Stripped Header Bolt

The bolt going into the motor on my exhaust header is stripped and will no longer torque up. Has anyone else run into this problem and found a good solution? Not sure if I've got enough material to use a Helicoil or Timesert. Wondering if I might be better off just tapping it to a slightly larger bolt size (maybe a larger SAE bolt that is very close in size)?

Tapping to a larger size is a last resort. If you think you can tap it larger, then you can Helicoil or Time-Sert it.

I assume you mean the threaded spot on the head, right?

^^^what he said:thumbsup:

Yes, the threaded spot on the head. I'm worried I won't have enough material around that hole to drill it large enough to fit a helicoil. A friend also suggested coating the bolt in JB Weld and screwing it into the head and letting it dry. I'm afraid that when I torque it down though, it will just pull the JB Weld out.

Dont use jb-weld. That stuff should not be used for things like this. You wouldnt be able to torque it to spec with jbweld in there.

Heli-Coil it. The next metric or English sizes are each larger than the cut required to thread the coil.

The Allen bolt in the header joint, IMO, should be torqued up by first seating the header in the head, then lightly tightening the flange so it sits square. Then back off the nut on the stud about one flat (a little more if it's a new header seal), and tighten the Allen to about half its torque spec. The header flange will be tipped slightly off square by this, with the outer side under the nut lifted a little away from the collar on the header. Now tighten the nut to clamp the header. Doing this will stress the steel threads of the stud, rather than the aluminum threads in the head, and it will increase the clamping load on both the stud and the Allen without so much risk of stripping.

Thanks, I'll try a Heli-Coil and tighten according to your suggestion.

I just stripped mine also. My problem was I didn't have a crush washer so I put one in and it made the header stick out an extra 1/4 inch or so I thought nothing of it. When I went to bolt it back up I had the nut too tight on the stud on the other side. When tightening the bolt I pulled probably half the threads out of the head I put a longer bolt in and can tighten it up now with the remaining threads but I'm paranoid it won't hold up. Wondering if I can make it a stud with a nut just like the other side or any advice. I have never used a heli coil but can borrow a set from a co worker and give it a try but I'd rather leave that as a last choice. Thanks Jeff

Ps I do realize this is an old thread but I did search before starting a new one hope someone sees this lol

For anybody reading this thread I'd recommend replacing the bolts with studs before it needs repairing.

I don't know why it would ever be a problem.  The Allen bolt should be run in first to the point where it starts to snug up and the stud side of the header flange is slightly tilted "up" farther than the bolt side.  Then, the nut is tightened down to secure the header, often without disturbing the Allen bolt nay more at all beyond that.  This first assures adequate thread contact, and also reduces the frictional stress on the threads.  A tiny dab of anti-seize on the Allen is also helpful.

I was waiting for you to get on here lol Ya that was my problem I had the nut to tight on the stud side. Never thought about it till I felt the bolt pull out. So should I just run the longer bolt like I have in now, make it a permanent stud and nut or tap it to the next size up and heli coil it. And so I don't have to take my header off to get to my oil filter can I just take the long bolt out and use threaded rod and a nut. You said something about just it making it a bit harder to line up the cover but as long as I keep and eye on it I should be good?? Thanks

You know, I did go with a stud and nut on the upper forward filter cover bolt for a while, but the fact of the matter is that even that was a pain in the ass because it was difficult to get at the nut with a normal wrench.  I modified one to make it easier (I'll add a picture of it later - you'll get a kick out of it), but it was still more trouble than I wanted, and I got tired of the whole thing.  So when I had the engine out recently, I decided that on the way back together I would "modify" the header for clearance. 


Essentially, boiling it down to simple terms, I pounded an elongated dent across the bottom of the header in line with the filter cover bolt, just enough to barely clear, and left it at that. :excuseme: 


As far as the header is concerned, I'm not certain, but I believe that Yamaha got started with the Allen bolt on the inside of the flange because of the forward tilt of the Gen1 engines (400F-early 450's) and clearance issues with the steel frames.  The Gen2 450 ('06-'09) are more vertical, and there may not be any reason not to use a stud there.  If you have a "nut and a half" worth of threads still left in the hole where the Allen belongs, a stud may work for you, as long as you can get the flange over it with the stud in place.

Thanks grayracer iv also got into situations where iv had to take a wrench to the bench grinder. As for the filter cover bolt it seems like it would still be a pain with the stud and nut. I may give the header a bit of a tweak like you mentioned but knowing my luck I'll crack the pipe or something along those lines. I will look into making my header bolt a stud, I think a have abit of room to play with as far as I can remember, if I don't have room to get the flange over a stud I will see how long the longer bolt will hold up and if it lets loose I won't be any more far behind then I already am right? wish I had my own garage so I could get away from the old lady and tinker every night but that's just not in the cards, I only get to go to her parents and play in the garage on weekends where the bike is stored.

Thanks Jeff

 I may give the header a bit of a tweak like you mentioned but knowing my luck I'll crack the pipe or something along those lines.


I would only attempt such a thing with the stainless header (which is about as tough as headers are made).  Don't see myself trying it with titanium.

My bad thought you were talking about the stock header. Wouldn't an after market ss header go around the cover? Or not necessarily?

Not the DRD, no.  It drops farther than normal in order to clear the radiator lowering kit they sell.

Ahhh ok learn something new everyday. So if I can swing the stud idea the bolt is 8x20mm so if I just get a good length 8mm (5/16) bolt I can make it to the length I need once I take a closer look. But I have no idea and can't find out what pitch this bolt is, would I just get a ss bolt or a hardened bolt?? And should I put anything on the threads of this stud before I put it into the head?? I guess it would depend if I ever wanted to take it out.

Or you could buy Yamaha part # 90116-08022-00 exhaust stud.  Just an idea.


The threads are the standard M8x1.25

Ya could do that. I'll see how long the dealership will take to get it to me. If it's to long I'll just go buy a stud somewhere. Thanks

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