Topic: Stripped Header Stud

[maconnoise]

When I replaced the headers on my 78 CB750k a few days ago I discovered that a PO had stripped the threading out of one of the stud holes in the cylinder head. Right now the stud barely stays put and just rotates if you put more than a few pounds of torque on the header bolt. I looked into the hole and nearly all of the threads are gone.

What are the possible fixes for this? I am no master mechanic and I don't plan on pulling the engine any time soon so getting a machine shop involved is a worst case scenario at this point. Not particularly jazzed about drilling and tapping either.

I guess JB Weld is a bad idea 

[calj737]

Heli-coil or Threadsert is your best bet. These will be installed in a larger hole, but provide a standard sized hole for the exhaust studs to be screwed into.

Stripped holes is not uncommon when ham-fisted owners over-torque steel bolts into aluminum casings. These particular studs need little torque at all, should be installed with thread sealant, and the installation of the exhaust and gaskets with nuts is all that's required to keep things sealed up.

[madmtnmotors]

I guess JB Weld is a bad idea 

Very bad. 

Helicoils are fairly straightforward, the hardest part is keeping it square and true since the header studs are at odd angles.

[maconnoise]

Yeah looks like Helicoils are going to be the best bet. I'm just never excited to go drilling holes into my engine. Call me crazy.

Thanks for the info. This is my first real project bike and I am still a bit unsure of my abilities. It's been a long time since I spent any real time in a shop.

[flybox1]

find someone who can do it for you.
it needs to be done right, the first time.  search the SERVICES section of CL for mobile auto repair.

IIWM, i'd leave the opposing stud in, and slide the exhaust collar on it to be used as a drill guide, or to familiarize myself with the angle the stud needs to be placed.

[madmtnmotors]

IIWM, i'd leave the opposing stud in, and slide the exhaust collar on it to be used as a drill guide, or to familiarize myself with the angle the stud needs to be placed.

That is a heck of an idea, I had not considered that  ! I have yet to repair the threads for an exhaust stud, but it's only a matter of time  . Rest assured I will use the collar as a guide when that time comes. 

[Flyin900]

If you have the hole there already then I would use only hand tools and nothing power operated to hand tap a larger thread for the insert.

Never been a fan of Heli Coils and prefer Time Serts for a much better and stronger repair, yet the tools/taps are not cheap to buy for a one time repair. There are also Big Serts if the hole is really messed up.

[MRieck]

I guess JB Weld is a bad idea 

Very bad. 

Helicoils are fairly straightforward, the hardest part is keeping it square and true since the header studs are at odd angles.

Agreed

[PeWe]

Make a thick guide to ensure correct angle when doing the threads for helicoil. It can be fastened with the ok bolt.
It's very easy to aim the helicoil thread tap wrong and stud will not fit correctly.

[Davidov]

If you have the hole there already then I would use only hand tools and nothing power operated to hand tap a larger thread for the insert.

Yes. You should get one of those tap handles  for the drill bit and drill out the hole by hand. It's just aluminum.

[Dino]

I like E-Z Lok inserts best. They use standard thread taps and drill sizes and they install with a flat blade screw driver. Each insert is coated with thread lock. I love these and swear by them. I've installed dozens over the years. http://www.ezlok.com/InsertsMetal/carbonSteel.html

[750cafe]

These might help...












Eric