A little more speed

[DTro]

Last night I was able to get out by myself in a few open areas and open er up a bit. On a groomed (pretty firm) trail, I was only able to get up to 60. I felt like it might have got possibly got 5mph more with another 50yrds and that was it.

I’m thinking that I should be able to get more out of my 2002 liquid cooled 488.

It sounds like it’s running great. But I will say that it seems to have a low to mid range lag. The belt engages great, but then if I get on it, the snap isn’t there. It doesn’t lug, but it doesn’t take off either. I can hear the RPM increase, then there is slight delay, almost as if something has a bit of a slip. Kind of like it feels when the track spins on ice.

I’m thinking maybe a clutch issue?

I don’t need to go that fast, but I also want everything to be working properly.

[broken_line]

somethings wrong.. my 340 jag will go 76 on a smooth trail/ ice on gravel road..

[BoxMN]

Yeah, my old '88 Indy 400 will still hit about 75 on a lake, with a little room, and I'm a fat guy

I am no mechanic, or sled vet, so not worth much use to you, but the track isn't too tight is it? I would guess not...

[Macgyver55]

HA! I figured once you got a little air under you that you'd soon be lookin for a little more power.

Your sled should easily be capable of more than 60mph. It sounds to me like it may be a clutch and/or belt problem. First, make sure it is the proper belt, dont assume that it came with the right one especially if you bought it used. Check it for proper width and where it rides on the driven clutch. When stopped it should be just slightly above the outside diameter of the clutch. Check the driven clutch for spring tension by turning and pushing on the inner half. Also, clutches should not be lubricated but they need to be clean to work properly through their entire range. I frequently use a compressor to blow excess belt dust and crud out of both clutches. If these things are ok, securely suspend the rear of the sled from a rafter or sturdy tree limb. While its suspended, rotate the track by hand and make sure it turns freely and the brake is releasing fully. Also check the track tension. Specs are different on different sleds, but generally if its hanging there should be maybe 1/2 to 1 inch between the track and the slides. Now you can start it and run the motor up through the full range to insure full movement of both clutches. If they are both moving fully through their range but it still wont go above 60 you may have other internal clutch problems like worn buttons or helix.

An air or fuel restriction problem isnt out of the question but you said it seems to run ok so check this stuff first and check back.

[DTro]

....more power

Thanks for the suggestions. I will look into all those those things.

I do seem to notice that it doesn't idle down very well when I stop (fast idle). Since I don't have a tach (who was the genious that put all the bells and whistles on this sled, but no tach? ) I cannot tell what it's at, but it does seem high. However if I blip the choke, it sounds much better.

I'll let you know what I find.

[gregg52]

not wrench guy here

but if you pull alot stuff alot i think that is hard on those clucthes depending on how heavy

but i pulled a fish once with a sled and it still went faster than 60 but always seemed like wayyyy more rpm s than speed

i tried new belt cleaning cluctch just was never the same

[Macgyver55]

I do seem to notice that it doesn't idle down very well when I stop (fast idle). Since I don't have a tach (who was the genious that put all the bells and whistles on this sled, but no tach? ) I cannot tell what it's at, but it does seem high. However if I blip the choke, it sounds much better.

Idle speed that drops with a blip of the choke could mean you have either a slightly plugged pilot jet, or a possible vacuum leak. If the carbs have not been cleaned recently that might be a good idea too.

[NAMASafetyDirector]

The correct belt is a 3211070 for that machine.

[ripstick]

Put a new belt on my 488 this yearand went from 60 last to ran out of room and had to let up 70 +. Still throttle left but who cares that fast enough.

[DTro]

Sounds like a good weekend project, thanks guys.

[Eelpout08]

definitly sounds like a clutching issue. before you dig too far into that though i would do a compression test and take a look at the plugs, should be a nice cardboard brown. best would be to do a shutdown at WOT and check then, also at 3/4 and 1/2 throttle, that will tell you if your running rich or lean.

when all that checks out take a look at the primary, spin the rollers with a small screwdriver or something and check for flat spots/excessive play, also take a look at the weights for the same things.

secondary should be checked for dirt and excess wear also.

the belt should be riding about 1/16 to 1/8 inch out of the secondary sheaves, should not be touching the primary sheaves and the belt deflection i think should be around 1-1/4 inches(correct me if im wrong)

also check the chain tension.

if that all looks good and nothing is binding or hanging up in the rest of the drivetrain its time so start swapping out springs and weights.

sorry for the long post!

let us know what you find

Edit- forgot to mention that you should wash a new belt in soapy water and let it dry overnight to get all the grease/molding agents off, you can also wash the clutch sheaves, just dont use anything that will scratch them

[rundrave]

just take the belt off, on the primary clutch draw a line down it with a marker and then reinstall the belt. Rev the engine and see if your getting full shift out the marker should be wiped off almost all the way to the top

if its not, start looking at your belt. if the belt looks good its probably your buttons which are known for going bad they just wear out after a while.

also, tinkering and fine tuning a CVT clutch can result in some great performance mods. A roller secondary and the right spring and weights in the primary will really wake up any CVT driven vehicle.

[Deep_Sinker]

Sounds like a carb cleaning is over due and I'd look at the clutch springs if the belt is within all tolerances; correct height in the secondary, correct off-set, correct width, etc. Look in your owners manual for this information.

[DTro]

Well I took a look at it this evening. Everything sure looked pretty good.

Plugs looked very good (didn't check compression).

Belt was right and looked good.

Track moved freely.

1 1/4" Belt Deflection

1" Track Deflection

Wiped the surfaces of the clutches off and blew out with compressed air.

Here's how it looked:

I guess I'll have to pull the carbs and clean those out next.

[Macgyver55]

I dont know how high you revved it but I never saw the belt travel all the way to the top of the drive clutch or to the bottom of the driven. Most likely you didnt run the RPMs high enough to go all the way. They do seem to move smoothly however.

I forgot to ask before, did the sled used to go faster, or is this the first time youve tried?

[DTro]

Didn't pinch it in that video, maybe 1/2 - 3/4 throttle

But yes, when I first bought it, I was able to get 75 out of it.

This all seemed to start to happen a couple of years ago, when I broke down and had to have the thing towed out a few miles (the intake hose breaking incident I posted about before).

I had the carbs out at that time as a small chunk of that hose had lodged into carb and made the float stick. So chances are it still has something to do with the carb.

[CASTnBLAST]

Could possibly be suspension or drive bearing issue, maybe that four foot jump in your earlier post finished an already worn component. The one with the most adverse effect would be the drive bearing. Remove the driven (rear clutch) and remove the bearing cover to inspect,usually three nuts. Sometimes when the bearing goes south the shaft actually will start wearing on the bulkhead (you don't want that) acting as a brake (you don't want that ether). To a lesser degree some of or one of the idler bearings could also be bad acting as a brake. While your under there check track tension,slides and make sure track is aligned you don't want the slides rubbing against the guides.

[BucksnDucks]

State wide speed limit for snowmobiles is 50 mph, i would hate to see this sort of activity condoned on this family oriented site!

[FasterThanYou23]

State wide speed limit for snowmobiles is 50 mph, i would hate to see this sort of activity condoned on this family oriented site!

LMAO!!!!

[leech~~]

Could possibly be suspension or drive bearing issue, maybe that four foot jump in your earlier post finished an already worn component.

I think your wife snuck a Governor on it one night to keep your air time down!

[jerkbait]

Could be the primary clutch. I thought I could hear the rattle of the weights when you reved it up. Pull the cover off of the primary clutch and see how loose the weights and inside peice are.