PTO side cylinder not firing

[toofast250r]

About 2 weeks ago I started my sled on the trailer and noticed that it sounded like it was misfiring really bad. I pulled the plug and couldn't see a spark, but the plug was also pretty oil soaked so i don't know if that was THE problem or just a contibuting factor. I put the plug back in and could not get it to run. i changed the plugs and it fired up, ran OK for a while then started misfiring again. So i dropped it off at my mechanics shop. I went there tonight and was told they had no trouble getting it to run during the week and they said it was running fine until last night, it started acting up like I had described to them. Unfortunately they were unable to find any electrical problems. They replaced the throttle cable- they told me several weeks ago it would need to be replaced- and upon doing such had noticed the tops of the carbs where the cables go in were tightened all the way down and also said something about a needle (sorry I might not be 100% spot on with what I'm saying I'm sure he tried to dumb it down for me so i could understand!). So my carbs were adjusted and now in sync (apparently they weren't before) and has soooo much more power, but they are still unable to find the exact cause of my PTO side cylinder misfiring. They said I may have not been able to see a spark due to all the oil on the plugs, but maybe the oil on the plugs was because it was not firing also. I've been advised to keep a close eye on it to see if it happens again. Now I'm super nervous to ride anywhere far from my truck and house in case it takes a crap on me. Does anybody out there have any ideas of what it could be? My mechanics are real good and always have my best interest at heart- so if there are any other reasons my sled could be acting like this I'd like to bring it to their attention.

[rj]

Plugs get wet fouled and will not spark anymore and must be replaced.
Carbs out of synch will contribute to the problem as will a stuck choke.
If putting in new plugs solves the problem, it will likely save it every time.
Just carry at least one set of spares (new) that you can put in if needed.

[daggerdoggie]

I assume they have checked the compression of both cylinders. If that is good and the carbs are clean and in sync, check the PTO seal.

[arcticcatmatt]

Carbs cleaned, chokes set, synced... you are aready to rip IMO just like the other said.

Daggerdoggie mentioned PTO seal.. IMO a bad PTO seal would never cause that because if you had a bad PTO seal it would lean out that cylinder thus making the plug white.. not black (rich). And since the problem went away, I definitely think its not a PTO seal and was just a plugged passage way on your carb.

And next time when checking spark, use a inline spark tester. They work much better than looking at the plug itself. They are about 5 bucks.

[toofast250r]

I appreciate all the input guys. I'm gonna stay close to home just in case I have any issues and if all goes well and I get a little more faith in the sled I will venture out further next weekend. I really wanted to go riding again with you Scott, I really had a great time and the trails we rode that day were awesome, a little woods, some big fields, a great guide... keep your fingers crossed all!

[316duke]

Remember that your sled will foul a plug faster in the summer temps then when its cold out because of the jetting, take it off the trailer and rip around the yard to clean it out