Latest problem need help

[DirtDiggler]

I have a white bros e series slip on and a uni filter. I use an outwear cover on the airbox and run a 155 main and 40 pilot. Befor the rejet I got a lot of let off backfire/popping. The quad ran like a bear for a couple of days until yesterday. It started out running good with little to almost no popping when I let off. Then after riding it like a madman for a couple of hours straight it started popping like crazy again when I let off the throttle just like I never rejetted and it was running lean. Any insight?

[YZROOSTINYA]

make sure there are no airleaks in the exhaust system

[Ricky g]

move the clip on the needle down 2-3 notches, if that doesn't help go one size bigger on the main jet, your running lean.

I would recheck the outwear cover and make sure it didn't come loose somewhere too.

RG

[Texan32]

ricky, i think yo are a little confused. The popping has nothing to do with the main jet or the needle. He said it pops when he lets off the throttle.

What is your mixture screw set at? It should be at stock setting, +/- 1/2 turns. Since you are running a 40 pilot (and assuming you have the mixture screw set properly) i would listed to YZ. Look for exhaust leaks. Perhaps the air leak get worse as the motor gets hotter.

[Ricky g]

[QUOTE]Originally posted by Texan32
[B]ricky, i think yo are a little confused. The popping has nothing to do with the main jet or the needle. He said it pops when he lets off the throttle.

Popping when you let off the throttle is a lean condition.

RG

[Texan32]

i know that ricky, but when you let off the throttle, the main jet and needle jet close. The pilot jet and mixture screw are what control the idle circuit, which is what is activated when the throttle is dropped (let off)

[DirtDiggler]

I forgot to mention that I'm no mechanic. I did what I did reading from an aftermarket service manual and being as careful as **** to make sure everything went back together properly. The air screw was turned out 1 turn which I was told to do by the guy who sold me the pipe and filter. White Bros told me 155/40 with the air screw back to stock which I did. I don't know where all the adjustments for the carb are other than the air screw and idle screw. I was going to attempt to change the needle setting as well as check for exhaust leaks and outerwear leaks. I would try to adjust some of the other carb adjustments but need to know where they are and which way adjusts what.

Thanks Guys, Diggler

[Texan32]

DON"T TOUCH THE NEEDLE. From what you just stated, all you need to do is turn the mixture screw out 1-1/2 more! I don't personally know ANYONE here that is running less than 2 turns out on their mixture screw (with a 40 pilot)!!!!!

Just set the mixture screw at 2-1/2 turns out and give it a whirl. Willing to bet she purs like a kitten after that!

[DirtDiggler]

I take it you mean the air screw on the engine(front) side of the carb?

[Texan32]

its kinda a pain in the butt to get to , but its on the bottom of the carb towards the intake boot (not the snorkle). It is the slotted brass screw in the middle of the two upper red arrows in the pic i attached. If you have the right size srew driver, you can adjust it on the quad without moving the carb. Turn the screw all the way in (don't put too much preasure on it). Then let the screw out 2-1/2 turns. Go for a ride and see how it does. Also, if it seems to run good, let it idle for 5 minutes or so and do a plug check. 2-1/2 turns may have cured the popping, but might be too far and cause a rich condition. Either way, adjust the screw 1/4 of a turn at a time until the popping is gone AND the plug isn't too dark.

[Ricky g]

Originally posted by Texan32
i know that ricky, but when you let off the throttle, the main jet and needle jet close. The pilot jet and mixture screw are what control the idle circuit, which is what is activated when the throttle is dropped (let off)

The low speed jet(pilot) controls throttle response from 0-1/3 throttle, the air screw is a fine tuning of the low speed circute, the needle controls the mid range circute 1/3-3/4 throttle, the main jet contols throttle response from 3/4-WOT. At best the air screw is going to help idling, it can either be to rich and idle rough or to lean and the engine races, opening the air screw 2 1/2 turns is worth a try, but if that doesen't work, the probabal culprit is the needle setting, or the outwear cover may have come loose and more air than expected is getting to the carb.

RG

[Texan32]

good point ricky. Digger, make sure your air boots are tightly secured!

[2K1 300EX]

This is a lil' off the subject but is the stock setting for the air screw on the 400ex the same as the 300ex. Or do you kow what how many turns out is the stock setting for a 300ex.

[DirtDiggler]

I'm going to try this stuff this weekend. So your saying make sure everything is secure and then try turning the air screw all the way in and then back out 2 and 1/2 turns. If that doesn't work try changing the needle to a richer setting I live in western NY but have no idea what the elevation is. I'm thinking something may have come loose because it ran real good for a couple of days and then in the middle of the 3rd day it started doing it all of a sudden.

[AtvMxRider]

I willing to bet it is an air leak and not the jetting. Cause mine did the same thing when I installed my e-series and the head pipe was loose.

[franciscoluis]

it happend to me when i rejetted mine, and also i have the same problem when i drop off the gas, then i move the clip one notch and that was all. now it runs vok and zero problems
Thanks

[DirtDiggler]

not to sound ignorant but you mean the clip on the needle?

[franciscoluis]

yes