Mach Z780 Cylender not firing

[Tatersaladx]

Well i decided, its almost snowmobile season so i wanted to see if my mach z was still running good. poured some gas in, the gas line was dry rotted, i replaced the gas line. started it up, it was idling a little rough, and it kept making a popping sound, then the sound stopped, and i knew something wasnt right, so i shut the machine off, felt the pipes and one of them wasnt even warm at all and there was this brown/black liquid all over the cylinder, especially around this round plastic thing(im not familiar with snowmobile engines), so i beleive, i blew a gasket, and the gas is old some im gonna change all of the fluids, gas, oil, and coolant, and check the plugs. and then check for spark, if that doesnt work then ill take the top end off and change the gaskets. and when it idles i can sometimes hear the cylinder trying to fire up. any ideas?

[RedRider_AK]

The round plastic thing is your powervalve (or RAVE valve, to use the Ski-Doo terminology).

[honda250sx]

Have the powervalves ever been cleaned. Im betting NO. Those are a must clean every 1000 miles. Even if you run the good exhaust valve oil. I would definetly hit those first. Mach's like pickup coils as well. Check spark. Report back.

[Tatersaladx]

It has spark, and i noticed that it looks like theres gas, coming out of the powervalve. Well it smell like gas but its black. can the powervalve be screwed up?

[ATCwithdrawals]

It has spark, and i noticed that it looks like theres gas, coming out of the powervalve. Well it smell like gas but its black. can the powervalve be screwed up?

I ve had these triples before and they can be figity on start up, especially when they have a few miles on them. This is what usually happens when the plug fouls. If you run it for awhile after this happens it will force alot of the unburned fuel/oil out the exhaust port and some of it seeps by the R.A.V.E valve diaphram. Get some new plugs and check for spark . Gap your plugs to .018-.019 this will help.

I switched to Amsoil semi-synthetic and haven't fouled a plug since. Just an idea

[nate b]

clean the carbs

[84honda200s]

ive owned plentty of sleds and usually when you are spewing crap out where you are its usually a bad plug (as said 2 posts above), carb's float is stuck or running to rich, or a bad coil.


get a new plug, check for spark. if you have spark...fire it up and if it does it again take the carb off and clean it real good. if it still does it maybe the rings are going and its not enough compression to compress the fuel enough do its thing.

but most likely its a bad plug.

[Tatersaladx]

It was the plug, i put one of the othe plugs in it and it fired right up. So im gonna go out and buy some, Iridium spark plugs and amsoil, then clean my RAVE valves. Should run mint. Thanks for the help

[84honda200s]

them irdium plugs rule. its all i use to run. 12-15 bux a plug but well worth it. glad to hear ya got it running. give em hell !!!!

[Tatersaladx]

Now im just waiting for the snow to fall. Hopefully this winter doesnt suck.