Help Arctic cat Jag Deluxe 440 (no power!)

[T_Snowbike]

Just got sled for my wife & kids to ride. But the sled has no power. It doesn't miss. No clue whats wrong except it goes about 20 mph. I know my way around engines but this has me stumped.

It has 2100 miles, very nice condition, electric start. I think it's a 1992. I also have a 1998 Jag340 (1700 mi) that runs perfect.

The carb is perfectly clean inside, jets are shiny and clean. Mainjet size conforms to the sizing/altitude table as on the decal.

It starts & runs easily. Judging by how the rope pulls the engine seems to be in perfect condition. Rope pull is feels 30% harder than the 340. I re-torqued the heads. It's not drooling anywhere. It's out in the boonies (in a barn thats 3 hours from home) so I have to get my all ducks in a row before going out there.

Can anyone offer tips? What kind of "reed" system does a Jag440 use?

 

[Idcatman1]

I would start with the drive clutch. Check for a broken spring or worn and stuck weights and or rollers. Does it rev really high or not much? Revving high but going nowhere is probably weights or rollers. Revving really low is more likely the spring. If everything checks out OK in the drive clutch check the driven clutch, a broken spring there could foul things up too, but I don't think I have ever seen a broken spring there. There are no reed valves in the 340 and 440 fan engines, they are just piston port designs. I have a couple 97 340 Pumas I could make you a good deal on. They didn't want to run either until I put new pistons in both of them. Good luck.

 

[m8magicandmystery]

maybe all is fine with fuel delivery at the lower end but just not enough at the higher load..fuel pump or vacuum line to pump...or it leans out to much..carb boots...crank seals..??

spray suspect area's with carb cleaner or wd 40 etc and see if engine rpm changes with the spray getting into the fuel air circuit through the breech..(if any)

 

[T_Snowbike]

Low end seems normal. I expected to see the mainjet plugged but as I said it's all clean.


Will look at the clutch, but I don't recall behavior like its stuck in 1st gear. I know my way around 2-strokes but new to snowmobiles. It sounds like its leaning out but plugs are burning normal. It doesn't run normal then starve so I don't think its fuel delivery to the bowl.

Thanks for the help, all ideas appreciated!

 

[T_Snowbike]

Found some of the problem. Fuel tank had about a pint of water in it. The gas cap has a clear plastic cover over the float guage, that leals water into the tank. I think the slug of water froze and didn't let enough gas thru.

Got all the water out last fall and its much better now, of course. But this Jag 440 doesn't have the pep of my Jag 340 (if the word pep can be used on a 340). Engine has good compression on the rope. Hard starting suggests lean mix but carburetor is perfectly clean. Plugs are brown. Pilot and main are clear. Still working at it. Unheated barn, prefer to research it on my phone near the woodstove then head out to the shop with new pearls of wisdom.....

 

[izzni]

I came across a Jag of the same vintage that was low on power as well. Took us forever to realize the crank had slipped.

 

[T_Snowbike]

How do you determine that? And how did you fix it?

I know engines well. Can I get to the flywheel while it's still in the sled? Can you retorque a flywheel and advance the stator?

You can tell I'm hoping for an easy fix. Have to research on my phone then do this work in an unheated barn.