Please help with 79 KTM 250

[firebawlp]

I'm 20, love older bikes, and recently bought a 79 KTM 250.It ran great until yesterday. I parked it for about 5 minutes, and when I went back to start it, the kick starter would not move. I pulled the plug and tried, wouldn't move. I pulled the oil plug and tried, wouldn't move. I tried to get it to crank by coast-starting it, back wheel just locked right up. The only way I can get the kickstarter down is to hold in the clutch (which does nothing) but that's the only way to move it. PLEASE, PLEASE HELP. Thanks.

[tomale]

Sorry to hear about the bike, It could be alot of things that could cause this so we will need to start with the simple things first. What kind of 2 stroke oil did you use and how much per gallon of gas. Were you running it wide open alot before you shut it off? Does the kickstarter feel like it wants to move but something is preventing it from moving. Ie the piston has siezed and it will not turn over or does it feel like something broke and it locked in place.
Based on what you have described it sounds to me like you have siezed the piston. If this is the case then the top end will have to be taken apart and at the very least cleaned up. More than likely it will have to be taken apart and bored out and a new piston installed. If this is the case the rod bearing need to be looked at too to make sure that they were not damaged as well. what happens when a piston siezes is there is too much friction and the piston begings to leave score marks on the cylinder walls, pretty soon it get difficult for the piston to move up and down which only make for more damage. This happens fairly easy on a 100 or 125 but not so easaliy on a 250. The cause for this is usually there was not enough oil in the gas and or the wrong kind of oil was used, This can be made worse by running the bike wide open alot on a hot day especially with cheap oil. Heat is a real problem and so good quality oil and gas needs to be used if the bike is to run right for along time. Everyonce in awile you will hear of somebody getting a new bike, especially a 80cc or small bike and running it down the street wide open and then shutting it off only to not be able to get it to run again. I am not suggesting that is what happened with your bike but only bring it up to illustrate how easy it is to sieze up a small bike. The bike siezed because the bike did not have ample time to warm up and they used if at all either the wrong ratio of oil to gas or what ever oil was handy. Please do not be offended I only am trying to help. and will be more than willing to sift thru the situation to find out what really went wrong with your bike. I hope it is not too serious.

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[pketchum]

Try removing the spark plug, then the r/h side ignition cover.  Now see if you can move the crankshaft by putting a socket wrench on the clutch and turning it clockwise.  Does it move now?

My '80 KTM 250 project bike "stuck" once like this.  I thought it was because I'd removed the exhaust pipe and let it sit for about 2 months in enclosed storage.  However, with a slight amount of pursuasion with the socket wrench I discovered that the piston wasn't frozen in the bore at all.

Good luck,

Phil

[Bryan]

Could have gotten dirt or something in the motor and caused it to freeze up. I'm 23 and I like the old bikes to I'm helping my dad restore his '76 250 Penton he bought new back in '76 also he has a '78 400 KTM and a '73 Cz 250 and I ride a 2000 KTM 250sx.

Bryan