1980 Rm250 Won't Start!

Had it sat for some time before you got it? I wonder if the exhaust could be plugged? The smoke in the cylinder says you are getting some kind of heat. The other thing that comes to mind is significant timing issue. Do you know the last time it ran?

It can spark outside the engine in normal air pressure but not spark inside the engine because the higher the air pressure the higher the voltage needs to be to create a spark. Some old flywheels lose magnetic strength which lowers voltage to the CDI. Also any rust at any electrical connection of the ignition system (sometimes even a screw holding down the stator plate) can act as a resistor and lower system power. But if you lower the compression with an extra head gasket and bump start it going fairly fast (two people pushing hard) it should start but then die if you let the revs get too low. Only real solution then is to change the magnetic flywheel.

BarterFreak- 116 said:

I just got a 1980 RM250 today. This is the second 2 stroke I have gotten and I have had 4 strokes too. This one is puzzling me. I have compression, air, new gas, new oil, new plugs with a blue spark, just cleaned the cylinder and it will still not start or even want to start. I just tried to bump start it a bunch of times, but still nothing. Every time I kick it and then take out the spark plug, white smoke comes out. And I tried putting gas into the spark plug hole. I have no idea what is wrong, I have everything that is needed to start an engine. Please Help.
Thanks

Click to expand...

Check the heat range of the plug, is anything like a rag in the intake tract? Right octane in the fuel? Needle valve sticking? Flooding out? Kill switch issues? Bad gas grade? Too much oil in the fuel? Clogged fuel filter? Clogged exhaust system? Get a manual and get to getting....