just rebuilt the motor and ran fine for a while.
now after getting warm it will revup all the way and not go down until you choke and kill it.
it also started backfiring quite often.
i checked the needle and seat and seems to b sealing

what else could b happening

 

Carb slide sticking? Also did you replace crank seals?

 

the same thing happened to my express 300 and i just changed the crank seals and then after that it worked fine

 

i did replace the crank seals when i rebuilt the moter
and slide is free first thing i checked.
when it the seals or reeds they say that it raps out consistantly.
idk
but
it backfirse bad and done it since done the motor and constantly gets worse.

 

if the engine is sucking air say from a bad crank seal it will do what you described. not the safest thing to do but if you sprayed starting fluid or maybe carb cleaner would work as well down around the crank seal w/ the engine running and if it idles up then the seal is bad. imo.

 

ok
ill try that and see what happens