rough idol on Edge 600 XC

[Paininthe#$%]

My friends Polaris Edge 600 XC is not idling properly. When you rev the engine the RPM increases and as you let off the RPM drops to ~3000RPM quickly and then stuters for a while and back fires as it eventually drops down to a more regular idol of 1000 - 1500RPM give or take. At higher RPM while you drive the machine it performs fine its only at idol that the problem occurrs.

We cleaned the carbs and it seamed to help at first for a few minutes but the problem eventually came back. We didn't want to completely dismantle the carbs and disturb the idol screws because we didn't want to resync the carbs... We can't seam to find any vacuum ports for syncing.

Has any one encounter this? Any Idea if it would be a carb problem or possibly the reed valves or something? The motor its self is fresh....

Any help would be appreciated.
Thanks

 

[sled]

Sounds like a vacuum leak to me.Have you check all you vent lines,fuel lines and also check the carb mounts to the engine.Could be a small crack.Well thats my tow cents.

 

[Rob1334]

Check carb boots, on the 6's they are crap, wish I had a pic on my computer of the ones I pulled off my 07, wish someone aftermarket could make something better than polaris. If it is it can really cause a lot of problems quick on an engine, might be good to check regardless.

But ya, sounds like a leak somewhere, Did it just start happening or has it always done this?

 

[Paininthe#$%]

Check carb boots, on the 6's they are crap, wish I had a pic on my computer of the ones I pulled off my 07, wish someone aftermarket could make something better than polaris. If it is it can really cause a lot of problems quick on an engine, might be good to check regardless.

But ya, sounds like a leak somewhere, Did it just start happening or has it always done this?

Yes it just started happening. Any Idea how the air leak could cause the high idle and backfire?

 

[Rob1334]

If it is the boots, it will screw up all the jetting. On the low end you wont be able to dial in your idle circuit, adjust all you want with the idle screw it will not stat constant, you will have bigger problems going on inside than the screw will fix. The added air will create a vaccuum around your reed cages, decrease the amount of mixing in your fuel-oil settings, and cause the sled to seem rich and can be running lean. Lean conditions of too much air will make it idle high, mine did the same, backfire, and I even had the engine flooding with oil, not pretty.

 

[Paininthe#$%]

We took the carbs off and checked the boots and reeds. Both the boots and reeds appear to be fine. We cleaned the carbs a third time. The plugs are also a nice tan color as well. Unfortunately it is still acting up. When the engine is at room temp it runs perfectly... It is only happens when it gets up to operating temperature that it acts up.

Is it possible that it is an electrical problem. There is a sensor on the side of one of the carbs I'm assuming it is a throtle position sensor. When I unplug it is seams to run funny even when it is cold (higher idle etc...). I'm not sure this could be causing the problem I am grasping at straws. What about a faulty CDI box could that cause this?


Please help.

 

[papajake]

check the idle screws on the side of each carb with engine off turn in till they seat then turn out 1and1/2 start sled the further you turn the screws in the ritcher the sled will idle you might want to also check you pilot screw for the right size

 

[Paininthe#$%]

The sled was bought used so it is possilbe that the carb is not set up properly I guess. Thus far we have assumed that everything is set correctly which can be a bad assumption! I will try the fuel screw and the position of the jet needle.

 

[Rob1334]

If you haven't checked the air screw do that first before the needles. It can be something real simple such as a air screw adjustment and that the carbs are not in sync.

 

[sledneck_03]

My 600 does the same thing, it either idles at 4000 or if i turn down the idle it dies. A friends 800 does the same thing...

 

[Rob1334]

My 600 does the same thing, it either idles at 4000 or if i turn down the idle it dies. A friends 800 does the same thing...

What you need to check is if the sled is cutting out below 4k rpm from being to lean or is it to rich? Yurs would be the same thing, ilde circuit is either too lean or too rich, if its carbed much easier to fix than EFI.

 

[Paininthe#$%]

Tried the fuel screw adjustment. The two carbs were already sync'd at 1 1/2 turns. I tried them 1 turn and 1/2 a turn and it still ran poorly (back firing and idleling poorly) We also tried adjusting the needle position it still acted up doing the same thing.

Is there any one familiar with defects in throtle position switches or CDI boxes? Is there any way they could be the cause?

 

[sledneck_03]

What you need to check is if the sled is cutting out below 4k rpm from being to lean or is it to rich? Yurs would be the same thing, ilde circuit is either too lean or too rich, if its carbed much easier to fix than EFI.

Played with the air screws and its fix

 

[Rob1334]

Played with the air screws and its fix

Did you fix it with the fuel screws or the air jets? Was it lean or rich? Glad your problem is gone!!! Frustrating problem I know!!!