Need help jetting

[MTDman11]

ok heres the deal, i have a hmf sport series slip-on, white brothers e-series head pipe and a K&N air filter. its backfiring on deceleration and my dads friend said its because its 2 rich cause there is all that extra gas in the motor and it has notin to do with it so it backfires. what adjustments to the carb do u guys recommend.

more questions:

whats the compression ratio of a stock 300ex

is the carb a kerhin(yes im pretty sure)

is the carb a flat side or a round carb.

[SET THE STAGE]

your dad's friend couldn't be any more wrong. it's backfiring on decel because you're running LEAN. try maybe moving the clip on your needle down one and a size higher in your main jet to richen it up a bit.

stock ratio is like 8.9:1 or something ridiculously low, i believe. don't quote me on that exactly

the stock carb is a round-slide keihin carb.

[MTDman11]

k thanks, any more help is appriciated