Guys, I've tried every HD tech I could find, and all the aftermarket books available, and can't find an answer to this one.
This bike was mine new (2005 883XL), sold to my son, who put a 1200 kit on it. Twice now he's blown head gaskets, caused because the cylinder studs on the intake side appear to be too short! I didn't realize what he was doing until I went over to help on the latest rebuild.
What's happening is that there is only about 1/8" of thread connecting between the stud and head bolt (again, on the intake side). Clearly not enough to hold a torque.
Anybody ever have this problem? And how'd you overcome it?
Thanks.
Frank

 

i would lock to nuts together on the studs and twist out the stud using the bottom locked nut and see how much is down in the engine base. just a suggestion

 

How can you tell how much of the stud is connecting when you have the head on there?

There really isn't a whole lot of stud that is exposed when the cylinders are on (no head). Like you said, maybe 1/8" - 1/4" of exposed thread on top of the cylinder surface is all there is.

I don't know how experienced you are, but the torquing sequence of the head bolts is extremely important. If done wrong it can warp your cylinders and heads. Also, when you pull off the cylinders, you must be super careful not to hit the studs. They can bend minutely and are no good then.

If that is done wrong, then the studs could be wrong, the heads or cylinders could be warped, both of which would cause uneven loading and lead to blown head gaskets.

My advice is to measure the heads, cylinders, and studs to make sure they're all level and straight to spec.

 

Thanks guys.
Rymax: I've asked the son to take that measurement but haven't heard back yet.
Scuba: Very careful to torque in correct order and to specs. Where I see the problem is when I dropped the head bolt onto the stud, through the head. There is only about 1/8", or less, to start the bolt. Ya just can't squish the base or head gaskets enough to get sufficient thread contact to properly hold the bolts in place.
My impression is with Rymax's suggestion, in that perhaps the studs are being threaded too deeply into the "block". What I'm not able to come up with is how far into the block to set the studs, or if the studs being used are incorrect. According to all the techs and books, they're the proper studs.
I'm stumped.

 

Ok. In that case I think you and Rymax are right. The studs should have a shoulder on them, kinda like a washer that is built in to the stud. You thread them down to that point and tighten them to ~12 ft-lbs.

Since it was a 1200 kit, another possibility is the new cylinder (unless you bored your old ones) is taller than the original.

 

[Deleted] Double post.

 

Tell your son he's not supposed to be using the cylinder stud gaskets. More than likely thats what he's doing....... Thats why his studs seem so short.

 

Is he letting it warm up properly? He needs to let that bike warm up a bit before getting into it or he will blow head gaskets all day long.
I was blowing head gaskets left and right. I had the cylinders trued and installed reverse dome pistons to lower comp. a bit. She runs like a dream now.

 

Warming it up doesn't seem to be the problem.
Freebird, what are you referring to when you say "stud gaskets"? We're using new cylinder base gaskets and new head gaskets each time. Am I missing something?
If I can, I'm attaching a cell phone picture I took when I laid the intake side cylinder head bolt onto the stud. This is all the room there is for threading, which clearly doesn't seem right. And just for fun, I'll throw in a photo of the gasket. Never seen one blow this big.

 

Some gaskets use separate a viton o-rings around the dowels. If your using Cometic Gaskets then you wouldn't use those. Judging by the problem your having if you do have the O-rings on the dowels I wouldn't use them.....