J b weld Head Bolts

Helicoil is basically spring steel. You install it in a slightly larger hole. The slightly larger hole you then cut treads into for the helicoil. You put red lock tight into the threads on this hole only. There is a tool that hooks onto the helicoil that gently grabs it to thread it into the prethreaded hole. Now viola you have a hole threaded with spring steel that is your original fastener size. Note this section is not at all where red lock tight goes. Although blue lock tight which is the serviceable grade would be fine here for our application.

I actually put red lock tight in holes at the engine block where the cylinder head studs go. As I am competent not to strip mine out doing something wrong. and I will have no need to take them out of the block ever any way.

‪helicoil‬‏ - YouTube

Exactly my point. Rohmell knows what time it is! It's the aluminium itself. Now you drill out go bigger and what does that leave you? Less metal as a mating surface. And so on and so on and so on. Blah. Blah. Blah.
Think of these motors like a Klenex. After your done with it you throw it away.
After the first time you get your kit, motor, whatever. And you don't do everything you want to do to it then. Then forget about it. Do it to the next one. Cause if you go tearing this junk a part. You'll get it back together but it'll break. Something WILL break! Put it together ONE time. Good. Cause after it starts to bio-degrade you'll find yourself always fiddling with it.
P.S. I ride my bike through some of the most crime ridden neighbourhoods in all of L.A. everyday to work and back. There is no option for me. I have to build em bullet proof. It's like 25 miles round trip.
I'm just curious how much seat time these people that have all this advice to give ride?
Flik One!

Chrisflik said:

Exactly my point. Rohmell knows what time it is! It's the aluminium itself. Now you drill out go bigger and what does that leave you? Less metal as a mating surface. And so on and so on and so on. Blah. Blah. Blah.
Think of these motors like a Klenex. After your done with it you throw it away.
After the first time you get your kit, motor, whatever. And you don't do everything you want to do to it then. Then forget about it. Do it to the next one. Cause if you go tearing this junk a part. You'll get it back together but it'll break. Something WILL break! Put it together ONE time. Good. Cause after it starts to bio-degrade you'll find yourself always fiddling with it.
P.S. I ride my bike through some of the most crime ridden neighbourhoods in all of L.A. everyday to work and back. There is no option for me. I have to build em bullet proof. It's like 25 miles round trip.
I'm just curious how much seat time these people that have all this advice to give ride?
Flik One!

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That paperclip idea just might work in a pinch. With a mutha load of red lock tight!!! Depends how stripped things are. I like it.. Not my cup of tea if I can help it... Pretty Kewl out of the box thinking Some of us have road more than you might think?


If a guy just examines these ''hobby'' engines more closely I think all this is preventable. Some of these motors don't get threaded right from the sweat shop.

The acorn nuts sometimes bottom out before things get snug at the cylinder head too.

Some of these motors did not get threaded deep enough to support the cylinder studs properly at the engine block?

Some of these installs with a unsupported rattling muffler does not help things ether. I mean the muffler is where the noise is. I have looked at a stock muffler before and found with the clutch disengaged..... and stand next to the bike revving it,....... that muffler has a pretty large ''oscillation vibration'' to it!

Other folks have reported that when putting their foot temporarily against the muffler while riding that vibration in their bike went away.

I also suspect that rattling mufflers are the chief cause of folks having to periodically need to re-torque a loosened cylinder head. I like to use these at my cylinder head dressed with a light coat of head gasket capable compound I use this. Google




At the muffler gasket I typically use a aluminum gasket [Has these: http://www.sickbikeparts.com/ ] with Copper Koat or the high heat Permatex copper gasket maker. I find the Aluminum gasket matches the expansion and contraction rate of the jug and exhaust flange nicely. I have no leaks this way!


My biggest personal peeve is stuff rattling!!

Of coarse if one puts their foot on a hot muffler I am sure they understand they stand a chance of melting their shoe a little?

Check it out Goat Herder. I know what a Helicoil is. You don't have to cut a paste the directions on how to use the tool. If you were to use the application to lets say a steel block. Sure, use a helicoil. But this is totally the wrong time and place for it. It's over kill. Yes "your right" you can totally helicoil it and it maybe will work for a period of time. But after you do that. Something else will break that's irreparable.

Both of these posts are absolutely correct to a degree but have some technical inaccuracies that I would like to point out:

rohmell said:

If the threads stripped due to soft aluminum using a regular bolt, why would anyone think that the HeliCoils will hold any better in the same soft aluminum?

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First off most of the time Rohmell I don't think we have thread failure on the China girls because the base being metal is aluminum. It is usually due to improper mounting techniques, over torqueing and aluminum metal fatigue.

• Improper Mounting techniques:
  The engine must be mounted securely to avoid thread failure from vibration.
• Over Torqueing:
  Some people think the tighter the better use a torque wrench. Acorn nuts on cylinder studs are the worst offender if they are bottomed out you will transfer the torque to the crankcase holes and strip them out.
• Metal Fatigue:
  Even when properly torqued over a period of time threads will fail because the torque is being carried on the pitch of the threads only and friction of torqueing and the elasticity of cast aluminum they will fail.

Realistically due to the material that Helicoils are made of and it being more elastic and the fact of them being spreading out the load of the torque more efficiently simply due to their size they will last longer and be far stronger if properly installed.

Goat Herder said:

Helicoil is basically spring steel. You install it in a slightly larger hole. The slightly larger hole you then cut treads into for the helicoil. You put red lock tight into the threads on this hole only. There is a tool that hooks onto the helicoil that gently grabs it to thread it into the prethreaded hole. Now viola you have a hole threaded with spring steel that is your original fastener size. Note this section is not at all where red lock tight goes. Although blue lock tight which is the serviceable grade would be fine here for our application.

I actually put red lock tight in holes at the engine block where the cylinder head studs go. As I am competent not to strip mine out doing something wrong. and I will have no need to take them out of the block ever any way.

‪helicoil‬‏ - YouTube

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When I had my shop I was a Sthil, Echo, Target, Honda, Tecumseh and Briggs dealer and repair station. And had almost a daily need for HeliCoils. One of the things I kept when I sold the business was my HeliCoil rack that has virtually all sizes of coils in 3 different lengths, drill and tap, installation tool and tang breaker for each size in both metric and SAE all in individual trays. Out of 6 techs I had only 2 I though competent that I would allow access to the racks because they understood when a coil would make a good repair and when it wouldn't, how to do the repair right and make sure all of the tools got back in each tray.

A couple thing to consider when using a coil to repair threads (especially on these engines) is if you have enough wall surface (or meat) to drill and tap into as well as Depth to insure a good repair. For motor mounts both front and rear you defiantly have enough depth but you will might be pushing it in sidewall surface on one axis after dri9lling and tapping, For cylinder studs I am not sure on side wall surface area but you might get in trouble on depth.

As I said I have not considered HeliCoil repairs for China Girls in favor of either filling it with a TIG or Alumi-Welding and then locating the hole with a transfer punch and drilling and tapping a new hole.

Most places that sell HeliCoil brand coils made by Emhart Teknologies sell coils with the proper drill and tap for that coil I suggest not using cheap taps from kits as the pitch can be slightly different and that you use that specific drill recommended for that tap or you will get a sloppy repair. Also using proper tapping techniques such as not trying to hog through the casting because it is soft aluminum and instead turning the tap only 1/4 turn clockwise then an 1/8th back to break the chip will give a good thread. Knowing the difference between a through tap and a bottom tap helps and use TapMatic thread cutting fluid and not oil.

Below is a PDF that has everything you need to know about HeliCoils and how to properly install them:

HeliCoil Specifications

Thank you MarkSumpter for that very informative explanation on the correct use and application of a Helicoil. Now that's what I'm talking about.
Listen to Mark! He sounds like he has knowledge and know how.

I can do pretty much anything I want I have a Aluminum welder now too as of last fall. It cuts it pretty close but I did do one of these. I have also done the rear left motor mount side successfully. Twice. Once for me I wanted it beifyer. Both for acquaintances that did not have a prob. Problem is no body has the tools or hands on experience. Your right I would not let just anybody do a helicoil. I don't personally recommend anything I have not tried.

The op is long gone and seams to have shown no interest. He may possess talents we don't know? I don't really like these HT's all that much anyway. But I can make them run peachy!

Thanks Chris for the compliment but there are people here that have a lot more experience with these engines than I do but after 30+ years as a small engine guy I have learned a thing or 2...

Goat you are right and I am sure your repairs came out fine.

What most people dont understand is it is not just the type of material that will determine the strength of a thread it is also the fact that it is the pitch of the thread that carries the load so a higher thread count (depth of thread) and surface area (diameter of the thread) that work with the type material and its elasticity to make a strong thread joint that resists stripping out for what ever reason.

Anyway a properly installed HeliCoil is a godsend and a bad install is a nightmare. If you don't know what you are doing take it to someone who does and if you have the opportunity watch and learn I really never minded showing people how to do things.

Unfortunately I lost some stuff in that last post I will have to proof read when I do these long ramblings LOL...

Goat Herder said:

The op is long gone and seams to have shown no interest. He may possess talents we don't know? I don't really like these HT's all that much anyway. But I can make them run peachy!

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Or broke his neck from his paste job on the motor mount... Overall it is a good thread though with good questions and answers from all concerned.

I have my China Girl that hits 38 mph and has well over 2000 miles and still going strong but I have always liked the challenge that 2 stroker give LOL...

Like I had said in another thread my ducati's motor has helicoils in every tapped hole in the engine from the factory. i've never seen that in a jap bike before. pretty interesting.

I think it was this thread Taco... If they HeliCoiled it they probably had the casting molds made to maximize the coil strength by having the proper depth and sidewall clearances, kind different than trying to properly coil a casting not made for them. Probably can be done but you might end up with something less mechanically sound than just the aluminum threads are.

MarkSumpter said:

I think it was this thread Taco... If they HeliCoiled it they probably had the casting molds made to maximize the coil strength by having the proper depth and sidewall clearances, kind different than trying to properly coil a casting not made for them. Probably can be done but you might end up with something less mechanically sound than just the aluminum threads are.

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Properly done helicolis are stronger than aluminum threads. Click here.. on the google insignia I linked. Ever header in the subject listing says stronger than the original. Google

They were invented for light weight aluminum air craft motors By N.A.S.A. used even in our space shuttle!

‪helicoil‬‏ - YouTube


The fasteners on these engines are only originally rated for about 13 foot-pounds.

I agree completely that HeliCoils are stronger than aluminum but only if they have the proper wall clear clearance to install them as well as proper depth for the end threads and tang to be removed. There are numerous other factors that add to strength but in these engines they would be 2 of the most important and not understanding them is a recipe for threads could well be less durable than what you currently have. Specific castings are made meatiers in engines that use coils to give higher torque specs. If you have too thin of a side wall in any axis or improper depth clearance resulting in trimming of the coil it is not optimized for strength at the mold shop like these engines aren't. Tacos Ducati was most assuredly molded by the specs in the PDF Below.

Again look through it. It gives all of the clearances pitches and specifications required to properly install a coil and maximize stress loads.
HeliCoil Specification PDF

Just pulling your leg a little Mark you are totally right.

mark, I'm sure they did add it in when they engineered it agreed toatally. Also the wall thickness is thin enough with the factory threade holes esp on the motor mounts on theese ht's it can be done though. how strong will it be depends on all the factors mentioned above in previous posts.