Ok, I have a 300ex with a FMF Power Core IV system. I don't really know how much power a 300ex should have, because I'm not the origional owner. The power isn't real good. I think if I re-jet the carb it would help.

When I get on it, and shift through all gears, and then back off it always responds with a lot of quick-quiet backfires. Does this mean I'm rich, lean???

 

sound like a little rich to me, have you check the plug to see how dark the plug is?

Doe it run great at the top or little rough? Just asking.....
I have the 300ex and it took awhile to jet the bike of supertrapp IDS.

 

Backfiring, in and of itself, doesn't necessarily indicate a lean or fat condition, Most any performance pipe or silencer will cause the engine to backfire to a certain degree especially if the throttle is closed quickly. My unscientific opinion is because quickly closing the throttle causes unburned fuel to be exhausted into the pipe & silencer, where it is fired in the form of a backfire, hence the name.[img]i/expressions/face-icon-small-tongue.gif[/img]. Both my Warrior and Raptor have backfired under these circumstances. The Warrior did it for the 4 years I had it and the jetting was perfect. If you have not done a test ride & plug read with the after market pipe, then you certainly are flying blind in terms of whether the engine is lean, fat, or properly jetted. To eliminate this guessing game, do a proper test ride/plug read and see what your engine tells you via the plug read.
If you're unsure exactly how to do this, you may email me for my tutorial on both subjects.

 

<<<Double posts>>>> SORRY

 

<< Ok, I have a 300ex with a FMF Power Core IV system. I don't really know how much power a 300ex should have, because I'm not the origional owner. The power isn't real good. I think if I re-jet the carb it would help.

When I get on it, and shift through all gears, and then back off it always responds with a lot of quick-quiet backfires. Does this mean I'm rich, lean??? >>



Timing is bad! Need to re-shoot the timing, thats why lack of power too [img]i/expressions/face-icon-small-smile.gif[/img]


Ron