Redhotrod
04-10-2009, 06:33 AM
I am in the middle of trying to jet my 300ex with a 400ex carb,
I just bought the bike, 1997 300ex, it had a dynojet jet kit in the original 300 carb, but it fouled the plug out at WOT. So I figured to keep up with my buddies with 400+ccs I would get a bigger carb at least for mine, My bike does have a full White bros exhaust, and I am running with my air box lid off with a pair of pantyhose overtop of the air box with a K&N filter with outerwear and the motor has been bored out recently, I just don't exactly know how much.
My problem is I cannot get the jetting right. with either carb. I kinda understand the concept, but I guess I cannot exactly tell the difference of a lean or rich condition,seems the plugs are lieing to me.
with the 400 carb, I have the stock pilot(38) air screw 2.25 out and the needle in the 3rd groove down, it idles great, plug looks brand new with it idleing for 5 minutes,
coming up to 3/4 throttle it has a little popping on the top end tried moving the clip up and down but the best I seem to get is at the 4th groove down
I have a handfull of main jets, running with the stock 400ex 148 main jet, it was fouling plugs, not sure if its cuz of not knowing if my needle is wrong or not. I have been playing around with the bike on a stand and in neutral revving it up to check jetting, will this work? or must the bike be under load?
So with the plugs fouling out I got a bunch of jets, the smallest I have is a keihin 135 and have been trying to get the plug right with that, I can't imagine needing a smaller main for the setup I have. Even with the 135 in I still have the same popping (like a rev limiter miss) with the plug turning brown/black
another weird thing is I will even pull the rear air boot off of the carb to help lean it out more and I notice at 1/2 throttle the carb is spitting gas back towards the air filter ?
anyone have any suggestions? I would love to get it running right, heading to the hills of WV in a couple weeks
I just bought the bike, 1997 300ex, it had a dynojet jet kit in the original 300 carb, but it fouled the plug out at WOT. So I figured to keep up with my buddies with 400+ccs I would get a bigger carb at least for mine, My bike does have a full White bros exhaust, and I am running with my air box lid off with a pair of pantyhose overtop of the air box with a K&N filter with outerwear and the motor has been bored out recently, I just don't exactly know how much.
My problem is I cannot get the jetting right. with either carb. I kinda understand the concept, but I guess I cannot exactly tell the difference of a lean or rich condition,seems the plugs are lieing to me.
with the 400 carb, I have the stock pilot(38) air screw 2.25 out and the needle in the 3rd groove down, it idles great, plug looks brand new with it idleing for 5 minutes,
coming up to 3/4 throttle it has a little popping on the top end tried moving the clip up and down but the best I seem to get is at the 4th groove down
I have a handfull of main jets, running with the stock 400ex 148 main jet, it was fouling plugs, not sure if its cuz of not knowing if my needle is wrong or not. I have been playing around with the bike on a stand and in neutral revving it up to check jetting, will this work? or must the bike be under load?
So with the plugs fouling out I got a bunch of jets, the smallest I have is a keihin 135 and have been trying to get the plug right with that, I can't imagine needing a smaller main for the setup I have. Even with the 135 in I still have the same popping (like a rev limiter miss) with the plug turning brown/black
another weird thing is I will even pull the rear air boot off of the carb to help lean it out more and I notice at 1/2 throttle the carb is spitting gas back towards the air filter ?
anyone have any suggestions? I would love to get it running right, heading to the hills of WV in a couple weeks