80 GS450 Engine Stuck

[katoranger]

I just bought a 1980 GS450S that has been sitting in a barn since 1989. It is in great shape with 10K miles, but the I think the engine seized from sitting in the humidity.

What is the best method to free it?

Thanks, Allen

[KGB]

Pull the plugs out and spray some marvel mystery oil into the cylinders.
let it sit for a day or 3.

Keep the plugs out, put it in 2 or 3 gear.
try moving the rear tire. Don't put a breaker bar into the wheel and force it. This could damage the wheel , which will now cost more to to replace..Keep trying eventually it should allow the engine to turn over.

then you get to rebuild the carbs from the corrosion and glazing from the fuel left in them. and clean the tank and ..........well you get the idea.
It can be done with patience, don't get frustrated.

[katoranger]

Thanks for the response. The marvel oil has worked in the past. I am not in a hurry to damage anything. I am sure the carbs need help. They are not stuck at least the throttle moves. The transmission shifts.

I will probably need help with the carbs.

It was dark in the barn and I couldn't see in the tank very well, but it look pretty clean. The petcock moved.

The bike needs a master cylinder and a front signal lense, new tires and a battery and I think it will be a runner.

Allen

[mhardig]

I have a GS450 engine (also, I believe, seized) that I am cannibalizing for parts. If you want or need anything off this let me know. THe carbs are intact, and I'm gonna pull off the side covers and polish them and put them on my GS-450t. That's the plan, anyway.

[Dark Jedi]

I have used 3-in-1 oil to great effect as well. Half a can down each cylindar, and let it set for a long while. Then break free in 2nd or 3rd gear.

Marvel is also good, I just found to my preference, 3-in-1 penetrates better.

In either case, ya gotta clean out the crankcase, oil, filter, etc. Figured you knew not to run ancient oil anyway, but thought I'd add that for the people who find this thread later on.....

[katoranger]

Yeah, I plan to change the oil with I get it free. I just got it home Friday night and put some Marvel oil in both cylinders yesterday morning. I will give it a try every day until it comes free, until then I have plenty of other things to work on.

Thanks, Allen

[katoranger]

The engine broke free today. I am letting it soak some more though. I guess the next step is the carbs.

Thanks for the help.

Allen

[Billy Ricks]

The engine broke free today. I am letting it soak some more though. I guess the next step is the carbs.

Thanks for the help.

Allen

You definitely need to go through the carbs. Get it running and do a couple of oil changes to get rid of any corrosive bits that get broken loose.

[brveagle]

Make sure you flush the brake lines also... They should be nice and full with water and have very little stopping power left in them...

[Billy Ricks]

Make sure you flush the brake lines also... They should be nice and full with water and have very little stopping power left in them...

Good advice. The calipers and master cylinder could probably stand a close look at the internals as well.

[katoranger]

The master is shot and everything is froze up there. I am bidding on a working unit on ebay right now. I will then flush and bleed that unit along with new pads.

I bought a filter and some cheap oil to run in it for a 50 miles or so.

The carbs will need work, but everything moves except the choke. I have never taken motorcycle carbs apart before. I plan to pull them off and soak them too. I will probably just go ahead and get carb kits and o-rings.

Thanks for the tips.

Allen

[austinringding]

how exactly did you get the engine free? did you use the back wheel as someone suggested? i've got an '81 GS550L that is seized up and would really like to get it running.

i drained the oil and put marvel mystery oil in each cylinder and put it up on it's kickstand but moving the wheel doesn't seem to do it. also, the oil that I poured in doesn't drain out the bottom plug.

what to do now?

[Billy Ricks]

how exactly did you get the engine free? did you use the back wheel as someone suggested? i've got an '81 GS550L that is seized up and would really like to get it running.

i drained the oil and put marvel mystery oil in each cylinder and put it up on it's kickstand but moving the wheel doesn't seem to do it. also, the oil that I poured in doesn't drain out the bottom plug.

what to do now?

Eventually it should break free unless it's really screwed. Try pouring a little diesel or kerosene into each cylinder to thin the oil enough so it can make it past the rings.

[jimcor]

If it will not eventually seep thru, use a mighty vac or electric oil change pump to pump out the MMO ( :-D or you can just pick the bike up, turn it upside down and let it drain :-D ). Then fill back up with white vinegar. Really, read this in Classic Bike. The acidic vinegar will help disolve the corrosion. If the engine is in this condition a tear down for cleaning/restoration will probably be neccessary.

[katoranger]

It took about 3 days for the MMO to work and I had the bike in 2nd gear and turned the rear wheel. It may take a week depending on the level of corrosion. Make sure you have the sparkplugs out.

Also the oil will take a long time to seep past the rings before it reaches the bottom of the crankcase.

Allen