Hi everyone, I am hoping somebody here may be able to help me with this problem a friend of mine is having. He has a 1999 Arctic Cat ZRT 600 and one of the cylinders does not fire at all. The cylinder is getting spark, so I don't think that's a problem. As for compression, this cylinder has about 105 psi.....the other 2 have about 120-125. We changed the piston and rings in this cylinder and the compression stayed the same. The cylinder itself looks good and isn't all scarred up or anything like that. The cylinder is getting fuel....after the sled runs for a little bit you can see the fuel on the spark plug. He tried different reeds and even switched the carbs around, but this cylinder will not fire.....the pipe stays ice cold. Before last years season was over, the snowmobile was running great....

Thanks in advance for any help with this.

You've changed the plug,
...and switched the plug wires around too, right???

Hey konkinj, yes new plugs were tried, also tried swapping out the wires, new reeds. Pretty much tried everything that has come to mind and it's always the same result....the exact same cylinder....dead.

well by swapping the plug wires from one cylander to the other, you would see for sure if its getting spark,,,you know the good one is, but by swapping, if the good one still runs fine, then you know that the problem isnt fire,,,,,
now you go to fuel,,, try swapping the carbs,,,,, does the good one still run right??? if it does,,,,then I would say it has to do with the compression ,,,,,

Mine did the same thing, it had a small piece of dirt in the pilot jet and prevented that cyclinder from running until I hit 3/8 thro or more, the plug had oil on it and the smell of gas, new pilot jet and running fine again. If that isn't it check the reeds, plugs ect.

Thanks again for your replies! The carb was cleaned very well and it was also exchanged for one off of a "good" cylinder, but the results were the same. Reeds were changed, plugs were changed...cylinder gets a good spark to it, but will not fire...pipe doesn't get warm at all. I think its kind of odd how the compression on this cylinder is lower than the others, even after changing to a different piston and rings. Would a crank seal cause this problem?

Which cyclinder is it?????? Is it the cyclinder that has the pulse line connected to it?
A crank seal, I hope not.

Originally posted by Thunderman@Jan 3 2004, 07:32 PM
Thanks again for your replies! The carb was cleaned very well and it was also exchanged for one off of a "good" cylinder, but the results were the same. Reeds were changed, plugs were changed...cylinder gets a good spark to it, but will not fire...pipe doesn't get warm at all. I think its kind of odd how the compression on this cylinder is lower than the others, even after changing to a different piston and rings. Would a crank seal cause this problem?
Thunderman,I've had a cylinder head leak and that was enough to prevent sufficient compression and the cylinder didn't fire. Sounds like that comp is to low.
Look for blow by around the jug.
A bad crank seal, maybe. I'm not sure if it can cause low psi.I do know it can lean out a cylinder so maybe it's totally shot.

Originally posted by zeng62@Jan 3 2004, 08:18 PM
Which cyclinder is it?????? Is it the cyclinder that has the pulse line connected to it?
A crank seal, I hope not.
Sorry, I'm not too sure what you mean by pulse line, but it is the cylinder closest to the clutch.

Originally posted by JBK@Jan 3 2004, 08:27 PM
Thunderman,I've had a cylinder head leak and that was enough to prevent sufficient compression and the cylinder didn't fire. Sounds like that comp is to low.
Look for blow by around the jug.
A bad crank seal, maybe. I'm not sure if it can cause low psi.I do know it can lean out a cylinder so maybe it's totally shot.
Thanks JBK, I will be sure to tell him to check real good for leaks around the cylinder....is there any easy way to do this?

Look for wetness around the seams. Im not sure how to test for pressure or vacume leaks... i cant recall. but ill ask around and PM you.

hay i may be off here but, have you checked the choke goin into that suspect carb?????????????, if its stuck on it can do very weird ####

The impulse line is a rubber hose going from the crankcase to the fuel pump which provides the +/- pulse that opperates the pump.
I'm not sure where the impulse is picked up on this engine.

Well the problem is fixed!

I appreciate everyone that tried to help out. I mentioned the choke to him, as katmanzrt600 suggested, and he's like "you know what, the choke cable was acting a little funny". Well, the problem was inside where the 3 cables hook into one..not sure what this is called. Anyway, it was messed up there and even though the carbs were switched around, the same cable was put back into the carb for that cylinder. But anyway, it was like the choke was on the whole time for that cylinder. He fixed the cable and now the snowmobile is running fine. :)

Thanks again to all who responded, your help was greatly appreciated!

yep,,,thatll do it,,,,glad to hear you got it running again without many problems or cost,,,,, enjoy!!!!!!