Total Motorcycle Community Forums

K6 750 w/ M4 slip on
http://www.joshz.ca/tim/m4_shooting_flames2.mov

the M4 is looking even sweeter than i already thin it is...

question... i hear my exhaust backfiring sometimes. does it mean it also shoots flames visible at night?

what exactly is the concept behind backfiring? all i remember is it happens when im easing off the throttle sometimes.

Backfiring at decel means a lean condition. Try adjusting the fuel mixture screw out 3 turns.

Like this??



PS: I've seen some bikes at night pop, they do sometimes have a little blue light at the tip. Nothing major.

well yeah... but that M4 shoots pure blue flame. that's way more impressive than red flame.

CORSCO wrote:Backfiring at decel means a lean condition. Try adjusting the fuel mixture screw out 3 turns.

ooohhh running lean condition... thanks.


now, errr... what does "lean condition" mean again?

Anyone want to comment on whether this 'condition' is harmful to the bike in any way?

I guess the bike in question is fuel injected, my bad. If the pipe is anything like the aftermarket pipe for the R6, it is nothing more than a tube.

Maybe recommend buying a Power Commander for it so you can get the exact map you need for the pipe. Should help on the lean condition.

Lean is too much air to fuel. You have killed the back pressure and have installed a free flowing muffler.

Running lean on the overrun (throttle off) shouldn't be an issue at all unless it's excessive and blows out your muffler packing. If it's just a little cough or pop occasionally, then it's a non issue. If you start running lean under power though, then that is a problem. It can raise the exhaust gas temperature to the point where it will melt valves and put holes in pistons.

Verm - I'm not sure if you were kidding, but in case you weren't, a "lean" condition is when there is not enough fuel in the cylinder to use up all the oxygen during combustion. If you have more fuel and not enough oxygen, it's running rich. If you have the right ratio (14.7 to 1 by weight), it's a stoichiometric mixture. Typically for best power you want to run a little rich, and for best fuel economy a little lean, though there are other side effects of both.

Posthumane wrote:Running lean on the overrun (throttle off) shouldn't be an issue at all unless it's excessive and blows out your muffler packing. If it's just a little cough or pop occasionally, then it's a non issue. If you start running lean under power though, then that is a problem. It can raise the exhaust gas temperature to the point where it will melt valves and put holes in pistons.

Verm - I'm not sure if you were kidding, but in case you weren't, a "lean" condition is when there is not enough fuel in the cylinder to use up all the oxygen during combustion. If you have more fuel and not enough oxygen, it's running rich. If you have the right ratio (14.7 to 1 by weight), it's a stoichiometric mixture. Typically for best power you want to run a little rich, and for best fuel economy a little lean, though there are other side effects of both.

thanks for the explanation.

and yeah, it doesn't backfire constantly on mine so i guess that's normal.