I purchased a used 500. It does not want to run if the choke is not partially on. The plug was somewhat fouled and it seems like the exhaust gets hot after just a few minutes of run time. It seems to drive fine but when it is in neutral the idol is high. I suspect that is from the choke being on. Any ideas???

 

Adjust the pilot screw to spec (I suspect it is too lean) and the idle speed to spec (the choke has to be off to do this so you will need to get the idle mixture squared away first), if it still doesn't run right you need to pull the carb and clean it. What year is the 500 as the determines which carb it has?

 

Thanks Bear. I will look into it. This is a 2003. It was purchased new in Maine. I presently have it in California, but plan to take it to Arizona and will be at about 6,000'.

 

so where in AZ are you headed? to be at 6000 ft? Prescott? if you want someone to go riding with you let me know. PM me.
sound like you running lean. that is why it needs the choke to be on to restrict the amount of air.... you could always pull the jet out and take it to a dealer and ask for the stock jet. and then witch one to run at 5000-7000 feet.


HR

 

I have the same engine you do and the only thing I've done is install and inline fuel filter (today fuel is dirty in more ways than one). Pilot jet should be 2 turns out and idle speed should be 1250 to 1350 rpm and float level should be 17mm or 0.7".

I live at sea level, a lot closer to the Canadian border than you and ride my 2005 400 and the wife's 2001 250 from our home base of sea level to 7000 feet and so far, not done a jet change or adjustment in the 4 years we have been doing it. The engines lose power as the altitude increases (physics in action) and it would help to change jets (I'm looking at the "Dial-a-Jet" system). My top speed drops about 9 mph when riding at 5000 feet (can't ride fast, higher than that because of the terrain). I would suppose that I would get back a mile or two with a jet change, but I'm trail riding and haven't been stopped yet.

 

There is no air restriction with these carbs. The choke is actually an enriching system which bleeds extra fuel into the back of the carb rather than the old choke butterfly at the front of the carb to restrict air flow and increase vacuum on the fuel delivery system. The main jet has no effect on the idle mixture, only when above idle speed and he said that works fine.

 

HR,
I got some land west of Seligman about 12 miles up in the hills. Plenty of trails to ride.

Bear,
I have purchased the sevice manual on CD. It identifies three jets: Starter jet, needle jet, and slow speed. It looks like the slow speed is what you are refering to when you say pilot jet. It also looks like that is the only adjustable jet.

I intend to put an inline filter on the fuel line. Had dirt problems with cement mixer carb.

If the float wasn't right I would think that it would starve for gas and die.

 

Idle mixture is the only adjustable one. A low float setting can effect idle more than high speed because these things are almost always jetted fat (rich) so as not the burn up the motor with extended high speed running.

 

GunTechPrep,

You may also want to check the valve clearances. If they are out by too much they can be a cause of hard starting and rough idle problems.

If you are worried about the exhaust getting hot and feeling as if it is going to catch your left leg on fire that is normal for a 500 AC.

There is also the idle adjustment **** on the carb you can turn to adjust the idle speed.

SJ

 

Got a chance to work on the ATV. the low speed was about 2 turns out. there was some dirt in the filter bowl. The slow speed jet is stamped 40. The specs call for a 75. The starter and the main are as to specs. Do you think this could be a problem?.