GS450 motor siezed - suggestions on breaking free

[byrdman76]

Picked up a GS450 the other day that the motor is locked up in. The bike is in great shape and was garage kept.

The P/O removed the carbs to rebuild them due to the bike running rough. he said it took 2 or 3 months to get the bike back in order due to other obligations. He realized the motor wouldn't turn over when he got everything back together so he removed the starter and took it to the dealer where they informed him that the starter had failed and sold him a new one.

I had hoped that the issue was the motor was hydro locked or the starter wasnt installed correctly. Unfortunately it was neither. I have torn the bike down to the cylinders and bottom end. Head is removed including the stator and starter, carbs and exhaust. The cylinder walls look clean and i can still see the honing marks in the cylinder wall. The bike is locked up so that the cylinders are just below TDC on piston 2 and right above BDC and piston 1. The exhaust on cylinder 2 was white but the rest of the entire motor looks fine.

Ive had the bike sitting with PB blaster for 24 hours but i still cant get it to budge with a wrench on the crank or in 5th gear turning the wheel by hand. Ive even tried tapping on cylinder 2 with a rubber dead blow while trying to turn the motor over. The crowns on these pistons seem thin so I didn't go too crazy.

My question is how to break it loose and what I might damage while Im doing it if i get a little more forceful. I'm wanting to sit on the bike in 5th gear and try to rock it back and forth but I'm scared I might bend a rod or damage something else.

Could it be something else that I'm missing??? The bike rolls freely in neutral, and the clutch was very stiff but seemed to slightly function.

Any suggestions [-o<...

Thanks,

Byrd

[Nessism]

Seems strange. If you can pry up enough to break loose the cylinder base gasket you should be able to figure out which piston is stuck. At least then you can focus your efforts on one side. Only other thing that pops into my mind is that something has droped down into the bottom end keeping the crank from turning.

Sorry but can't think of anything else to suggest.

[Ironriot]

Maybe the PO overrevved it and spit a rod. That's the only thing I can think of that would cause it to be siezed so bad. I know it would be alot of extra work but why not just split the cases?

[TheCafeKid]

That may be the only way you find out for sure what is going on in there.

[49er]

Does your engine have a removable sump cover? If so, remove it so you can do a visual check of the condition of the crank, con rods and the timing chain sprocket. As mentioned above, there may be something down there preventing the crank from turning. There could also be small lumps of molten aluminium down there!
If #2 exhaust is white, that pot has been running too lean. If you look at that piston crown, does it look ash coloured, particularly on the outer edge around the top ring? If so,the top end has seized.

[Matchless]

Have you taken the alternator side cover off yet?
Just a thought when I tighten the flywheel/rotor bolt I usually put a copper coin in the teeth of the large gear on the flywheel to the starter gear to stop the engine from turning.
You may have something in there , like in the starter gear teeth of even your stator magnet jammed on the stator by parts from the starter clutch. I suggest having a good look here.
Good luck

[gaillarry]

I had an old XS750 triple that was seized. Removed the spark plugs, soaked the cylinders with marvel mystery oil. Then hooked a tow rope to the bike and towed with my truck about a block, then let the clutch out. It came unsiezed quick. Sprayed oil all over the bike and me, but it came back to life.

[Ironriot]

I had an old XS750 triple that was seized. Removed the spark plugs, soaked the cylinders with marvel mystery oil. Then hooked a tow rope to the bike and towed with my truck about a block, then let the clutch out. It came unsiezed quick. Sprayed oil all over the bike and me, but it came back to life.

Awesome, now that's what I'm talking about

[49er]

I had an old XS750 triple that was seized. Removed the spark plugs, soaked the cylinders with marvel mystery oil. Then hooked a tow rope to the bike and towed with my truck about a block, then let the clutch out. It came unsiezed quick. Sprayed oil all over the bike and me, but it came back to life.

If you tow the bike and something is jamming the crank or its auxiliaries, you will break something. Should you still decide to tow it, don't tie the rope to the bike, hold it in your hand. If it's tied, you can't release it quickly in an emergency! Holding it is ackward, but much safer.

[psyguy]

I had an old XS750 triple that was seized. Removed the spark plugs, soaked the cylinders with marvel mystery oil. Then hooked a tow rope to the bike and towed with my truck about a block, then let the clutch out. It came unsiezed quick. Sprayed oil all over the bike and me, but it came back to life.

imagine the reason for seizure wasn't stuck pistons/cylinders but ... say ... damaged cranckshaft ...
your method would have been even more funny !!! :-\"

[byrdman76]

Got It Free - Yessss!!!!!!

The issue wasn't with the pistons... The P/O had some how gotten the timing chain wedged to bind the crank. He most hove done this when he removed the carbs and the cam chain adjuster.

The motor turns over free as silk and the cylinder walls look great. I filled the cylinders with 10-40 and turned the motor over repeatedly to ensure.

I removed the clutch assembly and was able to get a large wrench on the crank. I reversed direction of the motor and pulled on the cam chain at the same time. Popped the motor right loose \\/.

Glad i didn't go crazy trying to push start it.

So there it sits until I get done with the 550. I just couldn't stand not knowing what was wrong with it:grin:

I'll keep you posted...

Thanks for everyones help and suggestions!

[TheCafeKid]

Great news BM! I always loved a happy ending *sniff sniff*

[SqDancerLynn1]

If you do push it make sure to tie the cam chain up so it can turn without jaming too!