Head bolt Question.

B

Beej

New Member
So after riding my bike for the first break in tank I can see that the lower head gasket from the case to the cylinder is a leaker. There is a couple tiny bubbles that form and there is oil/gas around the thing. Anyhow, question is when I go to take out the head bolts so I can make a new gasket 3 of the 4 bolts come out with the studs still attached. Only one nut actually comes off itself. Should I put some loctite on the stud and let it dry then try to get the nut off again? Does it matter when I go to put them back in?
 
man, you're having nothing but problems...:)

the proper way to remove and install studs is to take two nuts and tighten them down against each other. this will lock them together.

then just unscrew the stud in or out with a wrench on the locked nut.
 
Thanks Baird, throw some more salt on that wound why don't you. ;) She is a bit of a headache but they are problems I can fix, SO FAR. Still running pretty rough though. Harsh chugging type of vibrations not the constant numb your hands type of vibrations. I have maybe 3/4 a tank through it so far. Not sure how "normal" that is....
 
Beej,
In my experience I've run across a lot of the chrome acorn nuts that are more or less jambed on the upper end of the cylinder studs. My opinion is that they are sometimes too shallow to take all of the threads extending past the cylinder head. You can clamp the stud in a vice being careful not to squish the threads, and wrench the nut off. If the stud threads are damaged, and many of them are, you'll want to run a die over them to bring them back. I replace all of the acorn nuts with shouldered hex nuts, new flat and lock washers. Torque them to about 9 to 12 foot pounds. If the stud comes out with the nut you'll want to make sure it goes back in tight. Use Bairdco's advice and double nut the stud and screw it back into the lower case before installing the nut on the head.
 
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Would it matter if any threads in the middle of the studs are smashed when clamping? They don't actually thread into anything correct? Only the botton part into the case and the top part into the nut actually use the threads right?
 
No, it will not hurt the stud if the threads in the middle get buggered up. You evaluation of the threads that are used is good. Just be careful to not bend the studs, even slightly.
 
Beej,
To be honest I've never seen a cylinder stud that was threaded in the middle. Unless someone has replaced them with threaded rod there should be an area in the middle of the stud that is unthreaded. I'd like to see some photos of your studs. I'm certainly not familar with every brand of 2 stroke out there but all that I've seen and worked on have studs like I described. Threaded on the ends only.
Tom
 
You happen to know what size the head studs are on the BGF kit? I figure while I got them off and out I may as well switch them to some quality. Are they 6mmx1.0 8mmx1.0 or 8mmx1.25?
 
If they are the same size as the mount studs or intake/exhaust they are 6x1.0. If not they are either a 8x1.0 or a 8x1.25 Overlap the (a 6mm and a 8mm) studs thread to thread and if a PERFECT fit they are the same. If not it's a 8x1.25 6mm come in 1.0 only. Unless a special thread is requested, which isn't often.

Replace OEM studs (what a grade 3?) with a grade 8.8, (all thread..Do NOT USE bolts if using locktite) about the same as a US grade 5 (anything more is overkill and useless, waste of money). I locktite ALL studs and use either double locking nuts or nylon locking nuts and sometimes both. Trash those acorn nuts, they are nothing but junk.

6mm torque between 50 - 65 INCH POUNDS
8mm torque between 150 and 204 INCH POUNDS
These torque figures are because of the cast aluminum not what the studs can take.

If the gasket is not messed up I'd use some Indian Head sealer or non hardening permatex, or something of the sort.

Me either 2 Door
 
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Thanks for that. I will check it out. Should I not just make a new gasket out of the good gasket paper I have?
 
You can make your own cylinder base gasket out of gasket material if the material you have is approximately the same thickness as the material the factory uses. If you use thinner or thicker material it will affect the cylinder port timing as you will be lowering or raising the cylinder in relation to the piston, thusly changing when the ports are covered and uncovered as the piston travels up and down. Some folks actually do this on purpose to tune the engine. Also, if you raise the cylinder it will reduce your compression ratio.
You will have to pay special attention to the transfer port areas when you make your own gasket. You do not want to leave any excess material sticking into the transfer port which may affect the flow. Also if the gasket is too narrow it will make it easier for the gasket to blow out.
 
Head bolt/stud threads were a topic of discussion some time back. I maintained that every engine with the exception of one that had a previous owner, had different threads on the ends. One end was a 1 thread, the other a 1.25 thread. The fine threads went into the block, the course threads were at the top, cylinder head end. I know this because I was going to replace the studs with long bolts but in all my searching I could not find a bolt long enough with fine threads. Every supplier in the Denver area told me the same thing: At the length I needed, I think they're a little over six inches, if my memory serves me, metric bolts are course thread. I didn't feel good about retapping the case so I went back to the original studs and have never had a problem with them except to replace the acorn nuts with hex. Anyone else ever tried to find a 6" X 8mm x 1 thread bolt? Let me know if you found them.
Tom
 
I do believe my gasket paper is thicker. What is the best way to seal up that gasket? Would the red RTV high temp work or something else? Seal all?

2Door I was looking at these.
Sick Bike Parts
 
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I highly recommend Hylomar. Available at most any auto parts store. Is easiest to apply it with a Q-Tip dipped in acetone to spread it around. Apply it to one side of the gasket and the other side of either the crankcase or cylinder, whichever would be the opposite side of the gasket that you coated. A little goes a looong way, you do not need to apply it thick. It is a remarkable sealant and can even be used without a gasket if necessary. (use a gasket with these cheap engines)
 
Beej,
SBP offers a good product but if your studs aren't damaged I see no advantage to replacing them. If the threads are rough you can buy an 8mm die to bring them back to usefulness. Not trying to take business from SBP but I hate to see guys spend money when they don't need to.
Tom
 
That gasket should fit fine.
Most sealants do not stick well to an oily wet gasket. I rinse a wet gasket with brake cleaner before applying sealants. Be sure that the oil is gone from the surface. Oil soaked into the core of the gasket usually will not cause a problem.
 
That gasket will be here in a day so I will just pop in the fresh one with some sealer and call it a day.
 
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