hello again many thanks for the help with my evo 300 4t i have cleaned the connectors on the cdi and the connector block to get the green of and tried a new spark plug i have cleaned the jets in the carb and the bike is still spitting and banging and will not rev out properly but bike starts first kick and ticks over fine any more help would be great many thanks john

i had something similar on mine,which turnedout to be a blockage wher the fuel comes into the carb,you would have to remove the float and another bit behind this mine was really blocked so on more revs it's was in effect running out of fuel,so was cutting out then coming back in ,it would tick over all day.have a look as i know most won't take thi bit apart.

You might also like to try running the bike without the filler cap (but be careful!).

I had a problem with the valving inside the cap limiting the amount of fuel which could run out of the tank.

try moving youre neddle,mine was the same so was my mates.just cant mind whitch way ,sorry

Promise you won't laugh but I had a similar problem with my Rev 4. Turned out to be quite comical but presented in the same way. I allways put a rag in the airbox after removing the filter to clean it. This was to soak up any water that had got in from the jetwashing. One day I forgot to take it out, refitted the air filter and then halfway through a competition I had the same symptoms. The rag had sucked through and occluded the carb. Whole club laughed at me when I pulled the rag out. 4t engines can suck a lot through when you open them up. Could be worth checking the rubber from the airbox to the carb. I think it sounds like starvation rather than electrical.

many thanks to every one for your help with my beta 300 i have done the things that you have suggested and the bike is running a lot better the problem is now more intermitent now i went up the road on it and it ran fine when i got back it started to back fire and spit again i noticed that the inline fuel fillter was not full so i cleaned out the petrol tap but still back firing and spitting with a bit of a flat spot i will keep on trying other things

hello everybody out there still having trouble with my evo 300 4t still spitting and banging and flames out of the exhaust dried out the cdi box and cleaned the terminals checked all the inlet pipes from the air box to the carb taken the carb of and cleaned all the jets and were the fuel comes in new spark plug checked the fuel tap all clean at a loss to what it could be may need a new cdi box or stator but bike only just over 2 years old any more help would be appreciated many thanks john

Edited March 15, 201313 yr by johns workers

Topic moved and merged with previous. One problem, one topic please. That makes it easier for people who are trying to help to see what had previously been said/done.

hello every one out there still having trouble with my beta evo 300 4t still spitting and banging and flames out of the back box tried new plug cheked the air hoses from the air box to the carb the one on the air box was off put it back on still the same cleaned the jets in the carb and the fuel inlet valve removed the fuel tap all clean dried out the cdi unit and cleaned the green of the terminals and the connector block at a bit of a loss were to go next any help would be appreciated many thanks john

I had a similar problem (endless splitting and banging) with my 2009 4T. In the end it turned out to be dirt in carb. I checked everything but it was not until I cleaned the whole carb seveal times the problem disappered. I don´t think that just blowing the jets will be sufficient. All drillings in carb must be cleaned with clean compressed air. Nowadays I put an extra filter just before the airgun when cleaning a carb. So there are two filters in the air line, one just after the compressor and one before the gun.

hello there i think you could be right about dirt in the carb as i have cleaned the carb again and i rode the bike and it does run a lot better now many thanks for your help and everyone else who helped with my problem

hello every one out there still having trouble with my beta evo 300 4t still spitting and banging and flames out of the back box tried new plug cheked the air hoses from the air box to the carb the one on the air box was off put it back on still the same cleaned the jets in the carb and the fuel inlet valve removed the fuel tap all clean dried out the cdi unit and cleaned the green of the terminals and the connector block at a bit of a loss were to go next any help would be appreciated many thanks john

When was the last time the valves where checked?