72 CB500 Four engine stuck

D

djckay

New Member
Hey all,
So several months ago I bought a nasty ratted out, non-running CB500. I have rebuilt the engine, new rings, gaskets, valves lapped, the works. Rebuilt carbs, front forks, new electrical including Dyna S ignition and coils, reg/rec, replaced the missing front brake and plenty more. Now that it is almost back together, just finished building a new wiring harness, and am ready to get it started, the engine won't turn. The kick-starter won't move the pistons.
The engine was free and moving before I started the electrical. It did sit for a couple months while I moved states. Now I have tried everything I can think of. I have let it sit with ATF and seafoam in the pistons. Put it in gear, pushing and dropping the clutch. I cant get the engine to budge. Does anyone have any thing else I could try? I have thought of pulling the engine and cutting the cam chain to get access to the jugs, but I don't really want to rebuild the engine again and sink more money in to this bike.

Thanks
 
Have you tried to turn the crank with the crank bolt. Transmission in Neutral and the plugs out.
Try to eliminate the transmission from the equation. What about using the starter?
 
Transmission in neutral, plugs out, valve cover off. I haven't finished wiring the starter yet, will do next chance I get. I've already destroyed and replaced an ignition advance trying to turn the 23mm nut, won't do that again. Sorry for my ignorance, but the crank bolt, is that the bolt on the alternator rotor?
 
Yeah as above, you can try turning it over using the bolt holding the stator rotor to the crank (LH side, under the alternator cover).
Maybe your kicker mechanism isn't assembled correctly. What state were the cylinders & pistons in?
 
Really odd. So the motor was turning over after you did rings, valves and everything. It turned over after you had fully assembled it and sealed it all up? If you had oiled everything up during assembly, there's no way a few months would somehow seize the motor.

So what I want to know is, what exactly happens when you try to use the kicker and start the bike? Do you get halfway down the stroke and it stops? Does it full stroke but not engage the Pistons? Does it move at all from top position?


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So the crank bolt loosens when I turn it CCW, but no movement in the engine. The kicker will moves a few degrees down while in neutral. Pulling the clutch, the kicker goes through it's full range. When in gear, the kicker will spin the back wheel. But in neutral, clutch out, no love. I didn't split the case and go into the bottom end/trans at all based off how clean the top end was. I figured I would get her running and see if the trans needed any work. The motor was spinning when I bought it, and after the top end rebuild, but then it had to be trailered up to Oregon and sat for a couple months. Would the rings rust that fast? It did see some moisture in the journey and sat outside covered for a couple very wet months. I'm thinking my options are boiling down to pulling the engine, cutting the cam chain to get access to the pistons. I'd rather not since she was a few good days work away from starting, but I'm running out of ideas otherwise. It's been 3-4 weeks sitting with ATF/sea foam/pb blaster and no movement. Thanks for your help, it's my first time diving this deep into a build and I'm getting really frustrated.
 
It doesn't take much, or long, for rust to form.
How much force were you able to get on the bolt before it started undoing? Personally I don't think it would be catastrophic if you were to turn the engine backwards ( bolt clockwise) a small degree - that said, if it didn't turn in the correct direction under a decent amount of force, it might be better to investigate why.
You might not have to cut the cam chain, depending on whether or not you get lucky with where the sprocket bolts happening to be sitting - I lucked out & was able to get both bolts out on my seized motor.
 
Well, I won't be able to get the cam sprocket bolts out; one is at 11 o'clock and the other at 5 o'clock. I can get the top one, but the bottom is too deep in the head to get a wrench, and will hit the tunnel before its out. I tried turning the crank bolt clock-wise, but it tightens to the point I'm scared I will break the bolt without the engine turning at all. I have wired up the starter and given that a shot. The starter motor spun for a couple seconds, then stopped. It sounds like it is trying to move but is being held up. Still no love from the kickstarter, no movement at all anywhere. So I guess I'm back to pulling the motor and cutting the cam chain so I can dig in to the cylinders, unless anyone has any other suggestions.
 
Try heating the cylinders with a propane torch? Might just expand enough to free up some frozen piston.
 
I'm betting this is clutch related? I just had almost the exact m symptoms from a clutch problem. You've tried hand cranking the engine from the right hand side under the points cover? Is you clutch basket on the bike and the spring plate all the way tightened down?


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I'll be getting back into it later this week. The clutch works fine. And yes I have tried cranking on the timing advancer, and had to order a new one as it broke. I may be a novice mechanic, but that is horrible advice. The plan of attack is to heat the cylinders with a torch and keep gently working at it.
 
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