Author Topic: cb750 cylinder studs and main studs  (Read 3925 times)

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Offline KRONUS0100

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cb750 cylinder studs and main studs
« on: December 02, 2011, 02:06:58 PM »
have done some reading, but still got a question or 2.  are these new HD studs really that fragile that they are breaking in the head torque sequence?  and will the stock rubber dowel pins and acoompanying o rings go over these studs?  Getting ready to replace the old stock ones on my motor due to recent issues, and am even considering replacing the main bearing bolts with studs as well.  thanks.
MATT
current bikes:  1976 CB750F, 1981 GS1100E
bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E

Offline Terry in Australia

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Re: cb750 cylinder studs and main studs
« Reply #1 on: December 02, 2011, 02:24:50 PM »
I've built 2 engines with H/D cylinder studs (NOS RC studs on one engine and APE on another) and had no problems with either set. I torqued them down to around 25 ft lbs from memory, with no leaks. They'll work fine with your dowels etc. I'd certainly rather use them than the standard "stretchy spaghetti" OEM schidt studs. I haven't used the bottom case studs yet, but I plan to when I rebuild my engine soon. Cheers, Terry. ;D
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Offline KRONUS0100

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Re: cb750 cylinder studs and main studs
« Reply #2 on: December 02, 2011, 06:03:44 PM »
thanks Terry.  wound up with an oil leak on my 72 motor due to reusing the factory studs because money was tight.  doin it right this time round.  goin with a 2cd size over bore job...dont feel the need for an all out 850 kit.  will be using the webcam 41a camshaft, allready talked to dynoman performance about it.
MATT
current bikes:  1976 CB750F, 1981 GS1100E
bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E

Offline MCRider

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Re: cb750 cylinder studs and main studs
« Reply #3 on: December 02, 2011, 06:11:10 PM »
And I wonder, and its my position, that you don't have to crank all the way on the HD studs. Even though they may be good for 25+, why would you. Stock being 15-18 ft lbs, I think, being able to take them to max +10% in a consistent manner, knowing they won't stretch or distort is enough to accomplish the goal and minimize the chance of breaking.

I say go to 20ftlbs and it won't leak.

Maybe more if a turbo is involved?   ;)
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Offline Terry in Australia

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Re: cb750 cylinder studs and main studs
« Reply #4 on: December 02, 2011, 06:53:39 PM »
Yeah, I wouldn't be too leery about 25 ft lbs though Ron, the Ape studs are the same dia as the "Waisted" portion of the studs in my Suzuki GS1000, and the torque setting for them is 36 ft lbs. The Ape studs for my GS1000 can be torqued to 42 ft lbs! Cheers, Terry. ;D 
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So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline MCRider

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Re: cb750 cylinder studs and main studs
« Reply #5 on: December 02, 2011, 07:31:20 PM »
Yeah, I wouldn't be too leery about 25 ft lbs though Ron, the Ape studs are the same dia as the "Waisted" portion of the studs in my Suzuki GS1000, and the torque setting for them is 36 ft lbs. The Ape studs for my GS1000 can be torqued to 42 ft lbs! Cheers, Terry. ;D
Yikes! didn't know that. A few here have broken the stud at a much lower torque, around 25ft lb. But that was probably an unfortunate fluke.
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Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Terry in Australia

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Re: cb750 cylinder studs and main studs
« Reply #6 on: December 02, 2011, 07:37:33 PM »
Yeah, I wouldn't be too leery about 25 ft lbs though Ron, the Ape studs are the same dia as the "Waisted" portion of the studs in my Suzuki GS1000, and the torque setting for them is 36 ft lbs. The Ape studs for my GS1000 can be torqued to 42 ft lbs! Cheers, Terry. ;D
Yikes! didn't know that. A few here have broken the stud at a much lower torque, around 25ft lb. But that was probably an unfortunate fluke.

Yeah, I don't know who the guys involved were, or their level of experience Ron, but I torque my studs down in small increments, (and the studs are clean and lightly oiled, as are the nuts) and I haven't broken one yet. Cheers, Terry. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)