Lets fix this...please

[jasmf24]

I'm working on a 99 warrior. It has a bog when you mash the throttle, also back fires out of the carb when you do this. I did the Bic pen spring mod and it helped some, but still have the issue (just not as bad). It idles fine, and if you roll the throttle on slowly... it will rev out symptom free. Mods are; HMF slip-on with no quiet core or spark arrester inserted. Lid is on with a K$N filter. Main jet is 152.5, Pilot stock. Screw 2.5 turns out. Not sure where the clip is on the needle. And carb is very clean.

Is the jetting about right (I couldn't find a jetting database here)? Any thought on the direction I should take next?

Thanks in advance.

 

[wv03warrior]

Might need to go up a size on the pilot and might be too big of a main jet. I'm no expert tho.

 

[lbjamm]

That's a pretty big main for running with the lid on. I think I'd drop it to 147.5, maybe 150. Pilot should be fine but I'd prolly set the screw to 1.5 or 2 somewhere in there.

 

[Gen1Pat]

Backfiring out of the carb is usually a symptom of a lean condition. You really need to plug chop it at idle, half throttle, and wide open throttle, to get plug readings and see is the engine is runnin lean or rich, and at what throttle posistions it is running lean/rich.

 

[jasmf24]

and at what throttle posistions it is running lean/rich.

Mid throttle it cuts out and pops. But only when you hit the throttle hard. With the lid off, it makes the symptom worse. 0-1/4 is fine. 1/2 throttle... bogs and backfires out of the carb.

 

[jasmf24]

Also, if I manually operate the accelerator pump (by giving it a more drastic pump) to coincide with the thumber, it runs fine.