Cylinder not firing at idle

[97srxXT]

Sled is idling real low and you can hear one cylinder going in and out. I can pull off that one cap while it's running and nothing changes. I tried trimming some of the wire off and screwing cap back on that and that didn't seem to do anything. Seems like it's a coil going bad. soon as I rev it up a little bit all cylinders are firing. What do you guys think?

Thanks,
Nick

 

[mbarryracing]

Do a compression test or cylinder leak down.
Had this when I detonated the PTO side in my 96 600 twin and took a ring land out. It wouldn't idle as it had very low compression but would then build enough compression at higher RPM's to run.

 

[97srxXT]

Ha I hope its not that, I just rebuilt the thing. Good idea on the compression test though I'll do one just to see.

Thanks,
Nick

 

[mbarryracing]

Atleast rule that out, doesn't take much to hurt a cylinder in these.

Did you try swapping spark plugs between cylinders/ See if it follows the plug? Might be a plug going sour...

 

[mopar1rules]

did you just pull this thing out of storage and tried getting it going for the season? if so, check pilot jets for pluggage.

 

[97srxXT]

I keep the sled in my heated shop at work and I start the sled every so often. That doesnt mean the pilot isnt plugged, But I went through these carbs during the winter last year. Another thing I guess I can check. I found a set of coils for $25 Im going to get them and have them for a back up at the least. The coils are original and the sled has over 7k on it. I'll throw a new set of plugs in too to rule that out.

Thanks,
Nick

 

[Mysledblows]

Start with the pilots.

 

[mopar1rules]

i know that even tho you just cleaned them (pilots) last winter, that doesn't mean that they aren't plugged up now. crap gas now a days has them pilots plugged within 2 months. check them pilots. i highly doubt its the coils. i've never seen them go out on a yamaha sled.

 

[snomofo]

Sled is idling real low and you can hear one cylinder going in and out. I can pull off that one cap while it's running and nothing changes. I tried trimming some of the wire off and screwing cap back on that and that didn't seem to do anything. Seems like it's a coil going bad. soon as I rev it up a little bit all cylinders are firing. What do you guys think?

Thanks,
Nick

It does sound like a compression issue or pilots but I just wanted to suggest not pulling the plug caps off while it's running. Without a ground path the high voltage has to go somewhere and it'll find a way usually through the coil housing. It's a good way to wreck a coil or worse, make it act intermittent or act up under high load/speed.

Try grounding it with a 12 volt test light if you need to check it dynamically.

 

[daman]

Start with the pilots.

x2......