crankshaft binding

I'm currently rebuilding the engine of my '98 XR600R and have arrived at the crankshaft, but if possible I want to try and avoid splitting the cases.

When I turn the crank by hand it feels like it is binding slightly, a notchy click stop type of binding that I can only describe as being similar to head-stem bearing being a little to tight. There are 12 "notches" or click stops in one 360 degree cycle, maybe corresponding to the number of ball bearings in a race or perhaps this is caused by one of the driven gears such as the balancer or clutch? There is some blueing of the crank around the big end of the con rod, so it's run very hot at some time in the past.

Is this slight notchiness (is that a word?) normal or should the crank spin freely? any suggestions appreciated. Tel

sounds like you have bearing troubles start the process of elimanation things that spin when the crank does sounds like one of the bearings is pitted or flat spotted

There is some blueing of the crank around the big end of the con rod, so it's run very hot at some time in the past.

I'm pretty sure the cranks came that way. Probably heat treating done around the rod pin press-fit area. If the roller bearings actually got hot enough to blue the crank, then the pin and rollers would be ground up beyond trash.

Sounds like you may have a bad bearing as stated above. Did you pull apart your oil filter to see if there was any metal in it?

Sounds like a bearing is about to go, do yourself a favor and split that case while you have it apart. All the gears connected to the crank in my XR600R while I had it apart are fine tooth and would not bind just 12 times :cry: , although 12 does sound like a good number for one of the main bearings :cry: (but I didnt count) !!! It would really suck to do all that work and have a bearing go soon afterwords :cry: . Splitting the case fun :cry: hahaha, acutally it is not as bad as it sounds, if you are mechanically inclined and have a manual... If you dont that clicking sound will haunt you everytime you ride :cry: weather it comes apart or not !!!

Call up XRs only and ask them it may just be a normal affect caused by the balancer gear or clutch gear mesh or magneto affect, blueing on the crank is normal heat treating, good luck

remove the flywheel and then see if it is notchy when you turn the crank

Well, after dismantling the engine part by part I found out what the "problem" was. The slight binding I felt was in fact the magnetic resistance from the stator. There are about twelve poles on the stator that matches the lumpiness I felt while turning the crank. As soon as the alternator cover came off the crank ran super smooth. Pity it was the last thing I checked but I guess thats better than the alternative of having dud main bearings.

process of elimination was a sucess one cover removed and the problem solved

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