Zonablazer wrote on 02/17/16 at 04:32:55:


The problem is not the bolt.....the threads that strip are the ones in the aluminum cylinder casting. Folks just seem to want to crank a lot of torque on these small bolts, and they really can't handle it.  If folks are trying to torque to 6-8 ft/lbs using their 150 ft/lb torque wrench.....they stand a good chance of over torquing the bolt and stripping the threads (My 150 ft/lb torque wrench is just about useless for anything less than 30 ft/lbs....the click is so weak that you can't hear or fell it at low settings).

I do believe that anytime I have a cylinder head off in the future....I am going to just go ahead and install the helicoil insert while the engine is apart.

Dave,
Would it be possible to drill the hole a bit deeper and cut new thread?

Let us know how it turns out.

Actually if there's enough meat there that'd be a great option here, not a helicoil but a threadsert, if they make them in that size
I used theos to fix stripped spark plug holes a few times, and they were like 1000x better than screwing  steel threads into aluminum
negated the need for never seize, too

norm92de wrote on 02/17/16 at 07:53:13:


I don't believe it would be possible to drill the hole any deeper - or you will drill though the bottom of the casting.  I have posted a photo below to show which hole is stripped.  This hole is in a small "boss" cast in the side of the cylinder.  it is a "blind" hole that does not extend out the side of the cylinder.  If you tried to drill it much deeper you would make a hole in the bottom.  It may be possible to use a bottoming tap and get a few more threads in the existing hole.  


And the potential for for installing a threaded insert, helicoil or larger bolt really isn't an option when the bike is fully assembled.  The bolt is 125mm long (5"), and it passes through the head cover, through the cylinder head, and into the cylinder.  The insert/heli-coil is easy when the head is off - but not when the engine is assembled.  The threaded portion of the hole is the bottom 14mm at the top of the cylinder....so you have 111mm of head cover and cylinder head you have to negotiate to get to where the stripped threads are located.

Dave,
I completely misunderstood the situation!  

I thought that the female thread was in the head not the cylinder, duh.
I can see that you will have a devil of a time without removing the head.

A Helicoil or a larger thread may be your only options if your plan doesn't work out.

Be sure to let us all know the outcome.

I've been meaning to respond to this for a while. Dave not only made the part for me, but came over to my place and installed it - turns out he lives about 10 miles from me!  It worked perfectly. He had to tap it gently with a hammer to get it to bite, but once it bit all was well. I took a pic of the fix, I'll post it post haste.

And BTW - THANKS DAVE!!! You're  a lifesaver.

Now the irony is that it turns out the nut in the cubby next to the exhaust port was leaking and my whole cap-leak repair may have been completely unnecessary.  Ah well, at least it won't need to be done again.  

It's a bit sputter-ish. Seems like it's not very happy at low-mid throttle, almost acts like it's starving for fuel in just that spot. Seems ok everywhere else. But yeah. It works!  

ghryx wrote on 05/12/16 at 16:10:35:


I have ridden a couple of bikes that did that....mine included.  It just needs a carb cleaning, rejetting, and a white spacer mod.