MZ ETZ 250 won't start

[nathan]

Hi im 18,
I own a 1988 MZ ETZ 250. This bike was running fine until I decided to hoon around the paddock with the exhaust off.(I am regretting it now) The bike doesn't kick over and I'm wondering if anyone can give me some ideas of how to fix it. I have spark, fuel running into the carby and Iv'e got a new battery. If it's engine problems where should I start. Any help would be great. thanks

[Old Dog]

When you say it won't kickover, what exactly do you mean?
Are you saying that the kickstarter is locked or that it kicks over but won't start?
If it is locked it is probably a nip up, start by taking off the head and having a look down the bore

The problem with 2Ts is they are mechanically simple but the physics is complicated they rely on resonance to effect proper gas flow...

[DAVID THOMPSON]

bad idea to take a buzz on any bike with the exhaust pipe off
it can do the piston in in a hurry some times
dave

[mr_luke]

As well as things like gas resonance, etc., the exhaust plays a big part in removing heat from any engine, and it does sound as though you've probably seized it. Having said that, you say you've got a spark, so perhaps we're reading your post wrong as I can't see how you'd have a spark if you can't turn the engine over..?

What do you actually have the bike for? Transport, or general abuse/playing with off road? The answer might affect how you go about "fixing" it...! Either way, as has already been said, I'd take the head off and have a look!

[nathan]

The kick works fine. When I say it wont kick over I mean that when I do kick it the sound it makes is quite strange, it makes a 'poof' like sound, you can hear it coming from the exhaust and it may make the occasional backfire. Then there is a strong smell of fumes. I hope that makes sense.

[nathan]

Is it possible to post videos?

[Agronski]

If you are very lucky, you've just killed your piston rings and the fuel is blowing past your cylinder and coming straight out your exhaust port - hence the smell of 'fumes'.

If you are less lucky, running without an exhaust has caused a lot of detonation and you've burned a hole in your piston.

Either way, take the head and cylinder off and post a picture of the piston and bore...and don't ever run without an exhaust again. With 2-strokes, the exhaust is part of the engine, not just a passive tube.
___

[nathan]

Thanks for the advice, I'll take it off and post some photos. Will I need new gaskets when taking it off and what is a good site to get parts from.
Nathan

[nathan]

Piston is fine, just a bit of carbon build up.