Poor running 2 stroke after storage

Hi. Picked up an 09 KTM 300 exc the other day. Has not been ridden for 6 months, and fuel appears to have been left on. Starts OK, and runs well at high revs, but runs rough under load and when flattened off at stable speed. I suspect the premix oil has settled and gummed up the carby. is this a remove the carby job, or is there an additive I can place in the tank to assist?

Please tell me it is not running on the gas that was left in the tank. Pull the plug on the bottom of the carb and shoot it with carb cleaner, both up the bowl and in the plug you removed. Replace the plug, turn on the gas and see what happens.

You need to drain gas and put in non ethanol fuel. Clean carb totally. Keep startron additive in your gas.

Thanks Fellas. I gather that you are saying I'll have to pull the carby appart Dwight? As of this arvo I've drained all the gas, put in fresh 95 octane juice with some fuel additive/carby cleaner. I also cleaned the airfilter as a precaution, although the onlt thing wrong with it was that it was dry as a nuns nasty. I'll take it for a fang tomorrow and see how it goes.

If it does not run perfect, do not push it hoping it will clean itself out.....you could create a dangerously lean situation.

I doubt this is the problem... On a Honda, could not get it to run right no matter what I did. Had been sitting in storage for over a year with ethanol gas, was running rough, so I cleaned the carb and all jets with guitar string peices.

Still wouldn't run right, no top end under load but would start and rev just fine.

Guess what... turned out mice had made a bed in the exhaust. Cleaned it out and BAM, it ran like new.

So, if you've "exhausted" all other avenues, check the exhaust, perhaps it's rusty and the spark arrestor is plugging it... or mice are (were, LOL) living in it.

Talk about a left fielder Sasqui! There is a mouse plague starting here, so I shouldnt rule anything out.

Went for a blast this morning with new juice etc. White hot performance at high revs, surging & farting down low. I recon I have a blocked jet. Suspect its a trip to the mechanic.

I'll keep you all posted "no pun intended"

I would take the carb off jet it change the gas and plug i always ran 32:1 in my 2 strokes also are you running a stoc

k pipe?

It is less then a dozen fasteners to pull the carb, 4 more to pull the bowl and a few bucks for a can of carb cleaner. Pull it out, clean it up and check you jetting. The dealer is going to wack you for an hour to do it.....it is worth the effort to try, you will need to know how anyways.

I agree with everyone else but if that still doesn't fix it, get new plug. That ended up being the culprit on my stored away bike

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now