Help! Helicoil disaster

[jsouth]

Last fall, I misread the manual and overtorqued the bottom cap nuts on the head flange. I finally got the courage to attempt the repair today. I successfully removed the head. But when I attempted to helicoil the damaged threads on the jug, I messed both of them up and now the helicoils are chewing bolts.

Rather than attempt to repair the damaged threads with time-serts ($$$) or some other method, I'm considering just replacing the jug. My engine has about 107k miles on it. What are the chances of a successful outcome if I purchase a used jug and transplant it without changing my piston or rings?

I feel sick....

 

[ksdcr]

IIWM, I’d do the time serts. They have a reputation for being very strong.

 

[robsryder]

One of the first times that I tried to do a heli-coil repair I made a mess of it. This was on the final drive of an airhead; one of the threads holding a stud got stripped and I messed up the heli-coil insertion (also didn't drill in perfectly straight). I took the final drive to a local machine shop and had them put a keen-sert in (they had a large enough jig or vice to hold the final drive in the proper position). This repair worked and was much less expensive than replacing the final drive.

A keen-sert is similar to the time-sert in that a bushing is used, but the keen-sert has some pins that are driven into position after insertion to firmly hold the insert.

https://www.bossard.com/us-en/product-solutions/brands/threaded-inserts/keenserts/

http://www.repairengineering.com/keensert.html

https://www.carrlane.com/product/threaded-inserts

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[jsouth]

One of the reasons I don't want to mess with any other insert is that it is difficult to get a tap in that location. With the head off, the plastic chain rails and the chain with sprocket ziptied are in the way of the tap handle.

Does anyone have input about swapping the jug? I have read that the Nikasil liners are pretty bulletproof and don't wear much at all. That would seem to make this a do-able repair. Used jugs are readily available and not expensive.

 

[pglaves]

One of the reasons I don't want to mess with any other insert is that it is difficult to get a tap in that location. With the head off, the plastic chain rails and the chain with sprocket ziptied are in the way of the tap handle.

I understand that frustration. As a result I bought a long, ratcheting tap handle. See only as an example:

https://www.amazon.com/Hanson-21212-Extended-Length-Ratcheting/dp/B000QJ8VQU

 

[jsouth]

I understand that frustration. As a result I bought a long, ratcheting tap handle. See only as an example:

https://www.amazon.com/Hanson-21212-Extended-Length-Ratcheting/dp/B000QJ8VQU

Paul, some of the reviews of that extended tap handle and another like it show that some users could not chuck the tap in the tool straight. Is that probably user error or have you seen that problem?

Also, I'm reading into your response that you don't think the jug replacement is a good idea - is that an accurate assumption?

 

[Omega Man]

Only bought a few specific but have made a few including yesterday for a defective product-

https://biggatortools.blog/what-is-a-tap-guide/

Achieving 90* to the piece being tapped- or threaded, is usually critical.

OM

 

[PoorUB]

Last fall, I misread the manual and overtorqued the bottom cap nuts on the head flange. I finally got the courage to attempt the repair today. I successfully removed the head. But when I attempted to helicoil the damaged threads on the jug, I messed both of them up and now the helicoils are chewing bolts.

Rather than attempt to repair the damaged threads with time-serts ($$$) or some other method, I'm considering just replacing the jug. My engine has about 107k miles on it. What are the chances of a successful outcome if I purchase a used jug and transplant it without changing my piston or rings?

I feel sick....

What do you have to loose if you try repair the threads with a different style of insert? Screw it up completely? I would buy a tap handle extension, or try some other trick to do the job. Often a squared drive on a tap will fit close enough in a twelve point socket to do the job.

Trying an Time Sert will be better than pulling a cylinder, at least IMO.

 

[pglaves]

I am confused. What threads, exactly, are messed up? Head/cylinder studs? Which threads?

 

[jsouth]

I am confused. What threads, exactly, are messed up? Head/cylinder studs? Which threads?

The two M6 x 1.0 bolts on the very bottom of the head flange. Last fall, I had a leak on a trip (now I believe it was the valve cover gasket, which I have never replaced). On my return, I got the factory manual and read the torque spec for different bolts, and stripped the threads.

 

[jsouth]

What do you have to loose if you try repair the threads with a different style of insert? Screw it up completely? I would buy a tap handle extension, or try some other trick to do the job. Often a squared drive on a tap will fit close enough in a twelve point socket to do the job.

Trying an Time Sert will be better than pulling a cylinder, at least IMO.

That was, ultimately, my conclusion. I have ordered an extension tap handle and the time-sert kit. I'll have it all by Saturday but won't get to work on it until Tuesday or Wednesday of next week.

Good tip about the 12-pt socket! Thanks.

 

[jsouth]

Follow-up:

The Time-Serts arrived early and I had time Saturday to do the repair. The bike started easily and runs properly.

Time-Sert, although expensive, is a slick system. The tap for the M6 x 1 Time-Sert is identical to the one for the same-sized helicoil. I was previously able to get the damaged helicoil out, and I cleaned the threads with the Time-Sert tap. Then I drilled the counterbore for the insert lip, blew out the hole, and installed the insert. Paul's advice on the extension tap handle worked perfectly. The repair took less than five minutes from start to finish. I have no idea why I could not get a successful helicoil repair in that hole, but the time-sert worked.

Reassembly went well, and all fasteners took the required torque.

Thanks to the experts on the forum for their advice.

 

[Omega Man]

Follow-up:

The Time-Serts arrived early and I had time Saturday to do the repair. The bike started easily and runs properly.

Time-Sert, although expensive, is a slick system. The tap for the M6 x 1 Time-Sert is identical to the one for the same-sized helicoil. I was previously able to get the damaged helicoil out, and I cleaned the threads with the Time-Sert tap. Then I drilled the counterbore for the insert lip, blew out the hole, and installed the insert. Paul's advice on the extension tap handle worked perfectly. The repair took less than five minutes from start to finish. I have no idea why I could not get a successful helicoil repair in that hole, but the time-sert worked.

Reassembly went well, and all fasteners took the required torque.

Thanks to the experts on the forum for their advice.

Nice!
Always good to hear how you made out.
OM

 

[mikegalbicka]

Good job. Perseverance paid off.