What does this?

[rYan01400EX]

Alright... another of my infamous threads attempting to get my quad to run - correctly.

Alright here it goes... Well - when running after a cold start it will idle sort of odd.. Like you can here it cut out shortly and then it rev right back to normal.. Almost within the snap of fingers. Then, hit first gear... it'll start to rev high and then it'll cut and miss crazy... hit 2nd... rev high then the same thing... Come out of 2nd and hit 3rd, then it just buries itself. It falls on it's face. I makes popping noises when throttle is all the way in and it just sounds "gurgly" I guess you'd say. It's not hitting the rev limiter at all. It never has before all of this happened. It seems like it heats up ALOT faster than usual and when it does, the miss gets worse. It also starts to show a noticeable miss in the idle. Far more noticable than when it's cold started. I thought maybe the coil is bad - not enough spark. Wrong - sparks like crazy. So, I'm looking at a fuel related problem. Carb has been soaked 3 times in cleaner to no avail. It's getting old as when my quad is idling - it sometimes misses so bad it'll shutoff. I have no clue whats wrong and any help is appreciated. I'm pretty sure this is fuel related.

Thanks,
Ryan

[PismoLocal]

Your jetting is off. What mods do you have on your bike and what elevation are you at?

[GlowBoy]

Yeah the jetting is messed up, take it apart and rejet it. What are your mods, tailor your jets to your mods. Other people can give you more input than me.

[400eXr1d3rZ]

Is your choke on?

[PismoLocal]

Originally posted by 400eXr1d3rZ
Is your choke on?
Thats actually what it sounds like. Ya make sure the choke is off. Don't worry it happens to the best of us.lol :devil:

[rYan01400EX]

No, the choke is not on. I know how that goes - done it before.

Anywho,

I have these things :

FULL Big Gun Race exhaust
406cc piston
Ported and Polished
K&N with airbox lid OFF

Carb. jetting :
155 Main
38 Pilot
Fuel Screw 2 1/4 Out
Dynojet needle 3rd position down
541 Ft. above sea level

**My jet kit is a dynojet stage 2 if it matters.

[kjbula]

Take the carb off and check to see if the choke lever is moving the butterfly thingy. Mine wasn't so I took the choke completely off. Good luck!

[rYan01400EX]

It is - everything functions perfectly! Thanks for the replies so far... Anyone else?

[GPracer2500]

So that 155 is a Dynojet jet?

Have you tried a smaller main?

[rYan01400EX]

I'm gonna try a 146.. sound good GP?

[GPracer2500]

Making small steps is usually best. If you have a 150 I might try that first.

Step down in sizes and see how it reacts. It it keeps getting better--keep going. If it's worse after the first change in one direction then try going the other direction.

Trial and error can be a big part of getting your jetting right.

[pman03]

I would say you are too lean. I have about the same set up as you...big gun slip-on, uni filter w/ no lid, porting, and a 11:1 piston and i am running a 160 main, 3rd clip on the needle, and 2 1/2 turns out on the air/fuel screw..the jets are dyno jets btw... My temp is about 40 degrees and about 1000' above sea level. What temperature is it there? The colder the temp the leaner your carb is going to get.

[GPracer2500]

One quick way to help narrow down if you're too lean or too rich is:

--Put the airbox lid on. If the condition improves you're too rich.
--Engage the choke a little bit (all the way or even half way is probably too much). If the condition improves you're too lean.

The idea there is to change the jetting by changing the amount of air the engine is able to suck.

[rYan01400EX]

It's backfiring through the carb... Ehh, timing?

Put that 146 main in... ran good for 5 minutes... got heated up.. backfired through carb... I started it back and could not push throttle maybe 1/4 the way or it would backfire through the carb. I'm lost.

[400eXr1d3rZ]

Originally posted by rYan01400EX
It's backfiring through the carb... Ehh, timing?

I suggest you go up on the pilot, that could be ONE of your problems, try a 42.

[rYan01400EX]

Tried that too.. not a bit of difference.

[jrm03]

raise the needle a notch. I've been told the cough through the carb is a lean condition