11;1 440 jetting

[DAVE14]

My 440 runs well with a 42 pilot & a 170 main & Im at a 350 elavation so I hear , any way it runs well most of the time but on my way up the first few gears it gets crackly when Im in the throttle big time as if Im hitting the limiter already or starving for fuel it doesnt do it all the time but often enough when Im pinning it all at once to get up to speed & my mixture screw is out a good few turns for sure any ideas?

[ZSK]

Where's your needle at? How does the plug look? Does it feel like a hesitation or bogging?

[DAVE14]

the plug looks tan in coluor it looks great doesnt smell rich it looks normal like the good one in the book , but Im no carb expert especially on quads I dont know what you mean by the needle position

[ZSK]

From the tech articles:

The Needle and Needle Jet
The needle and needle jet are the componets that primarily regulate fuel flow between 1/8 and 3/4 throttle. The needle jet is seldom changed in everyday tuning, but it's still worth mentioning the fact that it's there. The needle itself is a basically a tapered rod connected to the throttle slide. As the slide opens the needle is pulled upwards. The needle is tapered so that as it's pulled up, it takes up less space in the needle jet. This allows the fuel flow to be gradually increased as the throttle is opened. The needle has a clip that allows it to be lowered or raised in relation to the carb slide, which gives an overall richer or leaner setting. Raising the clip up a notch drops the needle down farther, causing a leaner mixture. Lowering the clip raises the needle up, causing a richer mixture. You can also get different diameters, and tapers of needles. If the clip is lowered all the way, and the mixture is still lean, you need the next size smaller needle. If the clip is raised all the way, and the mixture is still rich, you need the next size larger needle.

Many of the newer quads, you need to roll into the throttle a bit, by jamming the throttle wide open it allows the engine to suck far too much air. Does the quad crackle under normal throttle input? In 3rd or 4th half throttle does is start to crackle or bog down?

If it helps on my 440 I had an open airbox, full system, stage II hotcam, 11:1 440, I was running a 168 MJ, clip in the second from the bottom of stock needle, 45 pilot 2-2.5 turns out.

[DAVE14]

thanks I will check that out it only crackles at sudden hard accleration, but not all the time it will handle any rpm & run fine as long as Im not getting there all at once & yeah I have an open air box , K&n & the hotcams stroker cam , powercore4 exhaust I would have thought my jets are big enough ?maybe not