Seized 250ES Engine....Any tips on how to free it up?

[BigRedRider85]

I purchased a 1986 Big Red parts bike....drove a couple hours away to pick it up, well before I left the guy never told me the engine was seized. Just wondering what to try to maybe free this thing up. The motor doesnt look bad, just stuck from setting for years. Thanks fellas

[atc007]

Simply start with Pb Blaster or any good penetrant. Honestly,,it usually doesn't take much at all. Some are gonna chastise you and tell you you will HAVE to tear it down... Almost always not the case. Let it sit overnight,and try it. Usually the kicker won't do it. Pop the access plug off the mag cover and put a 17 in there with a breaker bar or ratchet. Work it,,run it a little,drop the oil,,flush the engine and get a good oil in there and see what you have! May be junk,may run forever fine.

[honda4h]

check the crank case for oil if there's oil in it that's good. i had a 200s locked solid i filled the cyl with 10w30 sat for a week. worked the crank it had little play and it broke loose to my surprise the bike ran good and no smoke or noises after cleaning the carb.

[Badbmwbrad]

You can fill up the cylinder with diesel fuel and let it drain past the rings into the crankcase. You can keep adding diesel fuel through the sparkplug hole and it will act as a penetrating oil.

[Yamaha_Rules69]

It would be best to pull the head off. You could leave penetrant in there for a year, and it still may not free up, it all depends. Im 75% sure it would smoke if it does just free itself up, it will for sure have a rust ring in the cylinder, and the rings should be replaced and the cylinder be honed if you want a dependable machine. Besides that, the rubber O rings turn rock hard if not started in a long time, as well as the gaskets. I would just do a top end kit, and go from there. For penetrant to put in the cylinder, I have used coca cola before on a tractor, and it worked to free the stuck rings after a few days. There are also a lot better things than PB blaster, like Liquid Wrench, or Kroil are about twice as strong. You can also use a mixture of 50 percent power steering fluid, 50 percent acetone. Shake it up real good, and spray it in the spark plug hole. Its supposed to be the strongest penetrant known to man. If all else fails, pull the head, and use the good ol block of wood and heavy hammer, and pound that piston down.

[BigRedRider85]

Thanks guys for all the help...going to try to free it up tomor. Like I said it is just a parts bike but would really like to have this engine as a spare. I will let yall know what happens in a couples days.

[atc007]

My post is 100% from experience. It works. IF the engine is garbage or has water in it. Yes,,it will need to come down. Obviously,,,IF you are hoping to NOT tear it down.. You are not going to dump corrosives into an engine :)

[jeswinehart]

I agree 100% with 007, start simple (99.9% of the time it works just that easy). Whether you use penetrating oils to home made (I really like tranny fluid + diesel in a 50/50 mix ratio) the biggest key is let what ever do its work.
It took lord only knows how long to let mother natures loctite take hold (rust), so give what ever you use plenty of time to "soak in".

[kebby28]

I also agree with 007 except I always go to the parts store and get Marvel Mystery Oil. I have unsized many motors with that stuff so I know it works.