Crankshaft Issues and ??'s

My wrench called me a few minutes ago. Told me that when whatever event bent my valve, also must have pushed the position of the (?)lobe on the crankshaft.

I don't know much about the specifics of the motor and I want some input from you all, before I sit down with him.

I have a 1981 kz1000 m1 CSR. I had to remove the head some time back, and when I lifted on the head, the cylinders came with it, breaking the seal on the lower gasket.

So we decided that he shouldn't split the cases, but would work from there up to do rings, etc.

He says these cranks are pressed together. True? (I gather so from the other crank thread)

Does this mean a complete tear down?

Where would I get the tchnical data for the (Stock)crank configuration?

Is it easier to buy a new crank shaft?

Thanks for any help.

yes crank is pressed together,bending a valve probably didnt affect crank but you can pull head and cylinder back off and pistons.then take a 17mm drill rod and run it through small end of rods 1 and 4 then bring 2-3 up and repeat as long as rod slides through your crank should be straight

Plummen is right. Even though these cranks can slip it takes quite a bit more than a bent valve. Use the trick Plummen stated. If you can get a 17mm rod long enough to go threw all four wrist min loops at the same time is best, if not than just two is good enough and there should be a position where two adjacent rods should line up so you can slide the 17mm pin threw them. check from 1to2 2to3 and 3to4 if you can slide the pin threw the crank is straight.

Couple of things.. When you check the crank with the 17mm pin, it has to go thru all four rods if the crank is straight. If it is twisted, it will usually go thru 3 rods and not the 4th. Holds true no matter which way you put it thru.

Next. If the head and block are on, it is easier to check if the crank is twisted by using a degree wheel. Find TDC on #1, then check #4 if it is not the same, the crank is twisted.

Thanks for the advice. I talked to my wrench and we have left it that he will split the cases, pull the crank, and I will be responsible to have it worked on.

So, now I need to know what I might want to have him check before removing the crank. I have seen it and there is a considerable difference between the position of #1 and #4 pistons.

Plummen and Ape jay, your recommended approach should be done before dismantling the lower end, right? If they do not line up, then how do I go about having it corrected? Are there guys out there that can do this per specification?

I would just be interested to know, what you did to twist the crank. I have put over a 1/4 Million miles on all of my bikes and i never managed to have this misfortune (Knock-Wood). I did however buy a spare crank to have welded just in case. The engine that is in my custom built GPz1150 originally came from an 81CSR.

jay has a good crank guy he can reccomend

What dose it usually cost to have a crank welded?

I have been told by a national champion dragracer here in town that just because a crank is a little out of true, it isn't a bad thing. I sold him a MK11 crank that wasn't perfect as far as being true. He told me that he was told by John Pearson that a crank can be out of true by a few degrees and it wouldn't make any difference. Not until you get way up in the HP ratings would you have to worry about it. How much out before it needs truing I don't know myself, but the way he talked, and this guys builds these motors for a living, he wasn't worried about the crank not being exactly true...even for a dragbike motor. Most of his motors are running low-9's to mid-8's so the guy knows his stuff. Of course, it would be best if it was exactly true, but if this guy isn't worried about it, I'm not going to lose any sleep over a crank that isn't exactly true. They ran these cranks for years with just a weld job before they started to take them apart and index them. Just a thought.

last crank i had checked/welded was only like $90,so its still cheap insurance if motors already apart