Hey Guys,

Newby here, bought a '98 mach z this year, but have some concerns. I've already cooked two pistons on two separate occasions. One real bad, the other one not so bad. This has led me to question the setup.

Here's what i got:
mains: 300 310 300
Pilots: 45's
needles: stocks i presume, set at the third clip
just aligned the clutch with the tool...it is good
airbox is currently gutted, putting the shelf back in after most recent meltdown
other than that the sled is bone stock...from what i know

Question is:
whenever i run the sled full throttle for any more than 4 to 5 seconds, it burns down. I'm thinking its running lean, but i need someone to tell me what a good recommendation would be for the mains. I've heard having the airbox gutted is not a good plan. Therefore its going back to stock with the shelf in place.

Also...although i know this thing is a triple and it is a pig on gas, is 42 liters in 70km a little excessive, or is this normal?

Thanks to everyone who replies

Gutting the Airbox allows the machine to suck in more air, if you don't feed it more fuel, bam, you lean out and burn down a piston. I'm not much of a tech guy but I've been told this from my mechanic. My sled is a 97 with gutted airbox, but I also have the Jaws pipes :D and it revs around 9000 wot. I think the mains a 410's if that tells you anything about adding more fuel. How's the oil consuption? Does it run hot at all? What about the plugs, what colour are they?

I'd start with putting the shelf back in, then run it and check the plugs. That should give you an idea if you need to do a little more adjusting. Hope that helps.

Oh and one last thing, if you haven't cleaned the carbs then I would also suggest doing that.

I think stock jetting on a 98 was 330 or 340 mains. You not only leaned it down to far but gutting the air box leans it even more.
Being under-jetted to 300's + 3-4 sizes in the gutted air box would be like running 260 mains if your sled was bone stock!
Leaner isn't always meaner, it takes fuel to make power!

As others have pointed out with a gutted airbox you have to jet up not down. I have a 98 Mach Z and the stock jetting is 310-320-310 (Doo updated it as it originally came to fat). The clip should be on #2 assuming it is the stock 8ABY1-40 needle and the pilots should be 50's. Timing for that year is 0.065" and the air screw should be 4 turns out. All this info is from the 1997-2001 Skidoo spec book which contains various useful specs. If I recall correctly it was only around $20 Can. and worth every penny!

Hey Guys, thanks for all the replies!!!

The box will definately be going back together, and i think i'll be going with the 310 320 310 set up. As far as the needles go, what would putting them back to #2 as opposed to #3 do as far as engine performance and gas consumption

By the way, the oil consumption is pretty heavy, like 2 liters in 70kms....I actually was just about out when it blew the other day. I didn't see the light on...its very very dim in the daylight. Any reccommendations?

Thanks

Skinny Ryan

p.s. my elevation is about 1500ft. here in Regina

Originally posted by SkinnyRyan@Feb 11 2004, 07:50 PM
Hey Guys, thanks for all the replies!!!

The box will definately be going back together, and i think i'll be going with the 310 320 310 set up. As far as the needles go, what would putting them back to #2 as opposed to #3 do as far as engine performance and gas consumption

By the way, the oil consumption is pretty heavy, like 2 liters in 70kms....I actually was just about out when it blew the other day. I didn't see the light on...its very very dim in the daylight. Any reccommendations?

Thanks

Skinny Ryan

p.s. my elevation is about 1500ft. here in Regina
It would richen up the midrange. With stock jetting you should get 9-10 mpg unless you are busting powder or putting it to the bar every chance you get and spinning excessively. As for oil I normally burn about a litre every hundred miles.

While you have your carbs apart,check all jets for blockage. Pilot,needle jet and main jets. Also check your carb boots for tears all around.These rubber boots loose their flexability after a while and crack,creating an air leak.Don't just change your jetting and assume you've fixed the problem.Eliminiate all other variables,of a lean running motor!