Stripped exhaust studs.


Stripped exhaust studs.

Postby steve murdoch icoa #5322 » Tue May 18, 2010 7:53 am

In changing the pipes on my '81 i found i have 2 stripped exhaust stud holes.
Are the studs themselves 6mm at both ends?
If using a Heli-Coil insert should i use some Loc-Tite when re-inserting the stud?
Does it make any sense to re-tap the head to 8mm instead and going with the larger stud. Is this possible?
Thanks for any info, gents.
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Re: Stripped exhaust studs.

Postby EMS » Tue May 18, 2010 8:20 am

I had the same problem on my '79, Steve and I used Heli Coil and Loctite. The studs are 6mm on both sides. My concern with 8mm studs would be, that there is not all that much material in the head around the studs to enlarge it to 8mm. You would also have to drill out the header flanges. The holes are only about 7mm.
You could probably get studs that are 8mm in the head and 6mm for the flanges.
I would also be concerned drilling and tapping new threads with the head on the engine. Very poor angle to do a good job :roll:
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Re: Stripped exhaust studs.

Postby ericfreeman » Tue May 18, 2010 10:38 am

I had to helicoil about 4 of the studs in my '79. Much better than trying to drill for larger size. Biggest problem is keeping the drill bit lined up properly for a straight hole. I had my front end off at the time so there was plenty of room to get to the front of the motor. Best of luck.

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Re: Stripped exhaust studs.

Postby alimey4u2 » Tue May 18, 2010 4:02 pm

Using an old/junk exhaust flange as a lead in guide for the drill bit may help you get the angle right....As said before... Good luck.
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Re: Stripped exhaust studs.

Postby steve murdoch icoa #5322 » Tue May 18, 2010 8:04 pm

Thanks for the info guys. The old flange as a guide is a good tip, Larry.
I will report back with the results...fingers crossed.
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Re: Stripped exhaust studs.

Postby steve murdoch icoa #5322 » Mon May 24, 2010 2:23 pm

Both exhaust stud holes successfully repaired. Heli-coil, Loctite and new 6mx55m studs. According to the part numbers the early studs were 50mm in length.
I know this is a small job in the grand scheme of the life of a CBX but it had me worried.
Thanks for the info.
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Re: Stripped exhaust studs.

Postby EMS » Mon May 24, 2010 3:50 pm

Great going, Steve!
Studs changed for 1980 to 6x55 8)
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