What should i use for a locked up engine?? Please help

Ive never owned a motorcycle before but im very mecanically inclined thats how i got this bike by fixing a car for this old man. Its a 1975 Yamaha rd 200 street bike 2 stroke with 6100 miles on it.Its been in a barn since 1983 and the rings are seized on it .Any of you guys have any tricks or suggestion for me to try.

Oh boy, a brave soul is awakening an old RD-200! First you need to find out if the engine siezed or if it is simply stuck. Cylinder scoring will be a very obvious tattle tale to oil starvation. If the cylinders are clean of heavy galling (scoring) you can try soaking the piston/cylinder interface with a penetrating oil, such as WD40 or the like. After a bit, you can try to carefully tap on the higher piston with a plastic hammer or a wood block. If you get any movement, apply more buster and try to reverse direction by striking the other piston. Work them carefully until they stroke fully. As soon as you can, apply some 2-stroke oil to the cylinder walls and work the engine over by hand until it feels fairly free. But, If you do the above and nothing happens - as if you are tapping on a piece of immobile metal, stop and dig a bit further to be sure you don't have a stuck lower end or primary chain or even clutch/transmission issue. I once unstuck an old bike, when I was a kid, by running alongside with it in neutral, then jumping on and dropping it into gear. It broke free, but it wasn't worth much by the time I lit it off (no compression) GOOD LUCK! Remember to mix your oil with gas until you are sure the oil injection still works.

thanks for the information,Ill try it when I get a break from working on a couple cars I have to get fix for some peaple.I had the same problem with a yamaha 250 2 stroke that I had bought off a childhood friend the engine was on the back of a gocart .I took the jugs off to fix it though, thats what Im tring to avoid on this one. I still have that engine its around late 60's model the one thing that I cant figure out on the 250 that I have is that the kick start is on the left and the chain sprocket is on the right side of the engine .I havent a clue what kind of yamaha it came off of.

First you need to determine why the engine is frozen, it may just be from sitting, or it may have greanded at sometime in the past and parked. Being a two stroke it's pretty easy to work on. First pull the heads and have a look, it what you see looks normal use a some from on penetrating oil, I like P.B. Blaster these days, squirt it down and let it sit for a few days, then try see if you can get it to break free. Once you have that pull the barrels and have a good close look, change the rings out ans hone the barrels before you put it back together.

Also check the reeds and transfer (crank case) seals, clean everything out and try to get it to come alive. Be certain that the injection pump is working, I might mix oil directly with the gas at a 50:1 ratio when you first start it to check tat the oil pump is working.

If you find it's a mess (holed/burned piston or seizure) you know what to do...

John.