If you find that the head nuts are out of spec, then it is quite possible that a cylinder stud got "pulled" a bit and may later on strip out on the threads.
Ask the Indians what happens when you don't control immigration.
Duane Ausherman wrote:If you find that the head nuts are out of spec, then it is quite possible that a cylinder stud got "pulled" a bit and may later on strip out on the threads.
please elaborate. I'm waiting for the insurance adjuster to come look at my expensive mess so I can't touch it but will be going at it as soon as I can. (I was going to just sell the whole thing, couldn't take the heartbreak, but I have to fix it. There is no question and I am strangely compelled). I also have a 78 R100RS Motorsport in pieces so this might be the perfect opportunity to put it together using the 77 R100 as a donor bike.
Duane is talking about the impact that the cylinder took, and how that can stress where the bolts thread into the case. I would be far more worried about that than metal from the damaged valve covers. The only thing i'd worry about on the heads are if the covers were compromised enough that the rocker/valve gear actually took an impact, but I wouldn't be worried about the valve cover metal. Change the oil, filter, and covers, and that should all be good.
Major Softie wrote:Duane is talking about the impact that the cylinder took, and how that can stress where the bolts thread into the case. I would be far more worried about that than metal from the damaged valve covers. The only thing i'd worry about on the heads are if the covers were compromised enough that the rocker/valve gear actually took an impact, but I wouldn't be worried about the valve cover metal. Change the oil, filter, and covers, and that should all be good.
how do I check the mounting studs for damage? Is there a way to know if I've stressed them?
I shoulda kept my mouth shut, once again. I have no answer.
The problem is that as the valve cover hits the ground, it gets torqued a bit sideways. Then the entire head/cylinder becomes a lever to put great stress on the bolts. It wants to pull them out of the case. It is possible that this stress can weaken the threads that will only later fail and pull out.
I actually suspect that many/some of the engines where the threads have pulled out were due to a crash. I have no proof. We were discussing this way back in the day when the first few studs pulled out.
Sorry for opening Pandora's box.
What I would do is to torque the nuts and loosen them a few times. Each time checking the feel as they tighten. You may be able to excaerbate the situation to the point of failure, or some indication. You really want the insurance to pay for this one.
I profess ignorance and take no responsibility.
Ask the Indians what happens when you don't control immigration.
well said, Duane! I've often wondered why the studs would pull out if they're being properly torqued. I've always "backed" into it. Torque in stages, not all at once and using a torque pattern. So the answer: there is no way to know until it happens. OK, so here is another question. Is it possible to calibrate a torque wrench? If it's a beam torque wrench is there any way to know for sure the reading is right?I have both style torque wrenches but prefer the beam style for precise torque. any other opinions out there? That may be a question that is like the "best tire" question.
