1989 blaster w/ few mods jetting

[Blastermit]

I have a 1989 yamaha blaster thats bored .2 over with a weisco piston and boyeson power reeds stock expansion chamber aftermarket pipe dont know the brand sticker was burnt oil injection aftermarket airfilter no airbox lid tors unplugged i am currently running a 300 mainjet if i open it all the way up it will backfire and bog down no airleaks what size jet should i run thank you

 

[Larry's Shee]

are reeds new? Presuming you mean stock expansion chamber and A.M. silencer you should be about 250 main.
clean carb and float set?
search how to do a plug chop. That's only way to verify correct jetting.

 

[Blastermit]

are reeds new? Presuming you mean stock expansion chamber and A.M. silencer you should be about 250 main.
clean carb and float set?
search how to do a plug chop. That's only way to verify correct jetting.

Yes to everything but its an aftermarket silencer thank you also i have the tors disconnected if that changes anything