[flowincat]

I got it all back together today 1996 Polaris Ultra 680 SP with PSI pipes. I have 400 pto 400 center 410 mag side main jets needle set at second from top clip pilots are 25 and air screws 1/2 turn out. primary clutch is red EPI spring and 10A/55 gram weights secondary has new super slippery SLP buttons a 42/34 helix and a purple EPI spring. This thing fricken flys now my fiance has a 2000 Yamaha SRX700 with triple pipes and a aftermarket can and it has been clutched also and my Ultra will run right with it if not beat it. I LOVE IT!!![/b]

Hi there. I found this thread and got some anwsers to my jetting questions. Did you go with the P-8 needle jets and PSI needles?

Are you still getting 9 MPG

I am still averaging around 3 if lucky

 

[mnbowhntr]

yeah I'm still getting around 9mpg with mine it is still running alittle rich on bottom and mid I think i may even drop it down to 20 pilots then I have to figure out a good needle and needle jet combo to clear up my mid range as I have the needle all the way down in its leanest position and it still is a little rich in mid range

Hi there. I found this thread and got some anwsers to my jetting questions. Did you go with the P-8 needle jets and PSI needles?

Are you still getting 9 MPG

I am still averaging around 3 if lucky[/b]

 

[U-Con]

The SLP needles for low elevation were designed to run with P-4 tubes not P-8's. The stock 6DH8's were pigs on gas, that's why they cut their own. If you were to try and mic them, I think they were fairly close to the stock SPX needles, if I remember correctly. HTG uses the stock 6DH8's, you'ld need to at least run 3.0 slides and Q-2 tubes. With P-4's, I've never had a problem with the SLP needles. I even used 45 pilots for the throttle response, but had backed off to 40 pilots for trail riding. No plug fouling what so ever.

 

[mnbowhntr]

huge difference between SLP and PSI pipes not even close to each other in the carb set up

The SLP needles for low elevation were designed to run with P-4 tubes not P-8's. The stock 6DH8's were pigs on gas, that's why they cut their own. If you were to try and mic them, I think they were fairly close to the stock SPX needles, if I remember correctly. HTG uses the stock 6DH8's, you'ld need to at least run 3.0 slides and Q-2 tubes. With P-4's, I've never had a problem with the SLP needles. I even used 45 pilots for the throttle response, but had backed off to 40 pilots for trail riding. No plug fouling what so ever.[/b]

 

[pockets]

You could try the SPX 6CEY06 needles, with Q2 247 nozzles.

 

[mnbowhntr]

is that for PSI pipes or SLP pipes?

You could try the SPX 6CEY06 needles, with Q2 247 nozzles.[/b]

 

[mnbowhntr]

I want to make sure I'm understanding needle jets and needles correctly a P-4(247) let in the least amount of air the P-8(247) lets in somewhere in the middle amount of aire and the Q2(247) lets in the most air now for needles the bigger the needle the less fuel it lets in and the smaller the needle more fuel it lets in or is it reversed? I'm trying to figure out more air less fuel

is that for PSI pipes or SLP pipes?[/b]

 

[U-Con]

I want to make sure I'm understanding needle jets and needles correctly a P-4(247) let in the least amount of air the P-8(247) lets in somewhere in the middle amount of aire and the Q2(247) lets in the most air now for needles the bigger the needle the less fuel it lets in and the smaller the needle more fuel it lets in or is it reversed? I'm trying to figure out more air less fuel[/b]

The jet needle and needle jet (tube) work together to meter the amount of fuel, mostly in the 3/8 to 3/4 throttle range. As the needle is lifted out of the tube by throttle movement and by the taper design of the needle, more gas is allowed through. The P-4 would have a smaller opening through the tube and as you increase in number size through to, say, Q-2---the orifice size increases about .010" for each increase in number designation. (P-4 being leaner, Q-2 being richer, usually all in even numbers, but not always) The throttle valves, allow the airflow to increase at a given throttle position, mostly from just off idle to about 3/8 throttle position is where this has it's greatest effect. A 1.5 being richer to a 3.5 being leaner.

 

[mxracer68]

Drill out the pilot air bypass (remove the pilot jet and drill straight down through where it threads into) to 1.0 mm (.040"). Start with 30 pilots, air screw at 1/2 turn, the slp 14-101 low elevation needles and stock 247 P-4 nozzles. 380/360/380 mains. Run BR10ES plugs, only good fuel, and if you are 1500ft. elevation, stock timing of 16 degrees at 8000 rpm. Take the weights out of the primary clutch and run the engine up to that rpm to check with a timing light. As said, belt to sheave clearance must not be more than .020", and deflection 1 1/8" to 1 1/4".

Pockets, if I have my flow paths correct this drill out modification will lessen an overfuelling/loading issue at low throttle openings with the sled under load? (heavy snow, 1/8 to 1/4 throttle opening). Or does this richen that circuit? I need leaner!

I have 30 pilots already but seems to load up if I creep along in heavy snow ie. maneuvering through the bush etc.

 

[800ultra]

Open the air screw if its fat ! You can open it 2 turns from closed! If still fat close screw to 1/8 turn and go to 25

 

[mxracer68]

Open the air screw if its fat ! You can open it 2 turns from closed! If still fat close screw to 1/8 turn and go to 25

Ya you bet. Everything is crisp and clean until the clutch is engaged and the sled is under a bit of load then it would load up/overfuel before it can get going. I was hoping drilling out the bypass hole as mentioned above would help keep the mixture a little leaner while the throttle is nearly closed.

But I don't want to hit my carbs with a drill bit until I know why the service bulletin called for oversizing to 1mm.

 

[800ultra]

At clutch engagement the needles are taking over ! Drop the needles one clip and see what happens... What year is the sled And is it an RMK? I just set a SKS Up with SLP Low RPM pipes 2.0 slides 50 pilots drilled the carbs to 1mm , 6CEY06 needles Q2 tubes and 380 mains runs like a top! I found the slp jetting to be a little funky

 

[mxracer68]

At clutch engagement the needles are taking over ! Drop the needles one clip and see what happens... What year is the sled And is it an RMK? I just set a SKS Up with SLP Low RPM pipes 2.0 slides 50 pilots drilled the carbs to 1mm , 6CEY06 needles Q2 tubes and 380 mains runs like a top! I found the slp jetting to be a little funky

My question is:

What is drilling the pilot hole to 1mm accomplishing? Leaner or richer on pilot circuit?
Thanks,

 

[800ultra]

I really dont think it will make it leaner. I think the idea was because with a larger pilot say a 40 50 or so the hole was to small to flow the larger pilot.. and maybe the larger hole made the pull on the pilot circuit stronger

 

[pockets]

Pockets, if I have my flow paths correct this drill out modification will lessen an overfuelling/loading issue at low throttle openings with the sled under load? (heavy snow, 1/8 to 1/4 throttle opening). Or does this richen that circuit? I need leaner!

I have 30 pilots already but seems to load up if I creep along in heavy snow ie. maneuvering through the bush etc.

Yes, it makes that transition leaner. The 1997 and 1998 Ultra came this way.

 

[800ultra]

Yes, it makes that transition leaner. The 1997 and 1998 Ultra came this way.

Interesting I guess thats why after drilling on the one i did i had to use 50 pilots!

 

[mxracer68]

At clutch engagement the needles are taking over ! Drop the needles one clip and see what happens... What year is the sled And is it an RMK? I just set a SKS Up with SLP Low RPM pipes 2.0 slides 50 pilots drilled the carbs to 1mm , 6CEY06 needles Q2 tubes and 380 mains runs like a top! I found the slp jetting to be a little funky

My needles are at the leanest setting. They are unmarked (assuming a version of SLP needles) and I have 247-p-4 brass.

I Really just want this thing to work better at low speeds in the bush, I have an EGT so I can keep an eye on midrange heat issues.

I appreciate all the chatter!

 

[800ultra]

You could try 2.5 or 3.0 slides!! I know back in 96 RMK on my ultra with SLP needles with 30 pilots 1.5 slides it was real blubbery down low ! cut my slide to 2.5 and made a big difference .. I think this 96 sks i just did with the 97 SPX jetting with 2.0 slides is the best setup i have used next to switching mine to XCR 800 carbs