Engine locked up! next step?

[Guest]

I am still trying to get my '78 gs750 to turn over. I have had Deep Creep in the cylinders for over a week. I have rocked the bike back and forth in gear, tried the kickstarter, and recently tried to turn the bolt under the cover by the points. I am doing this in neutral (the neutral light is on). I am afraid to reef on that bolt, but it seems that I need to somehow knock the pistons loose. Can I use my impact driver on that bolt? Does it matter which way I rotate the bolt? If that doesn't work, I think the next step would be getting the head off and maybe trying to persuade the pistons directly with a wooden block and a mallet. The PO swears that the engine ran fine until he quit riding it. Any thoughts on a plan of attack?

[JEEPRUSTY]

I am still trying to get my '78 gs750 to turn over. I have had Deep Creep in the cylinders for over a week. I have rocked the bike back and forth in gear, tried the kickstarter, and recently tried to turn the bolt under the cover by the points. I am doing this in neutral (the neutral light is on). I am afraid to reef on that bolt, but it seems that I need to somehow knock the pistons loose. Can I use my impact driver on that bolt? Does it matter which way I rotate the bolt? If that doesn't work, I think the next step would be getting the head off and maybe trying to persuade the pistons directly with a wooden block and a mallet. The PO swears that the engine ran fine until he quit riding it. Any thoughts on a plan of attack?

DO NOT USE THE IMPACT DRIVER!

You say deep creep for over a week. Dies that mean you put it in everyday or several times a day? Can you fill the cylinders with it, and if so, does the stuff drain away quickly or not at all?

Acetone is a favourite chemical of mine it disolves most anything. Try that in you cylinders.


If bruet force is what you need then put it third gear and coast down a hill slowly engaging the clutch.
no impact drive that rotor is secured in small thread and the keyway is not too robust either.

[Steve]

"Ran when parked" ... classic line.

How long ago?

If the engine is locked up THAT solidly, you will have to resign yourself to taking it apart, but be forewarned: it won't be pretty.

Unless you have something special about that engine, it will be esier, faster and cheaper to just get a replacement engine.

.

[tkent02]

Perfect! Now you can throw an 850 top end on it and be done.

[Nessism]

Time to pull the top end.

[snyderman]

I have no fear about pulling the top end, just wondering how to go about it. I should be able to take the head off, I just wonder about separating the cam chain, does it have a master link that I wont be able to access? Once I get the head off, is there a good method for freeing up the pistons directly? I figure that even if this engine is junk, the further I go with it, the more I will learn. I am not in a hurry to ride, I wanted a project.

[JEEPRUSTY]

OEM cam chains have no master link. Well mine doesn't and all the engine rebuilders on here eschew them.

Take some pics and share them.

[Ranger]

Hope you have better luck than I did.

Its not too hard to do, just takes time but quit forcing anything.

[tkent02]

You don't have to remove the chain, just remove the cam chain tensioner, slide the cams out from under the chain and drop the chain into the hole, then off come the head and the cylinders. You can fish it out later, or tie it to something so it doesn't drop down in there if you'd rather do that.

[snyderman]

Thanks for the tip on the cam chain, makes perfect sense. How about freeing up the pistons? Is Hitting a wood block or dowel placed against the piston a good idea? is there a better way? Thanks for all the help! I love this forum!

[tkent02]

Other than soaking it in a 50/50 mixture of acetone and ATF for a few weeks, I don't have any ideas.

[Nessism]

With the head off you can then work to get the cylinder block loose from the crankcase. They like to stick pretty tight sometimes so work carefully or some of the fins can be knocked off. Once you get the cylinder loose you should be able to figure out which cylinder(s) are sticking. Using your hammer, handle end down on the pistons, should help persuade them free. If that doesn't work, I'd soak them more and consider using a heat gun as well, but don't force anything too much.

[tkent02]

Ed, how hot did it have to be to remove the liners from the cylinders?

[snyderman]

Thanks again! It sounds like the soaking can take longer than I thought. As long as it makes sense I'll keep soaking and waiting after I get the head off, if gentle persuasion doesn't do it. One more question The mix of acetone and ATF, what is the ATF?

[cowboyup3371]

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