2004 Kingcat Jetting

[scotth]

I am looking for a little jetting advice for my 2004 Kingcat. I rode last weekend at about 4K feet and 32 degrees F, the sled was very boggy unless I really had it rapped out, no throttle response, smelled very gassy. The piston wash was also rich. My buddy with a 2003 1M 900 had no troubles and burned quite a bit less gas (not sure of his jetting). My sled ran okay (not great) previously at colder temperatures

Currently the sled is stock, running stock jetting, 360 mains, stock needles with 4th clip. I have read a pretty big range of jetting recommendations, so I though I would post and see what people are running.

I ride the sled in WA, 3000-7000ft, no colder than 20F for the most part.

Recommended jetting?

Main jets?
Pilot jets?
Needle?
Clip?
Air screw?
Fuel screw?

Thanks, Scott

 

[76FOMOCO]

just to preface this with every sled is a different animal and needs to be jetted by piston wash. providing all is stock,airbox,pipe,can ect. at the alt you listed.
Recommended jetting?

Main jets? would start with a 350 and go down as wash indicates. remember to jet for the coolest and lowest area you will spend the most time in and be careful below that. Chances are you will end up around 330 or 340 but take your time getting there.
Pilot jets? 50
Needle? ZR for a 900
Clip? center
Air screw? 1.75
Fuel screw? 2.0

 

[scotth]

Sounds good, I will get some mains on the way. Do the ZR needles help with the mid-range lean burn down condition?

What is the story with the air and fuel screws? I am used to 2-stroke dirtbikes with only an airscrew.

 

[76FOMOCO]

the zr needles do help a bit but still don't camp out in the 3/4 throttle. the tm40 on the cat are one of the few with the fuel and air screw just more adjustment.

 

[diggerdown]

I would open my fuel screws a little more and put my needles in the middle slot. If you are rich mid at 4000' with 360's you have to have the needles picked too high. Usually they are lean mid range but mine gets too fat if I pick the needles up, but I usually ride at 8000 to 10000'

 

[scotth]

I would open my fuel screws a little more and put my needles in the middle slot. If you are rich mid at 4000' with 360's you have to have the needles picked too high. Usually they are lean mid range but mine gets too fat if I pick the needles up, but I usually ride at 8000 to 10000'

Are you running ZR900 or stock needles?

 

[diggerdown]

Stock needles with 360 jets run 1100 mid range. 340 jets close to 1200. thats at 8000' 20 F 14/1 rkt head, speedwerx pipe and cpi front dump can.

 

[scotth]

Thanks guys, I will start by installing 350's and moving the clip to the middle on the stock needles.

You guys running different jets in the PTO and MAG sides? (why is that?)

 

[mp_2009]

pto/mag

i run 400 pto and 410mag the mag side is usually hotter from the pipe or pipes and ive been told the larger jet keeps it a bit cooler

 

[scotth]

Well, time for a follow up. I am running 350 mains, 45 pilots, 4th needle clip, in my 04 900, it runs strong in the mid and top end, but it is still boggy on the bottom end. Any other things I should look at for the low end bogginess? The power valves are clean, airbox is gutted. I think I will play with the air and fuel screws next time out, I think they are in the stock positions now.

 

[1Mike900]

Scott, At 32 deg. they do get a little fat, The needle clips I would put in the middle position, That will help the mid range to be a little more "snappy" I have the 360's,clip middle and 50 pilots. I am going to replace the pilots with 35's. The air box has a home made cowl induction which I do believe makes it leaner at the top end. It runs real strong with this setup! Except idle gurgles even in the mid 20's at stampede or goldcreek parking areas. I have also heard that 800 Polaris edge needles help with the midrange lean spot, But I would need more info on this. I wonder if Pierre's has an idea on this?

Mike

 

[scotth]

Thanks for the input Mike! I was definietly getting the gurgles last weekend at Stampede, it was warm and wet. However, my buddy with a 03 900 had no troubles, I need to check what he is running.

So you are going all the way down to a 35 pilot? I have some 40's, might need try them.

 

[1Mike900]

40,s might do? Our temps around here are really not that cold, But if it is better to error on the side of caution! The idle circuit is cut off early so no real power is being created there. Cat made everything fat when designed for different climates.

Mike

 

[Arctic Thunder]

With the stock pipe and can I ran 350 mains. I had to drop the needle one step leaner than the middle. I know this is the wrong way with the all the mid range burn downs but it really cleaned it up. I just don't ride it in the mid for miles at a time. Very crisp and responsive.

Thunder

 

[diggerdown]

Are you running with the air horns in or out? The air horns help with low rpm by creating more turbulance and higher speed air passing through the carb throat.

 

[scotth]

No airhorns now, but my sled was exhibiting the same behavior last year with them in. I don't think they are the cause.

 

[1Mike900]

If the '03 is running the same set-up, Then it is because he has the more advanced timing curve. Another thought, How many miles are on yours? Maybe you have a couple bad reed pedals that are not seating too well? I still use the airhorns, They do increase intake speed as posted above!

Mike

 

[scotth]

About 2000 miles, might need to take a look at the reeds like you said. I never really have looked closely at the servo motor and cables for the powervalves, might be something to check.

 

[scotth]

The powervalves and servo seemed okay, I adjusted the cables a bit and felt for resistance and watched the servo cycle. The piston wash looks a little rich, so I have no qualmns going down to 40 pilot jets, so that is my next step I think. I will take a look at the reeds as well when I pull the carbs.

 

[scotth]

The sled ran the same after the power valve adjustment. I just checked the reeds, looked like new. Threw in some 40 pilots, will check it out this weekend. Maybe I am expecting too much from a carbed big twin?

What does everyone run their fuel and air screws at?