Half the threads in the left intake mounting hole are stripped out.

R

Rusty_Nail

Active Member
When I first put the studs in the left side of where the stud goes into the cylinder head are stripped out even though I only tightened it until it was snug. Could the threads in the hole have already been damaged from the factory? The one on the right is solid no problem, but the left one when I put the nut on the stud and start to snug it up it will just keep turning and turning and doesn't get tight. What should I do? Can someone provide a link to a replacement 49mm cylinder or replacement 49mm top end? It's supposed to be a 100cc but I know it needs the 49mm cylinder.
 
I would try permanent loctite first, coat the threads and bottom the stud and let it dry according to the instructions, if that doesn’t work you can tap the hole one size larger. A lot of people have tapped them to sae course threads
 
Rusty_Nail said:
When I first put the studs in the left side of where the stud goes into the cylinder head are stripped out even though I only tightened it until it was snug. Could the threads in the hole have already been damaged from the factory? The one on the right is solid no problem, but the left one when I put the nut on the stud and start to snug it up it will just keep turning and turning and doesn't get tight. What should I do? Can someone provide a link to a replacement 49mm cylinder or replacement 49mm top end? It's supposed to be a 100cc but I know it needs the 49mm cylinder.
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A common fix for stripped 6mm threads in aluminum motorcycle cases is to tap the hole to 1/4" x 20
It's so close ya don't even need to drill the hole first
Just tap the stripped hole with a 1/4"x 20 blind hole tap


1/4" x 20 is the next bigger thread size to 6mm.
It's a more course thread and it will be less likely to pull the threads out again

If the 1/4" x 20 thread pulls out then you can still fix it again with a 6mm Helicoil Thread Insert

Stripped Threads are actually Pulled Threads
 
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You need a bottom tap to thread as much as possible, the picture below shows what they look like.
 

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Use plenty of oil, turn the tap in and out to clean out the threads as you go. Don’t go too fast, turn the tap clockwise then reverse, keep the tap as straight as possible as you start it.
 
Well guys, so I tried the red Loctite. So far I've taken it on two shorter rides and far as I can tell so far it's holding. Hasn't acted like there was an air leak on either of the two rides so far. The other reason It was sounding like there was and air leak is I found the new carb I bought was a pos. It leaked fuel which isn't safe, and the bike would just rev hang, or sloooowly drop to idle, or it would just try to rev out all the way. I put my OLD speed carb on it and runs perfect at the small cost of it being a slightly smaller carb. But it rips hard so far on my 36t sprocket and put a smile on my face soon as I ripped it a bit :D
 
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