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bolts for cylinder head/exhaust

1747 Views 5 Replies 2 Participants Last post by  EPR
I recently stripped out the threads on two of my cylinder head bolt holes. I read the thread here about running bolts all the way through the cylinder head and into the back (behind the flywheel) and putting a nut on them.

I did not have any bolts on hand so I went to the hardware store and purchased these 1/4 inch wide 3.5 inch long bolts. As it turned out they were small enough to fit and begin threading in without actually having to drill out the existing holes, but large enough that they cut their own threads along the way. It was awesome. I was able to slowly tighten these into the holes and use them to replace my old bolts. I did have to grind away part of the cooling fins on the head in order for the bolt head to be accessible by a socket, but that was very simple.

While putting everything back together I was a bit paranoid about stripping anything so I failed to tighten my exhaust bolts enough. They fell out on my first ride. Was pretty annoying after the cylinder head ordeal, but in a pinch I used the bolts I had just purchased and once again they did the trick perfectly. I was able to thread the bolts all the way through the hole to get an extra quarter inch or so worth of threads (over the stock bolts) and used lock nuts to hold them in place. I have a pic below. I was pretty stoked about all of this so I decided to post.

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How did you do that?? The threads on the engine are M6 x 1.0 metric, we were taking about longer M6 bolts. Hope them exhaust bolts hold up.
As long as the hold it should work.
Yeah, I went on ebay and bought some m6 bolts, but then I got impatient :). At first I figured any bolt that was long enough to go through and attach to a nut on the other side would work so I did not care about the exact bolt width as long as it was close. It turned out these were just barely bigger than the m6 bolts so as I tightened them in they cut their own threads. I did not even have to put a nut on the other side. It could be that they will eventually break loose and I will have to add the nut to the other side, but I'll use them until they don't work.

As far as the exhaust side goes they feel much more solid than the stock ones and I kinda like the look.
My concern is you wasted the threads in the engine cases. I would just leave them alone now. When you put them in thread sealer would have helped alot. If you take them off now it might ruin the threads for good.
Later if you get an M7 tap w/ the right threads and some M7 bolts, you get drill the hole alittle bigger and rethread it to 7mm
Yeah, my feeling was if that happened that I would just use the bolt trick and be fine. With a bolt on the other side there should not be any need for threads in the engine, correct?
When I stripped one of my cylinder bolts, I ran my M6 x 1.0 tap thru, then a longer 6mm metric bolt thru and a 6mm nut inside w/ blue thread sealer ( medium ).
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