2004 700 EFI only runs on one cylinder untill warm and ildes rough

[scat6]

Hi all, I'm new on here so any help would greatly appreciated!! I've got a 2004 700EFI that only fires on one cylinder when its cold out (cold being under 30 degrees or so). Once it warms up for a minute or two it fires on both and is fine all day. It also idles rough and dies at idle quite often. I've changed the plugs, put on a new T-BAP sensor, ran sea foam through it, had the CPS changed, still nothing helps. Once it's up off idle it runs great and doesnt skip a beat. Any thoughts?

[scat6]

I've also tried adjusting the throttle cable and that doesnt seem to help either.

[Bruce!]

Welcome to the board!

[4wheelindad]

Have you checked compression on both cylinders with the engine cold? I'm new to Polaris so maybe someone else has some better info, but if a valve is out of adjustment it might be held slightly off the seat until warm. This would show up as a low compression reading when cold. Low compression effects idle the most because at higher speeds the combustion event occurs before significant compression can leak off. Just a thought. Good luck

[dirtdigger]

Coil?

[scat6]

I've though about it possibly being coil or some kind of spark issue, never thought about the compression though. The thing is, and i guess I should have mentioned this before, if I crack it about 1/4 throttle while its cranking it will fire up on both cyliners every time, but still idles real rough at about 700-800 rpms and will die more often than not, but if I baby sit it and keep the r's up around 1500-1600 it's fine and runs good after it gets to temp.

[4wheelindad]

Still sounds like a compression issue. If it were a coil I don't think it would matter if you held the throttle open. Usually coils fail when they get hot. Take both plugs out and screw a compression gauge into 1 cylinder and crank engine 4 or five strokes [about 3 seconds] with the throttle held wide open. Repeat for the other cylinder. Be careful of the spark plug wires so you don't get zapped.

[scat6]

4wheelindad do you know what the compression should be? Just wondering...

[Phil030]

Factory specs in the manual I have say compression is 150 - 170 psi.

Leakdown service limit is %10 (which seems rather low to me, but I am new to ATVs).

[unclekato]

I would also check compression. Could be a leaky head gasket.