Crankshaft Bearing Play???

Hey guys. I have a 82 KZ750-E3. Theres a "knocking" in the engine and i suspect that a bearing holding the crankshaft to one of the rods has some play in it. However, before i open the baby up (which i am really not looking forward to), i was wondering if anyone had any advice on some preliminary checks that i have not thought of that might solve the problem. And, if i do have to open her up, i was looking for any websites that could help me through it, since i have only performed this procedure on a car, and would appreciate a guide to work with. thanks for any help.

Hi 750 man, Does the bike knock while running? You can find out by pulling each plug wire one at a time while it's running and the one that's noisy will stop knocking when that wire is pulled. It could also be a noisy cam chain, or clutch basket, it'll keep knocking whether you pull a plug wire or not. Check these all out before tearing into the engine. I would bet that is the problem and not a rod knock. Maybe some of the other guys can add something to this. Bob

yeah, turn the idle up and start pulling plugs. Dont forget to ground the plug cap you pull off so that the opposite cylinder will fire.

Good luck.

If the knocking goes away when it gets hot, its probly piston slap.
If it is a heavy clunking from the front bottom end, worse at lower rpm, likely crank.
If it gets really rattly, worse/louder at high rpm - it could be rod@crank/wristpin.

Good luck.

My buddy and I both went through rod bearings on our 750's. My bike acquired a bad knock and felt gutless. Tearing into the bottom end showed that I had spun a rod bearing, one was wedged under the other :S. A year later the same thing happened to my buddy's. But like everyone said, make sure you rule out all possible other options before you dive into splitting cases

It is definitely making a knocking sound. Havent had a chance to pull the plugs and check yet. Although it is an 82 model, it only has 13,300 miles and Im hoping it is something simple. First bike for me so obviously it is sentimental.