I own a 2007 270 beta, its done very little, I seems to run spot on one day then the next time I try it it seems to run weak on the mixture and start to knock now and again. Ive tried all sorts with the carb, different needle setting / mixture screw etc, Ive just fitted a brand new stator. Can anyone else help here? any idears as its driving me mad! Thanks Jonathan

The first thing to try is fuel try premium unleaded and

it has to be fairly fresh,low octane fuel or poor quality fuel

or stail fuel can cause these symptoms.

Its a few gallons of fuel through it, they have always come from the shell station were i live, im using 70mm of putoline protrial oil, Im getting to the point were a galon of fuel and a match might be the answer! Jonny

Better gas will stop a lot of beta knocking.

#27.5 pilot jet and needle second notch from top makes it run smooth.

Check the air screw is adjusted for best idle speed for the day (approx 1.5-2 turns out).

Check carb connections and gaskets for air leaks

Always run a clean and properly oiled air filter.

AND then put up with what is left. Ralph

The needle is on the middle clip, ive tried the mixture screw in and out a few times, been trying to keep it around 2 turns out, im goin to give it a good checkin over tomorrow, Jonathan

Gday, 1 1/4 to 1 1/2 turns is about right for Mikuni's on 2 strokes. 2 turns will lean the idle out a bit too much. ( This is an Air screw)

HTH,

Cheers,

Stork

Ive had the carb in bits a few times, absolutly spotless no water or dirt, Ive put the kill switch earth onto the main frame were the coil earth goes on, Ive got a feeling it might be suckin air in on the reed valve, Im goin to try and seal this it and try it this weekend, Fingers crossed, Jonathan