Topic: Stuck Engine not Kickstart

[Blasbo]

I searched but could not seem to find anything similar.
About a year ago I bought a CB750 K7 project. PO said engine was froze and chain was too. Googled how to un-stick and found this forum. I put 50/50 ATF/Acetone in the cylinders in the spark plug holes and let it sit. Every day or so I would put it in gear and rock it back and forth. After a couple of weeks it was still stuck so I was going to try to soak the chain in kerosene. I loosened the rear brake and was looking at the chain. It didn't seem to be binding so I put it in gear on the centerstand and I could rotate the tire. I'm thinking it may not have been stuck at all, just the back break was too tight.

The next step was going to be to work the kick start and circulate more oil around but it won't budge! I can jump up and down with my 190 lbs and it won't move. I can't remember which one, but one of the manuals I have says it could be a broken pawl?

I have not tried the electric start. I didn't think it was wise until I had a better idea of what the problem is.

What should I look at next?

Thanks!

[1timduke]

If the pawl is broken, the electric should still operate, or you could try a bump start if that fails.   

If the bike is in gear and rolls, then I believe the motor should be free.   If you've poured ATF and acetone in the chambers, you may have some fouled plugs pretty quick depending on how much is left in there.   Are there any things obviously wrong with the bike otherwise, such as oil leakage or a lot of rust from being kept outside?

-Tim

[fastbroshi]

   I'm assuming the 750's alternators rotate just inside the stator like the 550's.  If that's the case, you might try taking the cover off and making sure the stator hasn't come loose from the cover.  It did on my 550 and the damn thing wouldn't turn at all.  Removed the cover and resituated the stator, problem fixed. 

[Blasbo]

Thanks for the responses. It's a project so it will be a while before it starts. It's been in the weather so there is a little rust, but no major oil leaks that I can tell.
The thing that had me confused was that I put it in gear and could rotate the tire which made me think the cylinders were free. But the fact that the kickstart wouldn't move made me second guess that it could still be stuck. I was thinking about putting in the battery and hitting the electric start for a second and see if it would spin.
My concern was that if the engine was still actually stuck and I tried the electric start it would tear something up. I have a really bad habit of discovering the obvious after I have totally screwed something up.
On thinking about it I could remove the point cover and and rotate the crankshaft with a wrench. But I will definitely check to make sure the stator is not loose.

[Gordon]

On thinking about it I could remove the point cover and and rotate the crankshaft with a wrench.

That's a recipe for a broken timing cam bolt right there.  That bolt won't take much torque before snapping off. 

[punch455]

+1. Hook up a battery and try the electric start.  If the engine is seized, the starter will just click. No harm no foul.

[jumpjg]

Doesn't sound like a problem with the kickstarter, rather a stuck engine i.e., rings rusted to the cylinder walls. If you put the bike in top (5th) gear prior to rocking it you will have more torque available to turn the motor over, probably more than can be generated with the kicker. I recently un-stuck a CB750 by putting a socket/breaker bar on the alternator nut. You have to remove the alternator cover to gain access (left side of engine, use oil catch pan underneath). The wires for the alternator run under the cover aft of it (gearcase cover?), so the alt cover might be easier to remove with aft one removed first (oil behind that cover too).

I'd use rocking in fifth first, followed by the electric starter, then the alternator nut

Hope this helps,

Joe in St Louis

[Blasbo]

That's a recipe for a broken timing cam bolt right there.  That bolt won't take much torque before snapping off. 

If the engine is seized, the starter will just click. No harm no foul.

Thanks to both. Exactly the type of information I was looking for. I will try turning it over with the electric starter, or the alternator nut but I won't try the cam bolt.
It will rotate in gear, but the fact that the kickstarter wouldn't move made me wonder if it really was free.

[MCRider]

That's a recipe for a broken timing cam bolt right there.  That bolt won't take much torque before snapping off. 

If the engine is seized, the starter will just click. No harm no foul.

Thanks to both. Exactly the type of information I was looking for. I will try turning it over with the electric starter, or the alternator nut but I won't try the cam bolt.
It will rotate in gear, but the fact that the kickstarter wouldn't move made me wonder if it really was free.

Your comment made twice that "it" will rotate in gear has me puzzled. You said you could put it in gear and rotate (implying rotating freely as though it weren't in gear) the wheel. That simply can't be. Even if the engine wasn't stuck when in gear it would be difficult, though not impossible to rotate the wheel while in gear and you would "feel" each cylinder as it passes into its compression stroke. That would be good but it wouldn't be easy.

If you are turning the engine with the rear wheel and feeling those cylinder compression strokes, then all is well. If at the same time, the kickstarter is not turning the engine then the kickstarter is jammed, not the engine. See my point?

So we likely have some terminology problems here, as well as a skip in the logic of diagnosis.

[Blasbo]

Even if the engine wasn't stuck when in gear it would be difficult, though not impossible to rotate the wheel while in gear and you would "feel" each cylinder as it passes into its compression stroke. That would be good but it wouldn't be easy.

If you are turning the engine with the rear wheel and feeling those cylinder compression strokes, then all is well. If at the same time, the kickstarter is not turning the engine then the kickstarter is jammed, not the engine. See my point?

I do see your point. It's been a while since I tried to spin the wheel. I need to go back and put it in neutral, give it a spin. Then put it in gear (5th?), spin it again and compare and like you say "feel" for the compression stroke.

So we likely have some terminology problems here, as well as a skip in the logic of diagnosis.

Yeah, still trying to learn proper terms of things and also work on my diagnostic skills. I do have a problem with that with infernal combustion engines. That was my reason for starting this thread, to see if I'm looking at this properly.

[BobbyR]

If you remove the spark plugs put it in 5th gear and can rotate the wheel, you will hear noise coming from the empty plug holes if the engine is turning. If there is oil in the cylinders you may want to put some towels or newspaper in front of the holes, it can shoot pretty far. If you can put it in 5th gear and the wheel spins freely and you hear no sounds from the plug holes, your clutch is not engaging.

[MCRider]

"Yeah, still trying to learn proper terms of things and also work on my diagnostic skills. I do have a problem with that with infernal combustion engines. That was my reason for starting this thread, to see if I'm looking at this properly."

Good deal. Keep talking you'll figure this thing out. Bobby's idea of pulling the plugs will help as then you could turn the wheel with the engine connected (assuming its not locked up) and not be hindered by the compression strokes. You would still hear the moving parts and feel resistance. Maybe leave 1 plug in and you'll feel that compression stroke when it comes around.

[Blasbo]

I didn't include this information at first because I didn't think it was significant but now I'm not so sure. The clutch is stuck. I pull on the lever and the lever does not move.
Last night I put the bike on the center stand and pulled all the plugs. With the bike in nuetral the back wheel spins easily. If I put it in gear it still spins but ae is quite a bit of resistance. My neighbor put his finger in the 1 hole and I turned the wheel a couple times around. He never did feel any pressure.

I'm stll not sure if my engine is stuck or just my kick start.

[Gordon]

I didn't include this information at first because I didn't think it was significant but now I'm not so sure. The clutch is stuck. I pull on the lever and the lever does not move.

Didn't think it was significant?

[Blasbo]

Didn't think it was significant?

Yeah, like I said, my diagnostic skills suck! 
Since the clutch lever was all the way out I ass-umed it was stuck fully engaged. 
I removed the clutch cable so the clutch fully engages and now the real wheel does not move when in gear. Apparently the stuck cable was holding the clutch partially engaged? In neutral the rear wheel spins easily, but in gear the clutch was engaged enough to increase resistance on it, but slipping enough to allow me to rotate the wheel.
So it looks like I am back to square 1 with a stuck engine.

[BobbyR]

Didn't think it was significant?

Yeah, like I said, my diagnostic skills suck! 
Since the clutch lever was all the way out I ass-umed it was stuck fully engaged. 
I removed the clutch cable so the clutch fully engages and now the real wheel does not move when in gear. Apparently the stuck cable was holding the clutch partially engaged? In neutral the rear wheel spins easily, but in gear the clutch was engaged enough to increase resistance on it, but slipping enough to allow me to rotate the wheel.
So it looks like I am back to square 1 with a stuck engine.

Not exactly, you can now do the rocking thing to break the pistons loose. Have your neighbor come over and stand on the other side while you do it so the bike does not tip over. Keep pouring penetrant in the plug holes. 

[Blasbo]

I recently un-stuck a CB750 by putting a socket/breaker bar on the alternator nut. You have to remove the alternator cover to gain access (left side of engine, use oil catch pan underneath).

Joe,
I thought about doing this, but I was afraid of putting too much force on it and over-tightening the rotor bolt or breaking something. Is it strong enough?

[Blasbo]

You're right Bobby. I need to look at it that way. I know for sure what the problem is now. Just a little discouraged about it.

BTW - Love your avatar(s).

[MCRider]

I recently un-stuck a CB750 by putting a socket/breaker bar on the alternator nut. You have to remove the alternator cover to gain access (left side of engine, use oil catch pan underneath).

Joe,
I thought about doing this, but I was afraid of putting too much force on it and over-tightening the rotor bolt or breaking something. Is it strong enough?

he's speaking of the alternator rotor bolt, not the ignition drive, which is below the cover on the left hand side of the engine, as you sit on the bike.

It is quite beefy, if you can break it, you're a better man than I.