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Discussion Starter #1
For a while now my 400 has not been able to stay idling when its cold out (well I'm not sure if cold has anything to do with it but it started when it got cold)

I read about the common carb issues on them and it might be a clogged choke circuit in the carb but i cleaned it all and sprayed carb cleaner in everything.
didn't do anything,

So i sucked it up and bought a new carb rebuild kit that comes with the new jets, needle, seat, jet needle etc etc. Put that in today and its still doing it!

I'm stumped. I thought I was fairly good at them carburetors but every time they throw something new at me..
 

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Welcome to the board!
 

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Just because the jets are new doesn't mean the passages in the carb are clean. You could also just need to turn the idle up a bit. Sometimes in the cold the run different. Also check your carb mount for cracks and air box the be sure it's hooked up tight and clamped down good. Any air leaks will cause erratic running issues on them.
 

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Discussion Starter #5
I tried bumping up the idle, which works great while its cold. but its weird it hits a certain point where it decides its warm and when that happens the idle shoots through the roof to like 2800-3000rpms, which makes it hard to shift and i feel like something will break
 

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Discussion Starter #6
have you attempted to dial up the idle? make sure no tears in the diaphragm on top of the carb. check for air leaks
Yeah it thought that may have been the case as well so I checked that when i changed the pilot air jet (I think thats the one up there) and everything looked mint..
 

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The pilot jet is in the bottom of carb, down in a hole , takes a small screw driver to remove it,Have to remove it to clean it, main jet is the larger one in the bottom, did yopu unscrew choke , remove plunger and cable and make sure that was clean with carb cleaner? To check carb boots, spray carb cleaner at them while its running, if motor speeds up or slows down, boot is cracked, adjust idle on the carb, check slack in throttle cable, should be 1/8 inch at thumb throttle.
 

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Discussion Starter #8
The pilot jet is in the bottom of carb, down in a hole , takes a small was, ew driver to remove it,Have to remove it to clean it, main jet is the larger one in the bottom, did yopu unscrew choke , remove plunger and cable and make sure that was clean with carb cleaner? To check carb boots, spray carb cleaner at them while its running, if motor speeds up or slows down, boot is cracked, adjust idle on the carb, check slack in throttle cable, should be 1/8 inch at thumb throttle.
I pulled the choke cable and sprayed it all out when I pulled the carb completely off. There was a jet that came with my rebuild kit they called the pilot air jet. It went in the top half of the carb under the diaphragm off to the side. Everything seems clear and clean. When I took it apart I was surprised how clean everything was, but then again it has almost no hours on it for the year. The throttle cable is good but I wonder if it.might be the choke cable that's out of adjustment. There's more slack in it the spec. But that shouldn't matter all that much as long as the plunger sits on the orphice and pulls off when you pull the choke open.
 

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Discussion Starter #9
Bump

Just in case anyone has a new ideas?
I pulled the Carb back off and made sure the choke circuit was nice clean and clear as well as the idle circuit I put it all back together and then adjusted the choke cable to spec and made sure the throttle cable was adjusted to spec, Which it already was.
 

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Sounds like you checked the carb ten times already, I would look for an air leak that may be heating up then closing with temp difference. Its either that or your carb slide is hanging up or a rough spot in your throttle cable. make sure its routed right and rests freely.
 

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Discussion Starter #11
I know the throttle and the choke cable are resting nicely, And the slide is good. Everything I checked last night while fussing with it. The choke cable was a little loose but I took the play out of that. The only thing it might be is an air leak, which would have to be after the carb. Which narrows it down to only that little boot going into the head... hmmm. I wiggled it around last night to look for dry-rot crack and I didn't see anything. I wonder if it could be the gasket under it?
 

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Discussion Starter #13
The choke is adjusted to spec although I was entirely confident of the adjustment method on it. I know other choke cables I've seen on other wheelers have an inline adjustment with a jam nut, These don't I guess? its just a nut that screws into the carb, then an adjustment nut behind that that you back out to remove the play in the cable. No jam nut though. So whats there from stopping the cable from vibrating back in and getting loose again?

I'll check for air leaks this afternoon when I have some downtime
 

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Discussion Starter #14
I may of just had an epiphany, I had to replace the stator not to long after i bought the wheeler, From reading the service manual it looks like with a warm engine the time retards approximately two degrees, I wonder if I may have put that stator plate on in slightly the wrong place. and the timing is too far in advance when the engine is cold causing it to fire too far before tdc which basically makes it die?

By the way no air leaks either
 
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