Hey all I'm new to the forum , been riding AC's my whole life, many different sleds only 1 atv. I have a 98 400 4x4 and I'm having a little trouble with it recently, when I first start it ( warm or cold weather) it seems to take forever to warm up. If I choke it it'll run but when it's not choked it bogs down and wants to quit, after I get it started it will idle with no choke in a couple of minutes but when I give it gas it bogs right down( unless I let it sit and idle for about 10 minutes) after that it runs great. I'm stumped!


Thanks,
Gary

 

Welcome to the forums.
Is the gas stale, and old?
It wont hurt to use the 'choke', which is really a starter jet. It doesnt choke off any air, just adds some gas thru a small jet. Have you tried a new spark plug?
You can also try to adjust the mixture screw, richer, which effects only the idle circuit, and that should help it when cold. Try 1/4 to 1/2 turn ,out.

 

Thanks for the reply, new gas, new plug, I did adjust the carb some but it just seems to take forever to warm up, I don't remember it always taking so long maybe I've just become more impatient with age.

 

how many miles do you have on it for 1 cause it may be that you are losing compression and need to put new rings in it and 2 have you tried cleaning the carburator cause if there is 1 lil speck of dirt in the carb it can do that and 3 is your fuel filter plugged? and welcome to the forum you will find that the info on here is very helpful and good luck let us know how things go

 

Seems like a lean condition, in the idle circuit. (It runs fine when warmed up, and crappy when cold, idles fine with choke on.) How many turns out, is the mixture screw, from being lightly seated?
Hows the air filter? freshly oiled, or dry?
Could it be a vacumn leak, in the intake area?

 

Thanks folks,
It has about 900 miles on it, filter is a just cleaned and treated K&N, I don't beleive theres a fuel filter on it unless it's inside the tank, I've tried adjusting the mixture several times from 3/4 of a turn to about 2 turns, the problem is by the time it gets warmed up, which is when you 're supposed to adjust it ,it's running fine, I just cleaned the carb and pulled the tank and cleaned it so I could put fresh gas in it and while I had it off I used a clear fuel line and ran the machine with the tank on the bench and its' getting plenty of fuel, I'm kinda leaning toward an intake leak myself but all the boots are in great shape ( the machine has always been well maintained and garaged). My other thought was maybe valve adjustment but I thought that the fact that it runs so good when it finally warmed up seemed like a carburation issue. I did swamp it not long after it was new so maybe the ring suggestion is the problem.

Thanks again

 

You can be as far as 4 turns out from seated, before you need to go one up on the pilot jet. Try going 1/4 turn at a time, until you get to a max of 4 turns out.

 

Thanks I give it a try.

 

Hi Gary, I've got a 99 AC 400 4x4, it's pretty cold natured too. I'd bet your K&N might have aggravated your lean condition so the other fellers gave you some good advice on adjusting the mixture screw.
The starting drill on mine cold is full choke, no throttle, and I let it set and run a couple minutes while getting other stuff ready. You can usually hear it start loading up a little and start running rough, then I'll let it run at half choke for a bit. Once it's warmed up well it will start all day with no choke.
I'd guess the pilot is lean from the factory for emissions, mine will backfire when the throttles chopped winding down from a full speed run.
I seriously doubt you've got low compression or other engine trouble, I've got 1800 miles on mine and it's been a real workhorse. Good Luck, DK

 

Thanks,
That sounds exactly the way mine runs, It's been cold blooded since the day I got it but other than that it too has been real horse, I'm gonna give the adjustment a try and see what happens, I guess I just don't ever remember it taking so long to warm up.

Thanks again everyone