Author Topic: Fixing stripped bolt hole on header pipe (Read 8063 times)

rab1dwolf · « **on:** July 30, 2006, 07:15:32 PM »

I pulled my header pipes on my exhaust off today to see why I was getting leakage at the engine. When I removed the rounded nut that holds it on the whole bolt came out of the engine and had the threads from the hole still attached to the bolt. I need to fix this since I cant get it down tight enought to seal the pipe to the engine and am getting serious blow by.

What are my options for fixing this? I have read references to helicoil to fix similar issues but was wonder if I could just jb weld the bolt back in or replace with a larger bolt since this thing isnt supposed to come out from what I can tell.

It seems everytime I work on one part of the bike another part has an issue.

fourplay · « **Reply #1 on:** July 30, 2006, 07:34:22 PM »

Hey, I was just telling my wife today that my current 77' CB750K is wearing me out with all the little nick nack stuf that is broke or missing.

I really would think the proper repair would be to helicoil the hole so you could screw the stud back in. However, I am a big believer in JB Weld.

My Dad threw a rod in his 18 wheeler years ago. It made a hole you could put your hand in easy. The cast part of the block that broke off was in one piece, so my dad repared the one clylinder (common in big diesels) and put JB Weld on the block and the broken piece. I told him he was crazy but it held for two years with no leakage or problems. That really sold me on that stuff.

Anyway, you could try it. I know I would if that is what it would take to fix it for now. You can do a proper repair if you ever take the engine down for a rebuild.

rabidelf · « **Reply #2 on:** July 30, 2006, 08:57:07 PM »

Fixing it with a helicoil or a timesert is not much more expensive/difficult than JB weld in the long run. The investment in the tool is well worth it. You will need to do it again someday, trust me.

rab1dwolf · « **Reply #3 on:** July 30, 2006, 09:20:18 PM »

is jb weld ok to use on something that gets as hot as my engine?

I quickly checked the helicoil prices using a google search and it came back with metric being about 50 bucks....

my friend has jbweld that i can steal so....price wise im leaning towards the jbweld

eurban · « **Reply #4 on:** July 31, 2006, 05:11:57 AM »

I would seriously doubt that gluing your exhaust stud back in place will provide a lasting solution for holding the header tight to the exhaust port. Try it if you like but you will probably need a helicoil or other thread insert to actually fix the problem. . . . .

oldbiker · « **Reply #5 on:** July 31, 2006, 05:41:00 AM »

There is one other possibility. Tap the hole that is left 10mm and get anyone with a lathe to turn a new stud 10mm one end and 8mm the other. this stepped stud will let you assemble your header OK. This will cost almost nothing but you cant go back once you have done it.

dusterdude · « **Reply #6 on:** July 31, 2006, 05:49:09 AM »

timesert is the #$%*

Bodi · « **Reply #7 on:** July 31, 2006, 06:10:35 AM »

I would use a timesert or keensert, ther's a lot of pull on that stud and helicoils have failed on me pulling out the new larger threads - because they are still the same fine pitch maybe? A timesert is pretty much forever and the outer threads are a longer pitch more suited to the larger diameter.

crazypj · « **Reply #8 on:** July 31, 2006, 06:35:40 AM »

I my experience JB weld wont work on an exhaust port but will look exactly what it is, a total bodge by some one who either doesnt know or doesnt care what they are doing. There is only just enough metal to tap to 8mm I belieive. Honda used stepped studs on the DOHC later model CB750 (with hydraulic tappets) They are 6mm one end and 8mm the other. If too long , cut down the 6mm part and re-thread. The australian made re-coil kits a\re about $28~35.00, very similar to helicoils but you dont ge a 'pretty' insertion tool. 6 mm inset has a 7mm outside diameter, so if you mess it up you can always go to the 6mm~8mm stud.
PJ

ElCheapo · « **Reply #9 on:** July 31, 2006, 06:39:31 AM »

You just tap it and get a step stud. Dont complicate this, it should be easy. I had to do a similar repair on a Harley EVO head that had the exhaust stud drilled out and then the guy poked his drill through exhaust port.

Easy fix if you know how. But a simple tap and a step stud and you should have it fixed in a few minutes.

rab1dwolf · « **Reply #10 on:** July 31, 2006, 10:52:17 AM »

so how do i go about retapping the hole and where would i find a step stud?

ElCheapo · « **Reply #11 on:** July 31, 2006, 10:57:35 AM »

Step studs are availalable at anyautomotive parts house. Look on your tap guide and it should tell you which tap to use and which drill bit to use to clean up the hole. It does not have to be exact. If the hole is a little small it is not a big deal. When you run the tap in it will remove the excess.

gizmo · « **Reply #12 on:** July 31, 2006, 12:19:17 PM »

you could do an old trick i had shown to me get an 8mm bolt drill and tap the centre to 6mm cut the excess off so you basically have an 8mm slug apply threadlock screw in and screw back in the 6mm stud for the exhaust regards tony

ElCheapo · « **Reply #13 on:** July 31, 2006, 03:35:24 PM »

Just cut the darn threads, Funny how people complicate things. It is not rocket science. Just tap the stupid hole and put a stud in it. This repair should take about 10 minutes grand total.

dare was a trick dis ear guy shown me. dag gum slick to ahuh....................... really this thread has worn itself out.

rab1dwolf · « **Reply #14 on:** July 31, 2006, 09:19:26 PM »

gotcha. never tapped a whole before. my friends got a metric kit (he thinks) so we'll give it a shot. sounds easy enough:)

fourplay · « **Reply #15 on:** August 01, 2006, 01:26:49 AM »

I told you the JB Weld would work because I figured you had never tapped a hole before. If it didn't work you could drill that stuff out when you tried to drill and tap.

To tell the truth, it really is not hard to do. Just like anything, the first time is difficult but it is easier than you think.

I have done all of the above. I have had good results with each, but would recommend the proper procedure. An exhaust stud takes a lot of heat and you can ruin a head if you do too much drilling over and over.

Fix it right and if you are uncomfortable with it, find someone to do for you.

rab1dwolf · « **Reply #16 on:** August 01, 2006, 11:18:50 AM »

my buddys going to bring over his kit if he can find and and we'll take a crack at it. I figure I'll do both the holes since I think the other one is fairly shot too. I'll let everyone know how it turns out

gaustin · « **Reply #17 on:** August 04, 2006, 10:26:43 AM »

I had to do this on my k4 and I was very skeptical at first (with my skill, not the kit) since I never tried something like this, but since I had the tap kit I decided to steady my hand and give it a go... two minutes later the bolt was tightening down like a champ. Amazingly easy with a level hand!

Good luck

rab1dwolf · « **Reply #18 on:** August 20, 2006, 08:28:53 PM »

my threads werent completely shot so I was able to retap it with the same size tap and it worked great.
Fyi if anyone needs a good cheap tap set check with harbour freight I got mine for under $20 and it has a ton of stuff in it.

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Author Topic: Fixing stripped bolt hole on header pipe (Read 8063 times)

fourplay

rabidelf

ElCheapo

ElCheapo

gizmo

ElCheapo

fourplay

gaustin