two stroke 250 wont start, please help!!!

[johnkbl]

Hello!

I am having problems starting my KTM 250 two strokes, 2003.

Bought the bike a couple of years ago and used it a few times. I had to kick start the bike once a week, otherwise it wont start after two or three weeks. Due to my job, had to travel a couple of months and when came back, it never started again.

Two days ago I was able to start it 2 or 3 times with carb cleaner, and it ran without gas for 5 or 10 seconds each time, until the carb cleaner was burned. After that, I poured some gasoline and nothing.

Took the carb out and it was dirty. Not that much, but there was something like a mass of oil un a screw that is in the bottom of the float reservoir. Cleaned it troughly. the float is working fine, checked all the small holes and unclogged everything. Put back the carburator, kicked it and nothing.

The spark plug is working, it has a small spark, but it is there. I will check compressions today.

The oil smells like gas. I will change it once I can make the engine start.

Questions:
Could I have damaged the cylinder by kickstarting the bike with carb cleaner? it was only a few seconds every time, but... is that a possibility?

What should be the value of the compressions in order to determine that I need to replace piston and rings?

Is there something else that I can check? What else can I do to troubleshoot the carb?

Thanks!!!

[KTMfreek]

To me if it starts on Carb cleaner then it is a fuel issue. If it were me I would dump the fuel out and put in fresh fuel/ oil mix, take apart the carb and soak it in an Gallon of carb cleaner ( looks like a normal paint can but it has a basket in it so you don't lose your parts.) I am guessing you have some varnish that you can't that is blocking the fuel flow. Get a new spark plug put it back together, change the oil in the crank case! If everything is good it should start up within a few kicks.

About using carb cleaner spray - If I run into a bike that won't start and I don't know why... I will use a squirt of carb cleaner to see if it will run but no more than that. If it doesn't run I know that i have another problem. My two cents

[johnkbl]

forgot to mention that after the 3 starts with carb cleaner, I poured more gas in the carb, kicked it, but nothing. Then, I cleaned the carb and tried to start it again with carb cleaner and the bike did not start. That's why I am asking if the bike could have suffered some damage due to starting it with carb cleaner.

[KTMfreek]

When you poured gas in it probably got the plug too wet. No it is not recommened to run a engine on carb cleaner but for that short of a time I would guess that you are still ok.

[bajadog]

Like freek said carb cleaner should not damage an engine...

Starting fluid (ether)..now that will.

[Jason380mxc]

My thought is you are fine with starting engine BRIELY with carb cleaner, starting fluid whatever, but remember there is no lube in those fuels.

[johnkbl]

Well..

Thanks all for the help. I have found that there are several types of carb cleaner. Those for two strokes have lubricant, and wont damage the engine. The one I used has no lubricant, but the engine is working fine.

I checked the compressions, it has 125psi. It will need a top end rebuild in a few rides. Replaced the old gas with new one and flushed the engine twice. The old oil was extremely dirty, and even the second flush was still a bit dirty.

The bike now is working. Effectively, the spark plug was wet after I reinstalled the carb. Checking and checking... I found that the gap of the spark plug was about 2milimeters, while the specs is 0.60 milimeters. After closing the gap, the bike started at the first kick.

Unfortunately, I had to spend a lot of time and money finding this by my self, but now I have a better knowledge about the bike and will be more prepared in case I use it for long offroad rides.

Thanks guys for the help.

[KTMfreek]

That's great that you got it going! Good for you!

With your compression being 125psi... when you do a put a new top end on it.. you are going to say holy smokes I should have done this along time ago!!

[Silverslug]

Check for broken reeds. I was told carb cleaner will damage the reeds.