my brother runs a 110 revtech and a 40mm mikuni carb, Arlen ness Vstack, with&nbsp\\;martian brothers&nbsp\\;(daisy cutter)&nbsp\\;exhaust.&nbsp\\;\\\\\\; I have cleaned the carb 2x's it is spot less, put in new plugs, check the wires, check the coils, added baffels for better back pressure... it is all spot on and he keeps getting a backfire out of his carb when he comes off the throttle hard... any ideas? I am gong to try to set the needle back another clip and see if that helps if not i am thinking the accelorator pump is off...

[IMG]local://upfiles/26534/DED7398A199B4CC385F3A7C103B7EAFC.jpg[/IMG]

 

The needle is a mid range jet you need to up the size of the pilot jet...it's too lean.

 

Revtech delievers that motor with a Mikuni 45

 

This thread is old enough to hope that the problem is long gone by now.
Scott