Stripped exhaust threads

[FreeWheeler]

I came here for the straight dope that Norm dishes out, or that someone who knows the straight dope on these far east abominations for 2 stroke engines. I mounted the thing and then tried to install the exhaust pipe and the threads coming out of the engine stripped and wouldnt accept the nut. I thought ok, I'll remove that threaded rod and insert an intake bolt. That stripped the threads inside the engine side. It runs, but the exhaust is only tight on one side and I know it will beocme a problem.


What kind of kit do I need to rethread the exhaust? I thought about jamming some JB Weld down the hole, but came to my senses and figured there must be a proper way to fix this.

 

[biken stins]

JB weld might come out after some time.
Tap it out to 1/4". You can get the threaded rod reasonable and will have it around as the others strip out.

 

[FreeWheeler]

Does Ace sell the taps and the rods? Do I need to spend alot on the tap kit?

 

[biken stins]

ace and most hardware stores have them. sears and k mart. Price varies . Use them right and they will last a long time.

 

[retromike3]

What I did for my old engine was installed a Heli-coil. Its a spring that treads into a larger hole that you drill and tap. Gives you a "new" set of threads. I have used them on several different jobs and they don't seem to fail.

Mike

 

[Bikeguy Joe]

Taps are in the 5 dollar range then just use a grade 5 bolt to mount the exhaust, 15 cents

 

[FreeWheeler]

Thanks!

I'll get a tap and some threaded rods for next time. ....But wait a second... I gave it one more try with the threaded rod with the stripped end. I put the nut on from the clean end and grabbed the boogered end with pliers and very slowly screwed it in. It worked. There's maybe 1/4 inch of rod sticking out from the tightened nut. I guess the threads werent stripped and maybe the intake bolt was just hitting bottom?

 

[retromike3]

I would think about getting some stronger rod than the cheep stuff they ship with the kits Sick Bike Parts sell a full set of hardware that is stronger for a good price. I am ordering that kit for my new motor.

MIke

 

[FreeWheeler]

I would think about getting some stronger rod than the cheep stuff they ship with the kits Sick Bike Parts sell a full set of hardware that is stronger for a good price. I am ordering that kit for my new motor.

MIke

I got lucky this time and was able to make what I had work, but I hear you. How much does one of those heli-coil kits cost and where can I find them?

 

[Al.Fisherman]

I'd be surprised if it holds, start thinking of what you will do when it cuts loose, as I'm sure it will. Can you torque the nut to 50 inch pounds?


http://s982.photobucket.com/albums/ae309/Ron-Becker/Repair exhaust stud holes/

 

[Goat Herder]

Well if you know an Ace welder fill the hole back in and redo it. Better yet put more material around the flange so's to seal up exhaust leaks better.

I got a project dead in the water right now I plan to build up the flange on the jug. I have a wire feed Lincoln with a spool gun.

 

[retromike3]

I got a Heli-coil kit for about 26 bucks at my local ACE hardware. I think its worth the price.

mike

 

[FreeWheeler]

I didnt check it with a torque wrench, but it is snug as I can get with a dinky little 10mm wrench. I do have 2 large torque wrenches. The cheapy has a spring needle gauge that you read by eye, pull until the gauge reads what you need. The other is a more expensive type that I havent quite figured out, you loosen the handle and then tighten it where it reads desired torque and then it clicks once torque is reached. What I cant figure is exactly how to set it. I wouldnt want to be off by 10 ft/lbs when I only need 10.

I digress some. I probably got the nut on with atleast 4-5 ft/lbs, maybe more but less than 10.

 

[retromike3]

What I did on my last install was to use two nuts and bind one against the other I did not torc them down too tight. They did hold for a wile but I had other problems.

Mike

 

[Goat Herder]

Your studs should always be bottomed out tight to the block. Why this takes the stress away from the threads. It will pull wrong on the threads other wise.

Used to run into the same nut and stud combo when wrenching on cars. A lot of techs would drive the stud in tight by the nut. [Lazy cheating when commercially wrenching] While I never saw a stud strip out at the engine[rare] it could lead to an exhaust leak later on those automotive headers.

 

[Al.Fisherman]

I didnt check it with a torque wrench, but it is snug as I can get with a dinky little 10mm wrench. I do have 2 large torque wrenches. The cheapy has a spring needle gauge that you read by eye, pull until the gauge reads what you need. The other is a more expensive type that I havent quite figured out, you loosen the handle and then tighten it where it reads desired torque and then it clicks once torque is reached. What I cant figure is exactly how to set it. I wouldnt want to be off by 10 ft/lbs when I only need 10.

I digress some. I probably got the nut on with atleast 4-5 ft/lbs, maybe more but less than 10.

In this cast aluminum 6mm is torqued to between 50 and 60 INCH pounds and 8mm to between 150 and 200 INCH pounds.

I NEVER tighten a stud so tight that it bottoms out. What I do is put a drop or two of lock tite on the stud, tighten till it bottoms out and back it off about 1/4-1/2 turn. Let sit to dry a few minutes or more. This will give room for the aluminum expansion ( Automobile aluminum engines are made with better materials and don't get as hot). I don't know how much expansion there is but I know there is more with the aluminum then the steel studs.

I can fill stripped holes here at home, but to take it to someone that charges is just NOT cost effective.

 

[Goat Herder]

In this cast aluminum 6mm is torqued to between 50 and 60 INCH pounds and 8mm to between 150 and 200 INCH pounds.

I NEVER tighten a stud so tight that it bottoms out. What I do is put a drop or two of lock tite on the stud, tighten till it bottoms out and back it off about 1/4-1/2 turn. Let sit to dry a few minutes or more. This will give room for the aluminum expansion ( Automobile aluminum engines are made with better materials and don't get as hot). I don't know how much expansion there is but I know there is more with the aluminum then the steel studs.

I can fill stripped holes here at home, but to take it to someone that charges is just NOT cost effective.

From an engineering point that is wrong even with lock tight you have now left something loose on top of a rattling engine. Let alone the unnecessary stress on the threads. That which rattles destroys itself. I have buddy's that use plain ol cap bolts and it works fine.


Aluminum engines if you dig into an All Data, Mitchel On Demand computer manual for auto repair. Explains the studs as I have mentioned. It is not suggested to turn them back anywhere ever......

The way I mentioned this is practically in there so called sticky's
Look where they go into generic bolts sizes and there torque specs.

 

[Goat Herder]

Exhaust Gasket Replacement FAQ

HollowPoint RC Exhaust Stud kit review. - R/C Tech Forums

The M.B.'s best friend is blue lock tight.

And throw the paper gasket in the trash! Use a copper or aluminum gasket there. They expand and contract with the heat staying sealed. SBP has them http://www.sickbikeparts.com/catalog/images/exgasket.JPG

No where on the internet is it suggested to leave such a stud fastener backed off. I dare you to find it........

 

[FreeWheeler]

The motor isnt broken in yet, I dont think. I'm guessing about 25 miles since my test loop is about 1.25 miles. What I want to do first is replace the stud with the same specs and before I do that use a piece of wire to find the depth. This way I know where bottom should be. If this fails and something says it shouldnt, then I will weigh every suggestion. I think the intake bolt didnt work because it hit bottom before it got tight and I thought that meant it was stripped. Current bodge is holding tight, but I know the nut end of the stud is fouled up.

 

[Al.Fisherman]

The motor isnt broken in yet, I dont think. I'm guessing about 25 miles since my test loop is about 1.25 miles. What I want to do first is replace the stud with the same specs and before I do that use a piece of wire to find the depth. This way I know where bottom should be. If this fails and something says it shouldnt, then I will weigh every suggestion. I think the intake bolt didnt work because it hit bottom before it got tight and I thought that meant it was stripped. Current bodge is holding tight, but I know the nut end of the stud is fouled up.

If a stud doesn't tighten up there are only three things that come into play (assuming you are using the correct size stud) and that is the stud is not bottomed out, or the stud or stud hole is stripped. When putting this cheap junk together, unless you chase the threads before instillation, I recommend measuring the depth of the hole, and compare with the remaining length of the stud sticking out. This way you will know if the stud bottomed out or just got tight. Personally I torque ALL my studs (6mm 50 inch pounds) and (8mm to 150 inch pounds) then I back them off 1/4 to 1/2 turn. As far as backing off, some people say NO...it's my personal preference. I have never had a stud break, stretch (I use grade 8.8) or strip out. Do it right the first time.