have did many repair with helicoil! Never had one fail yet in aluminum! They are actually stronger than the orignal threads! Just be careful, use good bits, and drill straight! Cause you can't undrill a hole:) and I would probably give the others a real close look while I was doing the job. Chances are there may be others!

Hope this helps!

Share this post


Link to post
Share on other sites

I appreciate the replies everyone. After sleeping on it I think that Helicoil will be the best bet for this application. The Time Sert only adds thread the length of the bushing which starts at the top of the hole and since the hardware threads are primarily at the bottom half of the bore the Helicoil will be a more suitable repair. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×