Snapped Studs

[djkorn1]

I keep snapping the studs off that hold my cylinder down to my cases. The nuts on these studs are also coming loose all the time. I rode three minutes today before one snapped causing a HUGE air leak! (nasty) Any ideas on a permanent fix?

I can't seem to be able to keep the cylinder down and tight. :Banane19:

btw...cases and cylinder are stock with no modding, porting, decking, etc...

 

[BruceSki]

Buy a superjet?

 

[djkorn1]

nah...don't like slow skis.

 

[SuperJETT]

You could try safety wire, but breaking studs and nuts coming loose is typically a sign of detonation in my book. I'd look at your tuning.

 

[djkorn1]

I have to pull the cyllinder off anyway...I'll look for signs of deto. What is safety wire?

My brother thinks the old studs from 1996 are stretched out from being cranked down too hard....maybe replace all the studs? or just use bolts?

 

[NVJAY775]

you could try safety wire, but breaking studs and nuts coming loose is typically a sign of detonation in my book. I'd look at your tuning.

x2
It's a bummer when you know your ski is unreliable.

 

[djkorn1]

I think it was because my carb linkage was loose...causing it run poorly...

 

[NVJAY775]

Sweet! Glad you got it figured it out. A couple months ago my throttle stuck. My dust boot on the cable came loose, got stuck and away I went... Good times. Awesome it's a simple fix.

 

[rollin5150]

With as many times that you have had this motor apart, I would replace all studs and caps. I run a very similar setup to you and I have never had one come loose. Are you torquing the studs to the proper spec or just wrenching them down?

 

[3rid]

Ìt happen to me too and after further inspection the cylinder was cracked...
so maybe something to look for...

The carbs are in front and hidding it well so it's only when we took it of we could see it really.

 

[yamanube]

Don't replace them with bolts.

 

[NVJAY775]

Interesting on the cracked cyl.

 

[Waternut]

Funny… I always made fun of people who ran girdled heads on kawi’s because their cylinders are so much stronger than SJ’s. I always those those girdled head were more gimmick to scare the kawi guys into spending more money. Guess you’ve managed to prove me wrong.

I've had similar problems with my factory head pipes on both my SJ and kawi. I tried everything to lock the bolts in place including JB weld but nothing worked. The main issue is that the threads on either the studs or nuts are worn out. I finally fixed the problem on my kawi by swapping to studs over bolts but that doesn't really help you. I did use safety wire for a while but it's a PITA to replace after you've removed something. My solution on the SJ was to use helicoils and crank the bolts down to about 35 ft-lbs instead of like 20-25 as was called out and I ran crankcase sealant in the threads to reduce vibration. Maybe one of these will help.

 

[djkorn1]

Mine was cracked the exact same way....in the exact same spot. Sucks.

Ìt happen to me too and after further inspection the cylinder was cracked...
so maybe something to look for...

The carbs are in front and hidding it well so it's only when we took it of we could see it really.

View attachment 136664

 

[nick chastain]

U might want to check the crank and lower rod bearings if your getting that much vibration to cause cracks and broken studs.