Seized Cylinder on a Suzuki GT550


Motorcycle Classics tech expert Keith Fellenstein
Editor's note: If you're having trouble with that old Suzuki, BSA, or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send your questions to: Keith's Garage, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with "Keith's Garage" as the subject.

Q: I have the chance to buy a reasonably nice Suzuki GT550. I believe it is a 1976 model — one of the later disc-brake bikes — but the center cylinder on this triple is seized and I wondered if you have any thoughts on the best way to free it up?
— Peter/via email

A: You can do a simple test to see if it is the piston seized in the bore (somewhat common and fixable) or a seized main bearing (unlikely, but probably a deal killer). If the seller will let you, take off the left side engine cover, and with the appropriate size wrench gently turn the nut at the end of the crankshaft back and forth. If there is some movement you can assume the main bearing is free. If it passes that test and you buy it, the next step will be to pull off the cylinder heads and have a look at the middle cylinder. If the piston is up you won't be able to tell much, but if it is down you should be able to see if the bore is scored or scuffed, indicating a seizure while running. If none of the transfer ports are visible yet there is some room in the cylinder to hold liquid, the shade tree mechanic fix is to pour in a mixture of ATF and acetone and let it sit. After a decent interval of several days, you can again try to turn the crankshaft with the wrench, looking to see if the center piston moves at all. If the center piston isn't at TDC you can also try tapping the center piston with a suitable sized wooden dowel and hammer. Easy does it. Repeat the solvent, wrench and tapping until you achieve success. Once it's free, you can confirm if you'll need a new piston or other work to get it running. Good luck!

6/14/2018 11:59:51 AM

A 50/50% mix? Thnx - -Chad

6/14/2018 11:58:40 AM

A 50/50% mix? Thnx - -Chad

6/14/2018 9:05:51 AM

ATF/Acetone mix free'd up very rusted piston in Honda FT500. I put it in 5th gear and "jogged" the rear wheel forward/back several times over a few days and suddenly it was free. Al

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