99 Articat 700...input needed please

[Semi Extreme]

I have a bit of an issue with my 700 and I would really appreciate some input.
I am trying to sell this sled but i can not sell it till I figure out why it has this idle issue...
When I fire it up cold it will start and run great for a few minutes then it will pop or backfire out the exhaust and make a weird hollow sound then run fine again, after it warms up it seams to run good. When riding, it has gobs of power but when I bring it to a stop it will idle high and after a minute or so the idle will drop down to normal and it will run fine.
I have replaced the intake boots, cleaned the carbs, checked compression and all seams good.
Last weekend I cleaned the carbs again and it Idled nice and did not pop once so I figured maybe it had water in the fuel and called it good but last night I was curious and started it up and it was back to it's old tricks...pop out the exhaust and make that funny hollow sound then idle good again...well...now I figure it may be an issue with the pilot circuit
One thing about this engine though and I pray this ain't the problem...It did have an over heating problem when I first got the engine rebuilt and it turned out to be the thermostat but only figured this out after it went through two pistons.
I found out that the pistons are sensitive to heat and the little pins that hold the rings in place will work loose and the rings will turn on the piston, catch the exhaust port and well you know what damage happens then...Now I am wondering when the rings caught the port do you think that it may have knocked the crank out of phase ?
I sure hope not but any input would be greatly appretiated....thanx in advance and I will answer any input.

 

[Zar]

During the high idle period ( after you have been riding ) flick the choke for a fraction of a second and see if the idle resets to normal. If the choke trick works then check your air screw ( your mixture is too lean during idle ). Does your machine idle fine at higher evelations ? I also had a similar problem and the air screw needed adjusting and the carbs needed to be syncd for Idle adjustment and air screw adjustmen. I hope this helps

 

[Semi Extreme]

During the high idle period ( after you have been riding ) flick the choke for a fraction of a second and see if the idle resets to normal. If the choke trick works then check your air screw ( your mixture is too lean during idle ). Does your machine idle fine at higher evelations ? I also had a similar problem and the air screw needed adjusting and the carbs needed to be syncd for Idle adjustment and air screw adjustmen. I hope this helps

Yes it does drop the idle after flickin the choke so I will try that today. the jetting is all stock I think from 5 to 9000'.
I can work on them but I am not the best at fine tuning these things. I do have a carb sync tool so maybe I will have to have the patience to check it.
thanks Zar ! to ya

 

[Zar]

Yes it does drop the idle after flickin the choke so I will try that today. the jetting is all stock I think from 5 to 9000'.
I can work on them but I am not the best at fine tuning these things. I do have a carb sync tool so maybe I will have to have the patience to check it.
thanks Zar ! to ya

Let me know it you get it tuned I am curious ?

 

[Semi Extreme]

Let me know it you get it tuned I am curious ?

Well before I fired it up I checked the balance of the carbs(passed) and checked the fuel screws and both were at 1.5 turns out so I set them to 1.75 turns, put it all together, started it up and seamed to run good and returned to idle better but I think I may have to put larger pilots in.
Do you or anyone know how many turns out the screws can go before going to a larger size pilot ?

 

[Zar]

Well before I fired it up I checked the balance of the carbs(passed) and checked the fuel screws and both were at 1.5 turns out so I set them to 1.75 turns, put it all together, started it up and seamed to run good and returned to idle better but I think I may have to put larger pilots in.
Do you or anyone know how many turns out the screws can go before going to a larger size pilot ?

Sorry I don't know for sure. I recall that in general on Mikuni carbs the typical air screw turn out is 1- 1.5 turns. I am not sure about the max turn out before you go to a diffenent pilot jet. I know on the low end is if you are less than 1 turn - change to a smaller jet but I am not sure if you can go to 2 turns ( or more ). It's worth a try before you go thru the hassle of replacing the pilot jet