keep snapping base studs

[973trx250r87]

ok need some help went riding today for about 1/2 hour and one my way back home i noticed as i was trying to idle home my engine was racing and there was an strange noise. as soon as i got home and shut it down i noticed that a base nut and half the stud was missing, this is the second time the same stud has done this.... any advice on what to do or what might be causing it ???? thanks

[Honda 250r 001]

What are you torquing the base nuts too?

[973trx250r87]

I went a 1/4 turn past snug both times on all 4 which is what doesn't make sense if I had over tightened them shouldn't they all be braking? Why just the same one twice ?

[RyanWsly]

take a picture of the top of the broken stud and post it on here. Guessing you have a fatigue break because something isn't fitting up square or solid. Did the break start in the root of a thread and is it smooth with little arched lines in it for the most part? A picture would be very helpful.

[973trx250r87]

Ill get a few pics 2mro after work if it helps at all the place I bought my bottom end from the owner was a hack

[jcs003]

did you torque/tighten in a criss-cross manner?

[C41Xracer]

Originally posted by 973trx250r87
I went a 1/4 turn past snug both times on all

[C-LEIGH RACING]

?? Head stay in place ??.
Neil

[Burns310r]

Are you using new studs, or old ones?

[973trx250r87]

Yes I tightened them in a criss cross pattern and the first time the stud broke I'm assuming it was new and the second one was new

[atvmxr]

Originally posted by 973trx250r87
I went a 1/4 turn past snug both times on all 4 ?

w t f ?? :eek2:

torque wrench... do it right...

[Honda 250r 001]

Originally posted by atvmxr
w t f ?? :eek2:

torque wrench... do it right...

Some of us cant use a torque wrench because of aftermarket PRO X cylinders.

[DnB_racing]

Originally posted by atvmxr
w t f ?? :eek2:

torque wrench... do it right... its more than likely not breaking because of not being torqued!!
more than likely something is slightly twisted, either a mount or frame, or the head stay, could even be a cracked frame causing this

[RyanWsly]

I'm with DNB, I would just like to see that picture though, it should tell you what is going on. The type of break should tell you if it is suddenly breaking or slowly breaking, slowly like if the lower engine is moving and the head stay it tight or sudden like something is broken and getting put in a heavy strain all at once. If the stud was over torqued the stud will have a smaller diameter around the break area, imagine pulling gum or something apart until it breaks.

[973trx250r87]

Agreed my 1/4 turn method is not the way to do it. Ill post a pic after work and I'm running a cool head without a head stay mount, I know the head saty had been brought up could that be an issue?

[Honda 250r 001]

Originally posted by 973trx250r87
Agreed my 1/4 turn method is not the way to do it. Ill post a pic after work and I'm running a cool head without a head stay mount, I know the head saty had been brought up could that be an issue?

Yes i'm sure it could be an issue if your running high compression and race fuel or alcohol or something. What is your motor setup?

[C-LEIGH RACING]

973trx250r87
Agreed my 1/4 turn method is not the way to do it. Ill post a pic after work and I'm running a cool head

""without a head stay mount"",

I know the head stay had been brought up could that be an issue?

Yes, and untill you put the head stay back in place, mounted to the head,, it will keep right on breaking base studs.
Neil

[RyanWsly]

Neil, I'm just asking if it's a pattern you've seen, but why would that be doing it? possibly the the way the engine is specd? I wondering because I know you can buy heads with no head stay and I'm pretty sure some of the aftermarket frames are not fitted with a head stay mount.

[atvmxr]

Neil, are you saying that not running a head stay will cause base studs to break? or once you have really high compression, then the head stay is necessary?



who ever mentioned the pro-x cylinders - I didnt think of that, but cant you use a crow's foot extension?

[C-LEIGH RACING]

Well, I went for a few years myself running with out the head stay on the R & had a few studs break, before I learned better.

You see, when you pump a 250R engine up for high performance, which would be just about any amount of compression over what a stock engine would have, whole time your running it hard, it is trying to rip that cylinder off those cases & just a mater of time before those studs give up.

Now I dont know why, but every one we had to break, was on the clutch side.
Just as a guess, it could be maybe theres more stress in that area of the engine between the case & cylinder, but I have no explain for it.

After we started back mounting the head stay in place, we've had no more case studs to break.
At the very least, just so you have it in place, if you got to use a smaller bolt through the head then do so, just so the stay will be in place to support the cylinder.
Neil

[jcs003]

i opted to use a smaller bolt through head with a nylock nut and just tightened it until it was flush. i did this because i kept blowing head gaskets and thought there might be an overload in that area. i assumed frame flex was the cause for the overload in that area so i went with the smaller bolt and havent blown a gasket since.

[trx293pv]

Are the dowels in place? If the cylinder is in a bind or cocked one way or another when he's tightening the base nuts this could cause problems.

I know for a fact that Roll frames don't even have a place to mount a head stay btw.

[utah250r]

I had the same problem with a pro-x cylinder. The recess in the cylinder where the stud went through wasn't perfectly flat and it kept causing the bolt to break. I got it fixed and I haven't had a problem in 4 years.