Top Speed Stock - Snowmobile Forum: Your #1 Snowmobile Forum

joezak111 · 10-19-2004, 11:44 AM

Just wondering is the top speed of some sleds out there.
Please specify speedo or radar reading and what mods does the sled have if any.

2000 polaris 600xcsp - 125mph (speedo)
2004 viper 700 - 121mph (digital speedo)
1990 ski doo mach 1 583 - 95mph (speedo)

dano · 10-19-2004, 07:53 PM

99 rmk 700 106mph on the speedo before i put on the 141x2. Now it goes 96mph, speedo

not sure what the 800 does yet, but as soo as i find out as will you

chase9119 · 10-19-2004, 08:27 PM

2003 MXZ REV Sport 600HO (stock) - 107mph(Speedo)
1997 XC 600 *tripple* (stock) - 102mph(Speedo) with 144 picks

Both topped out on hard packed powder snow in optimal temps. Around 10 degrees F.

Buddy had a 1998 ZR600 *Fuel Injected* (stock) - 99mph(speedo) with a 1.5 inch paddle track. (this was about a month before his CDI went out, so this may have effected the top end slightly.?.)
His wifes sled 1997 or 99??? ZR500 *FI.* (stock) - 90mph(speedo) with 96 picks

*disclaimer* These are all speedo readings, which as you know are higher then actual!

G-ForceJunkie · 10-19-2004, 09:35 PM

daktruckie99 · 10-19-2004, 10:17 PM

mine tops out around 90 on the speedo, but after what I did this summer ill be lucky to see 80+

rgoers · 10-20-2004, 10:23 AM

Haven't had the room, or opportunity, to TOP out... but I do know that when my speedo said almost 80, my GPS had logged a max speed of 68.

Speedos aren't known for their accuracy, so don't take those numbers too seriously. After all, they're only measuring drive shaft revolutions, nothing more.

adrenaline · 10-20-2004, 10:37 AM

this is the difference in speed I saw last year depending on temperature.

95 mph @25F
115 mph @ -20 F

both are speedo. I know temp makes a difference but I was surprised at the big difference.

rgoers · 10-20-2004, 11:28 AM

Quote:

Originally posted by adrenaline
this is the difference in speed I saw last year depending on temperature.

95 mph @25F
115 mph @ -20 F

both are speedo. I know temp makes a difference but I was surprised at the big difference.

Wonder why it would be faster at lower temps. Is it an engine issue, or just the fact that the snow pack would be much more solid?

G-ForceJunkie · 10-20-2004, 11:50 AM

every 10*F drop in temp you make another 3% hp

that, plus the harder pack probably

Billdog350 · 10-20-2004, 12:03 PM

Unless you rejetted...the colder, denser air is leaning out your motor and thereby producing more peak power...thus higher top end.

If you jetted properly (leaner) for 25 deg....you should get closer to that 115 mph top end.

rgoers · 10-20-2004, 12:10 PM

Quote:

Originally posted by G-ForceJunkie
every 10*F drop in temp you make another 3% hp

that, plus the harder pack probably

Cool! So, like, if I was riding my 1980 Jag (@30hp) in Antarctica, and it was, like, -60F outside, I'd have almost 20 more horsepower to work with? Let’s see… now, adjusting for the extra weight of my frozen butt, I think the horsepower advantage would get cancelled out somewhere in the math. Not to mention; you couldn’t drag me outside to get on a sled at –60 (unless I was dead, and in that case, riding it wouldn’t be much fun… would it?).

All kidding aside, that’s an interesting fact. Is it the ambient air – or (I’m assuming) the temperature of the intake air?

adrenaline · 10-20-2004, 12:39 PM

Quote:

Originally posted by Billdog350
Unless you rejetted...the colder, denser air is leaning out your motor and thereby producing more peak power...thus higher top end.

If you jetted properly (leaner) for 25 deg....you should get closer to that 115 mph top end.

my sled has DPM, should take care of jetting itself. Runs great at all temps on the trails, only big difference is the top end with temp. changes.

G-ForceJunkie · 10-20-2004, 12:56 PM

Quote:

Originally posted by rgoers
All kidding aside, that’s an interesting fact. Is it the ambient air – or (I’m assuming) the temperature of the intake air?

It would be temp of the intake air, guys at the strip ice their intakes all the time to cool the air coming in.

and FYI, I'm not 100% sure it's 3% for every 10*F drop, but I'm about 70% sure, if you really want to know, google is your friend

on a carb engine you'd have to adjust your jetting to make sure you were getting enough gas (since your getting more OXYGEN-air)

Billdog350 · 10-20-2004, 07:32 PM

Is DPM fuel injection or just timing adjustment? I'm 90% sure its just timing so it won't "fully" compensate for a lean condition. While you might not blow up your motor...it will still be running lean.

adrenaline · 10-21-2004, 10:37 AM

The motor is carbed. I believe the DPM (digital performance management) adjusts jetting automatically depending on pressure and temperature.
If there is any malfunction it's supposed to go to the full rich setting to save the motor.

Billdog350 · 10-21-2004, 12:34 PM

Ok, that is NOT jetting. I agree that it will save your motor, but all it does is change your timing (which will richen or lean out your mix in a way) but it WILL NOT change your MAIN JETS which regulate how much fuel enters the motor.

I still believe that your motor AFR (air fuel ratio) is leaner at -20 than it is at 25. As a result you have more power...and thus more top end.

Smallengineguy can you comment?

**Administrator** · 10-21-2004, 01:32 PM

99 Zr 500 EFI = 102 MPH
--> I couldn't believe it either, but yep the 500 made it into three figures. Cold day, really hard packed.

2002 Mountain Cat 600 EFI (136" w/ 2" Paddles) = 90 MPH
--> Changed clutch weights, but left 9000+ foot elevation gearing in the sled. Great low end power, not too fast after 70+ MPH.

adrenaline · 10-21-2004, 02:13 PM

DPM adjusts carburation for Ideal fuel air mixture. It does nothing to timing as far as I know.
The RER adjusts timing to make the engine run in reverse.
Apparently even with dpm, the extra cold air improves engine performance.

Billdog350 · 10-21-2004, 02:43 PM

You are right, I just looked up Ski-Doo DPM. It is basically a digital version of dial-a-jet.....they have a digital altitude compensation set up (adjusts fuel ratio) which probably also factors in temperature. Though you aren't changing your main jet.....it is compensating by allowing extra fuel at different conditions...basically a mix of EFI and plain carb.

I apologize, I am wrong and you are right....I hate when people don't admit when they're wrong...and I was wrong.

adrenaline · 10-21-2004, 03:18 PM

No problem Billdog, had to look it up again myself.
Where in Ct are you from? I'm in East Hartford. Do most of my riding in Pittsburg, NH.