Not getting full shiftout

[TestMaster]

Everyone who has used a GPS to validate the speedo has reported the GPS and speedometer are in sync within 1/4 MPH. Can't get better than that, probably as good as radar gun verification.

That GPS verification was based on at least 8-10 Viper/GPS combinations. Done a lot of statistics in the last 35 years and I'm really impressed by the lack of variability by those that have reported.

 

[NOS-PRO]

my GPS was within 1 mph of what my gauge was reading.

I used to cut 2 teeth off of my apex speedo gear to make it correct at 125.

 

[Studroes144]

When doing the clutch testing on my viper one run the top speed on the sled was 96. Stalker radar gun showed 96.4.

 

[Yamadog]

The speedos are arctic cat not Yammy dream meters. I am seeing within 1 to 2 mph diff with GPS

 

[cannondale27]

Same here. I hit 98mph with 300 mi on it loose snow on a lake and not even close since. I hope you are right studroes I will pull up limiter straps and see tomorrow. Should hit 1000 mi tomorrow so happy with that

 

[Studroes144]

Same here. I hit 98mph with 300 mi on it loose snow on a lake and not even close since. I hope you are right studroes I will pull up limiter straps and see tomorrow. Should hit 1000 mi tomorrow so happy with that

To me it seems kinda crazy that something like the slides dragging could affect the sled that much but it's really the only thing that makes sense. My sled as well as many others by the sounds of it, started out putting up some really good speeds. Mine has gradually been getting slower and nothing is changing as far as performance. I did get to really inspecting my slides the other night and where they are worn on mine is about 2/3 back on the rails and it's just a gradual hump taken out. I've been told since I seen that that something like that will affect speed big time because the track will follow the wear patter on the slides and at higher speeds the track will get a wave effect which kills all momentum. On just gonna bank on this being the problem and invest in DuPont slides and extra wheels. Gonna put extra wheels on the front bend of the rails and then 2/3 back on the rails. Sled it still a rocket to 60 and after that it hits a wall. Seems to me like once the sled settles back down and gets planted on the ground is when it really loses all momentum. For anyone not seeing 90+ mph speeds in good conditions I'd start inspecting your slides and consider doing something like this

 

[larrypolaris]

Hit 102 yesterday on a hard pack road. Engine was spinning 9000-9100 rpms.
Seems like the Vipers can hit the 3 digit mph, but on ideal conditions.

Add some loose snow conditions and you drop mph.

In heavier snow earlier on the day I only seen 85 mph.

I think the sled just needs more HP to help it get over the edge when the snow gets loose.

Can't wait for the Excell header dyno results.

Raced my buddy's Nytro with header Skinz muffler & clutch kit.
We raced from a role on that hard pack road. We were neck & neck. But he had a bit more top end.

 

[cannondale27]

I think you are right. Just need hp it never ends eh! Ulmer told me to pull the airbox and look for velocity stacks that are folded over. Could be. Seems more likely that we are just dealing with a sled that was clutched really well from factory and the conditions this year with all the dry snow that doesnt pack requires more hp to make big gains.

No biggie I am very happy with my clutching from Ulmer and how easy it is to change for anything I need without drillin rivets out. Best of all I have yet to be beat by anyone in a short drag race. Really that is what I bought this sled for. Corner to corner and instant acceleration with hookup. I will have another teardown of hood and airbox real quick here and hopefully dont find anything wrong with velocity stacks. Sure seems that some hidden hp is awaiting us. Intake temps are very high she needs cool air I think and the exhausts out there sure look promising !

 

[davey]

I was wondering if the 4th wheel kit would help top speed. Seems like when I turn at all the track cuts in and fills the rear skid with snow and then I feel a drag. So I was thinking with the 4 the wheel if that sorta works as a blocker to keep the rear skid from loading with snow. Just a thought.

 

[cannondale27]

Not sure. That was the one mod I did before I ever rode it.

 

[Studroes144]

I was wondering if the 4th wheel kit would help top speed. Seems like when I turn at all the track cuts in and fills the rear skid with snow and then I feel a drag. So I was thinking with the 4 the wheel if that sorta works as a blocker to keep the rear skid from loading with snow. Just a thought.

The 4th wheel kit on mine made a huge difference keeping snow of from there. I have no snow flying up and no ice build up at all. If you are running studs on the outside lugs the extra wheels help a lot with traction as they drive the studs hard in the ground.

 

[Studroes144]

I agree with Steve aswell that intake temps are very high. The aftermarket exhausts have all proven to have great gains. Some are seeing 10hp increase with a simple muffler swap. Add more intake airflow and these will be a nasty sled! Def will have the extra hp then to get over that hump.

 

[NOS-PRO]

Well Steve, welcome to the 100mph club!!!!!

 

[TurboJamie]

Not sure what the op was expecting. Yamaha clutches do not shift the belt to the top of the sheve. Were also dealing with a 130 hp sled, with big tall suspension and a big track. Imo on a stock viper 90/100 conditions dependent is pretty good. Guys need to pay zero attention to the " my sled does 105 something is wrong with yours" type comments. Conditions conditions conditions! The only thing that makes mph day in and out on soft trails is turbo power.

 

[NOS-PRO]

Not sure what the op was expecting. Yamaha clutches do not shift the belt to the top of the sheve. Were also dealing with a 130 hp sled, with big tall suspension and a big track. Imo on a stock viper 90/100 conditions dependent is pretty good. Guys need to pay zero attention to the " my sled does 105 something is wrong with yours" type comments. Conditions conditions conditions! The only thing that makes mph day in and out on soft trails is turbo power.

Well said..... everyone has different snow conditions and different setups.

I did my own clutching to mine and very happy with "my" results.

Trial and error, that is the key.