i cant find what this thing need alot of guys have tryed to help with no luck.its a 1993 Blaster with no silencer,a oil block off,new reeds,it starts ok and runs good up to 3/4 of throttle but 3/4 and more it just stops on me.is it running to rich or ? dynojet guys had me put a 360 jet in it because of the no silencer and the open k&n.and it did help some with the idle.so its idling good now but if i throttle it all the way it just boggs down on me. Any help will be great guys  thank all  

bogging down is a sign of the fuel mixture being too rich.

has the cylinder been bored?
if not then you really don't need a bigger jet.

you can factory jets with the silencer removed, but you'll need to adjust the fuel mixture via the fuel/air mixture screw.

the 310 jet sounds like a "Toomey" jet that is included in the blaster b1 exhaust system. which in my opinion is the best exhaust system around for the yamaha blaster.

i have installed many of these.
always a great purchase.

i would try the stock jets and tuning it in via the fuel/air screw.

you may need to go to one groove lower on the needle.
but i think stock will work better for you.

unless you are changing the silencer and the pipe you don't really change alot.
a little less back pressure, but the stock pipe still has a very small outlet.  

I dont know about the bored.I have tryed the small jets and play with the screw and it did the same with this one it did help the idle and some topend too.