2000 indy 500 wont stay idled down

[jonesin]

Hi guys any ideas?
The kids 2000 indy 500 will start right up and run fine but when you come to a stop it wont idle down. When the issue first started at the end of last year you could hit the choke quick and it would idle down and stay there, this year it will idle down for 3-4 seconds and creep up to 3000 rpm quickly.

I sprayed wd40 around the carb boots, the back of the primary where the shaft comes in and about everywhere else with no change in idle.
I checked the compression and its at about 85 psi +/-.....

It has about 7500 miles on it and was rebuilt at about 3500 with a burned piston, wondering if that is happening again....

It has been ridden either wide open or on the brake its whole life and been a really good sled, I'd like to keep it around...

Thanks!
Jonesin

 

[mezz]

One question, is the compression the same for both cylinders?-Mezz

 

[jonesin]

pretty close, it was an old style dial guage and both were approx 85 psi as close as I could tell.....

 

[dab102999]

For the heck of it try carb cleaner or starting fluid. Then I would say pull the carb and clean it real good and check the linkage/make sure still synced. You said used to be able to choke it and have it come off. Make sure your cables are free and returning all the way also.

 

[mezz]

For the heck of it try carb cleaner or starting fluid. Then I would say pull the carb and clean it real good and check the linkage/make sure still synced. You said used to be able to choke it and have it come off. Make sure your cables are free and returning all the way also.

x2 on all accounts, though, it does sound like it's sucking in additional air somewhere. Good luck.-Mezz

 

[toddspolaris]

Sounds like the pilot jets need cleaned, pull carbs apart and remove pilot jets and run a very small wire through them to clean, as fuel evaporates now it leaves ethanol residue behind in the small jets causing it to run lean. see it all the time. Just a thought

 

[jonesin]

is there an easy way to get the carbs out, any tricks?
they dont look like they will go into the airbox and probably not enough room to push into the boots, should I unbolt the boots from the block and take them off with the carbs?
if i dont get to them friday night i'll try next week and let you know what happens, ill be busy most of the weekend
thanks!

 

[dab102999]

Other guys will help you better on a poo but every sled I have had it is just easier to pull the air box. Get yourself some cable lube if you don't have any and get some in those cables too just to make sure. SLOWLY actuate your throttle and choke and make sure you don't "feel" any hang up. But as stated I bet 10 to 1 that a good cleaning will do the trick.

 

[jonesin]

I looked at it this morning before work and the airbox is attached to brackets on each side and I should be able to just slide it away to get them off I hope.
about 3500 miles ago it started idling up like this and I burned up a piston so I'm trying to prevent that......

 

[jonesin]

I am still at a loss
I sprayed brake cleaner everywhere with no change in idle. The right side is covered so if there is a leak in there I didnt get to it
I pulled the air box and carbs, the carbs were very clean, a slight discoloration in the bowl was all.
I pulled and cleaned the one jet from the bottom and sprayed all the openings etc, if there were other jets to pull I didnt see them.
The one thing I didnt do was pull the pin and dis-assemble the needle assembly. I could spray from the other side and see fluid coming out of it so I did flush it...
I hit the pin with a punch a few times but it didnt move and I wasnt sure if it was pressed in... on my dirtbikes it was usually loose and held in by the bowl or something...
I guess that I could pull the carbs again and try again, I couldnt believe how easy it was to get the airbox off and get to the carbs, very quick process

 

[dab102999]

You hit what pin with a punch??????

Did you put your fingers against both slides at once and slowly work your throttle to see if both slides are in sync and returning all the way to bottom?

When you sprayed did you spray around your exhaust and heads? Any small vac line on the block? If so spray them also.

Yes there has to be more then one jet. What model carbs do you have on that sled.

 

[jonesin]

You hit what pin with a punch??????

Did you put your fingers against both slides at once and slowly work your throttle to see if both slides are in sync and returning all the way to bottom?

When you sprayed did you spray around your exhaust and heads? Any small vac line on the block? If so spray them also.


Yes there has to be more then one jet. What model carbs do you have on that sled.

not sure of the carb model, muzino or something... I would have to look again
I sprayed everything, everywhere.... gaskets etc....
I was going to try to get the pin out that holds the little "u" shaped clip in place that keeps the needle from falling out, like I said, I have never seen them pressed in like this and didnt dare hit it very hard... but I figured if the cleaner was coming out through through the needle when I was spraying it would flush it out....
the cables all seem to work very smoothly from what I could tell, didnt feel any binding...
Thanks for the ideas though, I can try it again, the pin should come out, it has too I just figured I would try it without not wanting to cause any problems...

 

[mikedrh]

Almost all MIKUNI snowmobile carbs have an interference fit float tab pin. Use a small punch (a little smaller than the pin your taking out) a SMALL!! hammer and lightly tap the pin out. When taking the pin out you will need to support the tower it goes thru, if not you can break the tower off the body of the carburetor. I doubt that the needle & seat is what is wrong with your machine. Your cables probably need adjustment, both sync and slack adjustments.

 

[jonesin]

Almost all MIKUNI snowmobile carbs have an interference fit float tab pin. Use a small punch (a little smaller than the pin your taking out) a SMALL!! hammer and lightly tap the pin out. When taking the pin out you will need to support the tower it goes thru, if not you can break the tower off the body of the carburetor. I doubt that the needle & seat is what is wrong with your machine. Your cables probably need adjustment, both sync and slack adjustments.

that is what I started to do to get the pin out but decided it prob wasnt the prob since it flushed out.....
we have no snow so i will prob find someone to take it to that can sync it and check that, not going to get used anyway
thanks again

 

[G]

Is this a Pol model that runs the carb vent lines up underneath the handlebar cover? We had a Pol in out group that had that configuration. Similar situation with erratic idle. We had the carbs apart on the trail trying to figure out what the ####. All looked good. Later on we found that somehow a vent line out of sight underneath the handlebar cover was pinched off. Something to check if your vent lines do that too. Also you could check to see where your Fuel/Air screws are at. I think you just have air screws on that 500. They didn't have rackslides yet in 2000. See if maybe a screw has backed out. There might be a spring behind that could help to push it out. This hardly ever happens but you do have some miles on the thing.

 

[jonesin]

Is this a Pol model that runs the carb vent lines up underneath the handlebar cover? We had a Pol in out group that had that configuration. Similar situation with erratic idle. We had the carbs apart on the trail trying to figure out what the ####. All looked good. Later on we found that somehow a vent line out of sight underneath the handlebar cover was pinched off. Something to check if your vent lines do that too. Also you could check to see where your Fuel/Air screws are at. I think you just have air screws on that 500. They didn't have rackslides yet in 2000. See if maybe a screw has backed out. There might be a spring behind that could help to push it out. This hardly ever happens but you do have some miles on the thing.

the vent lines run down from the carbs and have a little filter on them, I blew through them to make sure they were clear, hard to tell with the little filter thing though....
what is a rackslide?
I didnt mess with the screws at all, it starts on 3rd pull every time and runs really well just wont idle down now.....

 

[racerxnet]

Pilot jet takes a very small straight blade screw driver to remove from the Idle well. You have to remove it (pilot jet) sometimes to get it cleaned with piano wire.

MAK

 

[jonesin]

Pilot jet takes a very small straight blade screw driver to remove from the Idle well. You have to remove it (pilot jet) sometimes to get it cleaned with piano wire.

MAK

if that is the one you get to after taking the bowl off, I did remove it, spray it, looked through it, ran wire through it...

 

[racerxnet]

You have 2 jets in the bowl area. Main Jet is the larger one that sits in the bottom bowl (hex end). The pilot jet (slotted) is in the idle well. Take a flashlight and look into the casting hole for the brass pilot jet. Make sure the idle circuit is clean. That would be the small hole(s) in front of the throttle slide when closed. Clean the idle circuit after removing the pilot jet. If need be, look at a microfishe online for the breakdown of a mikuni carb and where the pilot jet is. Your description of the jet removed is vague, so I am trying to be specific to your needs. Each carb needs to have the jets cleaned. If you did clean the pilot out and still idles high, you have a air leak somewhere, and another toasted piston to come.

https://www.google.com/#q=mikuni+carb+pilot+jet Link to view pilot jet.

MAK

 

[jonesin]

I looked it up and I did the main and pilot but not the air, I was afraid of messing up the setting. I might redo it and do like they said counting the turns in.....