Problem

[rYan01400EX]

On my 406EX, I have the stock carbureator. It's giving me all kinds of fits and I can't discover the problem for ANYTHING. I recently put in a 42 pilot to cure my winter starting troubles. Here is where I think my mistake is. It has a 155 main in it now. The 155 is what the Big Gun manual calls for. However, Dynojet states that a 170 main should be used. Way to rich? Sounds like it. I know that when the carbureator is removed, I can see gas in the tube running from the box. Seems like way to much fuel. My quad is having trouble starting and idleing. This also leads me to the pilot jet. Should I return to a stock pilot (38) or should I just drop to a 40? This may not be it - just what I think. Let me know what you folks think! Thanks a ton!

[zrpilot]

Did you re-adjust your low speed jet when you put in the larger slow jet? Otherwise, I think you've got a float level, float needle/seat issue. The fact you have liquid gas in places that is does not belong makes me believe float. The jetting you mentioned is not that far off.

Just my $.02

[rYan01400EX]

How do I check for the float/needle seat issue? I haven't the slightest clue... If thats the case, what should I do?

[GPracer2500]

The float is non-adjustable on the stock 400ex carb. But the float valve could be leaking causing the bowl to overflow into your intake.

I'd start by removing the carb and making sure everything is properly cleaned (use carb cleaner and compressed air). Pay special attention to the float valve needle and seat.

And where is your pilot screw set?

[rYan01400EX]

GPRacer - the pilot screw is an item of focus aswell. I just read in the service manual that a wet plug could be from a misadjusted pilot screw... Great.. can deal with that... I have got it out 3.5 turns according to the dynojet guide. Seems like to much to me. I can't get it running enough to adjust it either. Im gonna turn it all the way in - bring it out a hair and see if I can atleast get it running and move it around from there... This carb has been cleaned 3 times. I would think no dirt - but after years of working with lawnmower carbureators that any small piece of dirt can cause the biggest problems.. Anyways, do you think a 155 main sounds correct though? It has ran good for a long time and then it just started to cut out and miss when wheelie-ing or when tacked out in any gear.

[GPracer2500]

If you put a 42 pilot jet in then Dynojet's fuel screw recommendation (suspect anyway, IMO) is out the window. So, yeah--see what you can do there.

A 155 is likely in the ballpark. Airbox lid on or off? Whatever the case, I'd think it should certainly run with that. The main has little to nothing to do with starting and idle performance anyway. But hands on testing on your end is the only way to dial it in "perfectly".

While the float bowl is off you can inspect the float needle and see if it's leaking any. Hook up a fuel line and manually push up on the float until it just touches the needle seat. It shouldn't leak.

You can check the float itself for punctures by holding under water in a sink or bucket. The floats should be air tight.

You may have already looked into some of these things--I don't know. Just throwing out ideas.

[rYan01400EX]

Yea, I'm sure the fuel screw is the culprit here too. I'm gonna bend me up a cheap screwdriver to get into the screw.. GP, I appreciate your help and your ideas. If you think of anything else.. throw it out as every idea you give me will put me closer and closer to the problem. I'm not exactly a slouch at mechanics but as far as Carbureators go... sure, I'm a slouch as they fool me like crazy.