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ultra 680 clutching / gearing question

13K views 37 replies 2 participants last post by  2001kx 
#1 ·
96 ultra sp 680 single pipe

i have just ordered a set of gears 20 / 39 1.95 ratio.
is this too much gear?(i dont have them yet to test)
i dont do much open riding...mainly tighter / hilly areas.

will i have to change the weights on my clutch?
right now it is all stock.

my sled is sluggish on the take off but from mid on up its not too bad.
 
#2 ·
20/39 was the stock gearing for the Ultra RMK.

Did you order a new chain, too? You likely have a 64W chain and will need a 66W to accommodate those gears.

Personally, I think you're going about this the wrong way... I would never start with changing the gearing because takeoff is sluggish. IMHO, you should be looking at the carbs, clutches, and belt long before you open the chain case.
 
#3 ·
well changing the gearing was cheap (19.99) so i thought i would give it a shot....Its not hard to change back if i dont like it.
if the chain isnt long enough i may just use the top (small ) gear to give me a 1.75 ratio...stock is 1.66
i am in the process of cleaning my carbs and seeing what i have for jetting...i will report back with my findings if i can get some jetting help as well.
when it comes to clutching it seems you need a engineering degree to figure out what you need -lol
the sled was $800 and i only rode 1 time last year in 5" of snow (thats the most we had last year on the ground) so im not really into putting lot of money into this thing.
 
#4 ·
You can use the top gear and still be ok with the 64W chain - it's definitely the bottom one that forces the need for the larger chain.

For jetting, your stock settings would be:
340 mains, 50 pilots, air screw out one turn. Those would be appropriate for 0-20 degrees at up to about 3000 feet elevation.

Other temps / elevations would require different jets.
 
#9 ·
And once the temp drops to the teens, it should be fantastic with that stock jetting (that's about what it's set up for). Right now, with the warmer air, you're running a little rich. Don't tinker with it, though, because you don't want to end up lean when the temps drop.
 
#10 ·
And once the temp drops to the teens, it should be fantastic with that stock jetting (that's about what it's set up for). Right now, with the warmer air, you're running a little rich. Don't tinker with it, though, because you don't want to end up lean when the temps drop.
ok sounds good...i will just clean the carbs and check to be sure i have the stock jetting...
It can be a little hard to start once warm and i will need to give it a little gas for it to start...hoping its just dirty carbs...we'll see.
 
#5 ·
For the clutching part... what's the engagement RPM? All of my sleds have always grabbed at 4200-4700 range, and that's generally about where they should be. If you ride different elevations, you may need to changes weights. But, changing the jetting shouldn't require it.
 
#8 ·
For me, it's just as simple to put in the Polaris SCL (Synthetic Chain Lube). A bottle of it costs about $15 and I've already done two chain case oil changes with it and have some left (Poo claims 9oz, but you'll never use anywhere near that if you go by the dipstick).
 
#11 ·
Hard starting, especially in cold temps, is sometimes caused by low compression.

What's your comfort level with carbs? Seasoned pro? Done it before but it's been a while? "Carb? What that?"

The reason I'm asking is because I can give you some pretty pointed steps to follow if you'd like for cleaning and initial adjustments. But, if you're comfortable with that already, I'll leave you to it.
 
#12 ·
im good with carbs...i do all my own work on all my toys but i just recently got into snowmobiling / working on them and its just new to me...
I just ripped the carbs off and cleaned them..the left side plug was black but the rest were a nice brown color so i assume i had some dirt in the 1 carb.
now im no master mechanic but i do like tinkering with things and am not afraid to get my hands dirty.
any advice you have would be welcomed regardless if i know some of it already...you never know and im always learning.
 
#18 · (Edited)
I think I should put all of this together as a sticky so I can just post a link to it... :)

Carb Cleaning:

- Unscrew the cover from each carb
- Remove the airbox
- Squeeze the clamps on the fuel lines at the carb end and slide them up on the fuel line
- Remove the fuel line from the carb
- Remove the air vent lines from the carb
- Loosen the collar around the carb boot
- Remove the carb from the sled
- Loosen the jam nut for the choke plunger and remove the plunger from the carb

- Tip the carb upside down over a bowl of some sort to catch the residual fuel still inside
- Unscrew the four Philips head screws from the bottom of the bowl and carefully tip the bowl away from the body (it may feel stuck initially, moving slowly will aid in preserving the gasket)
- Squeeze the clamp on the bottom of the trap line and slide it up, remove the plug from the bottom of the trap line (you should be able to see through the trap line at this point - if not, it's plugged and should be cleaned or replaced with a new piece of fuel line)
- Check the movement of the floats on the supports - they should move easily and smoothly. You can tip the bowl upside down and right side up repeatedly to test the movement
- Stand the carb upside down on a solid surface
- Use a thin blade regular screwdriver to remove the pilot jet
- Use a wrench to remove the main jet. There is a washer under the jet and the main sleeve is what the jet is screwed into - it should slide out through the top of the carb once the jet is off.
- Using a small point nail set or similar tool, press out the pin that holds the float arm in the towers. BE CAREFUL. The towers will NOT hold up significant force, and the pin will only go one way. You may want to rest the top portion of the "far" tower on something solid (leaving a gap under the head of the pin) and lightly tap the nail set against the other end of the pin if you can't press it out by hand. Again, BE CAREFUL. If you break either of the towers, you will need to buy a new carb body. Remove the pin and the float arm - pay attention to its orientation.
- There may be a spring retaining clip holding the needle in the seat. If so, carefully remove it then tip the carb over to get the needle out
- The seat is removed using a wrench
- Remove the idle screw (knurled end with a spring over the shaft that's visible)
- Remove the air screw (slotted end, almost flush with the carb body, near the idle screw)

At this point, you can spray out the carb and all of its passages with spray carb cleaner and compressed air. Or, if things look like they're heavily gummed up / dirty, you may want to proceed to "dipping" the carbs for a more thorough cleaning.

In order to dip carbs in heavy cleaner, you need to ensure that ONLY metal parts go into the dip. This will require that you remove ALL non-metal parts as follows:

- There is a very small, plastic cap on top of each of the float guides. These pop off, but be careful to hold your hand over them while lifting so they don't fly off and disappear. Remove the floats from the guides.
- Squeeze the clamp on the top of the trap line and slide it down. Remove the line from the bowl.
- Remove any and all rubber caps anywhere on the body of the carb.
- Stand the carb upside down on a solid surface. Using a thin blade regular screwdriver, carefully lift one area of the gasket. Using the screwdriver blade as a sort of 'shim', slide it carefully around the perimeter of the bottom of the carb, separating the gasket from the body as you go.

Set aside ALL of the non-metal parts (and the small retaining spring from the needle) and place ONLY the metal parts into the carb dip. You can remove the jet needle from the slide and put that in the dip as well. I leave them in for 12 hours if very dirty. When I take them out, I drain off as much of the carb dip as I can before putting the parts into a pot of hot water (150-160 degrees). I swish everything around liberally, rinsing out as much of the remaining dip as possible (which isn't much). Then, spray everything liberally with spray carb cleaner.

Use a small gauge wire to probe through as many of the carb openings as possible as well as through all of the openings in the jets.

Putting everything back together requires that you simply reverse the process. Set the air screw to the factory setting for your particular motor. Install the carbs back into the boots on the motor and tighten the band clamps to hold them in place. Screw the choke plungers into the bodies, but don't tighten the jam nuts yet.

Check the slides to ensure that the needles are inserted correctly, the c-clips are in the proper positions, and the cables are properly seated and locked in. Insert the slides into the proper carbs (cable length will determine this) and screw the caps down fully. The slides should only go one way, but the beveled lower edge faces the inlet side.

Now, you need to sync the carbs.

- You need to adjust the free play in the throttle so that there is about 2-3mm of play. This is necessary for the safety switches to function properly.
- With the kill switch engaged and the key off, zip tie the throttle wide open (or have a buddy hold it).
- Remove the airbox so that you can easily see and access the intake side of the carbs.
- Ensure that the slide is installed correctly with the cable inserted correctly into it.
- Ensure that the slide cap is screwed on all the way.
- Ensure that the top edge of the carb slide is -just- above the bottom edge of the carb intake throat. If it is not, adjust the cable on the slide cap until it is.
- Repeat for each carb.
- Remove the zip tie / release the throttle lever.
- Rest the solid part of the drill bit in the carb opening "the long way" and adjust the idle screw until the slide -just- comes in contact with the bit. This will give you a reasonable starting point for the idle.
- Once all of the carbs have been adjusted, slowly squeeze the throttle and ensure that all of the slides begin to move at exactly the same time and go up exactly the same amount.
- Adjust the air screws according to the manufacturer's setting.

Now, adjust the choke plungers.

- Get a thin gauge piece of solid wire and bend it at a 90 degree angle about 1" from the end
- Remove the airbox so you can easily access the intake side of the carbs
- Apply the choke
- Slip the bent section of wire into the enrichment hole on one carb and release the choke - make sure that you can not easily pull the wire out
- If the wire comes out easily, you need to screw the plunger adjuster into the carb body until you feel it contacting the wire and keeping it from moving
- Screw the adjuster in another half turn from that point and tighten the jam nut
- If the wire does NOT come out easily, pull on the choke lever until you feel tension in the cable - you should only have to move the handle a small amount after you feel tension before you can remove the wire
- If, after lightly applying the choke, you still can't remove the wire, you will need to unscrew the plunger adjuster from carb body
- Unscrew it until, with the choke off, you are able to remove the wire then use the process above to adjust it correctly

- Re-install the airbox

You're now ready to start the sled and tweak the air screw and idle settings until it's where it needs to be.

While you're in there, you may want to check compression. Here's my process and follow-through:

Pull the plugs and set them aside. Make sure the sled is off and the motor is completely cold. Connect the gauge to a cylinder, hold the throttle wide open, pull (or crank the E/S) until the needle on the gauge doesn't climb any more.

Repeat for all cylinders.

Unless you know that your gauge is accurate, you might want to do a compression test on a machine that's "known good". Gauges do vary, and sometimes read too high or too low.

If you know your gauge is good, I would recommend the following courses of action:

- 120+ per cylinder: Go ride.
- 110-120, be aware that you aren't getting max performance, go ride.
- 100-110, be aware of your motor and heed any noticeable changes in sound or performance. If it's the off season, tear down the top end and freshen it up. If it's during the season, you can keep riding knowing that your performance is sub-par. Don't "push" it too hard.
- 100 or less, freshen the top end before something breaks and it ends up costing you a lot more money to repair.
 
#21 ·
here are some pics of the clutch i have on my sled...trying to figure out what puller i need to get it pulled.
like i said before my old puller that pulled off my original 96 ultra sp clutch will not work with this clutch...the hole is too small for the puller to fit in.
the hole size is approx a little over 1/2" in dia.
any ideas?
 

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#22 ·
I've read a number of threads where people use a 5/8" bolt, appropriate thread pitch, and pack the center with grease. Tighten the bolt, wait, tighten, wait, etc. Eventually, it pops off. I'm sure you could search and find at least a couple of posts about how to do it.
 
#24 ·
Dunno... I guess it depends on the specific clutch. If you go the home made route, get a Grade 8 bolt and match the threads (whether metric or US). Or, spend $30 and buy one.
 
#25 ·
ok well i just called my local dealer an he said as long as it comes off easily he will pull it and shim it for $30-$40...
so i think i will just do that to save me the headache of finding the correct bolt + it will get shimmed and sould help my bottom end performance i hope.
 
#29 ·
Any time you tear down a clutch and service it, it's a good idea to have it rebalanced. The question I pose is this: Is your dealer properly equipped to do the work the right way?

You also need to be sure that you shim it to a new drive belt so that it's set correctly, and if you're going to have it all apart, is that a good time to do the spring, weights, buttons, and rollers?

You might want to pop the thing off and send it off to have it rebuilt and rebalanced.
 
#30 ·
well i got my gears today and they are junk (see pic)
the guy said they were in good used condition - yeah right.
so i was a little bummed and i just put it all back together with my stock gears and took her for a ride.

WOW what a difference...she fires right up now and runs incredible..
pulls hard from bottom to top.
all i did was clean carbs , took top boots out of airbox and took apart & cleaned the secondary clutch...
Its like a new sled and it has never ran this good..easily 2x the power it had before...
Im glad i didnt do the gears and really dont see the need for them now.

also clutch engagement is around 3700 rpms..
 

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#31 ·
First, I would suggest that you absolutely go after whomever sold you those gears. That gear doesn't even qualify as "Used", let alone being in "Good used condition". It's broken, plain and simple, and is unusable. It's scrap.

If you bought via PayPal, and have any documentation of your transactions where the seller claims they are in "Good used condition" go back and ask for a full refund. If he balks, respond and give him 24 hours to agree or you will submit a claim to PayPal with the documentation.

Glad you took the time to clean the carbs and see an improvement. I feel that your clutch engagement is too low and will ultimately rob you of top-end speed. You should consider having the primary rebuilt and/or replace the spring.

Third - on the airbox... What is it that you removed? And, have you tried putting that stuff back in? I'm a fan of keeping the airbox very clean, but I don't advocate for gutting it or removing pieces. That box is there to keep snow out of your engine, and removing parts of it could defeat that function.
 
#32 ·
im a powerseller on ebay (decal business) so i do know ebay / paypal very well :wink:
im working with the guy now to get my money back.

I think what im going to do is finish the winter on this clutch then have it rebuilt during the summer as well as getting my shocks rebuilt.
any idea on how much a clutch rebuild should cost?

for all i know maybe the tach is off on the sled?
i just took off the rubber boots on the top airbox...I will put them back in and see if it even makes a difference (doubt it will)
 
#33 ·
Everything I see in the Polaris service manual says that the clutches should engage around 4200-4300 RPM. What's more important is that you don't exceed the max rated RPM for your motor. In your case, that's 8200 RPM. If you're not seeing max RPM in that area, then you're definitely engaging too low and would benefit from having both clutches looked at (possibly rebuilt).

I don't know the cost you would be looking at because there are variables... Weights, bushings, spring, etc. as well as whether or not you would also have it balanced and possibly shimmed. I do know that if you're not engaging at the proper RPM, you run the risk of blowing the motor (engaging too high and over-revving), losing power (engaging too low), and causing abnormal belt wear.

If you are off, it doesn't sound like you're off by a lot. If it were me, I would watch it to see if it appears to be changing at all as the season wears on. It could be worn and needing some attention but perfectly capable of getting you through the season.
 
#37 ·
If you're looking for used parts, there's stuff all over the place (including Craigslist and eBay to name a couple). Look for someone that parts sleds and knows what they're doing when it comes to Polaris. If you're dealing with a guy that doesn't understand subtle differences in models (like a 97 440 is NOT the same machine as a 97 XC 440), you're going to end up with a lot of wrong parts.

The cables are one piece and do not come apart. Part number 7080597. Looks like it's roughly a $30 item.

For the potential to get used parts, you can try alssnowmobile.com or hudons.com. I've personally bought from Al's and have no complaints other than it's important that YOU know the part number of what you're looking for because their model cross-reference isn't always complete. My only gripe with them is that the shipping cost is high.
 
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