terrible top end speed..

[connor wilson]

hey guys, just got back from a weekend riding, my sled is a 16 ltx se big venom clutch kit, mbrp race can(being removed shortly was to loud) and a 8DN belt, pulls really good in the trails, corner to corner the sleds an animal, but top end its terrible 135-140kph i feel like the sled was faster before the clutch kit, any thing i might be missing? the sled is running around 8800 rpm at wot

now on previouse 2 stroke sleds i ran, i have tested cans and the mbrp can always made the sled run slower then the stock muffler, could this be whats holding the sled back? not enough back pressure maybe? the sled pulls amazing then literally hits a wall at 135kph


thanks
connor

 

[09nytro]

I'm in the same boat ... sandale muffler and did air box mod on here ... nothing ... left muffler on and put air box back to stock ... thinking about putting in 21-41 gears

 

[RTX]

hey guys, just got back from a weekend riding, my sled is a 16 ltx se big venom clutch kit, mbrp race can(being removed shortly was to loud) and a 8DN belt, pulls really good in the trails, corner to corner the sleds an animal, but top end its terrible 135-140kph i feel like the sled was faster before the clutch kit, any thing i might be missing? the sled is running around 8800 rpm at wot

now on previouse 2 stroke sleds i ran, i have tested cans and the mbrp can always made the sled run slower then the stock muffler, could this be whats holding the sled back? not enough back pressure maybe? the sled pulls amazing then literally hits a wall at 135kph


thanks
connor

14 rtx
im running the evo stage 4 reflash with header, muffler and airbox mod. and big venom kit
I dropped 1 tooth on the bottom gear so its 24/48
my best speed with this setup has been 103.
before the big venom install it was 93 with cotc kit and stock gears
with all stock it was 85

 

[rbell14]

Same boat, expected more top end with Big Venom Clutch kit. I have Ulmer can and Airbox mod. I hit 9150 RPM's and max speed is 83-85mph. Obviously conditions play a big role here but I think these sleds are limited by gearing. 0-85 pulls hard but then nothing more on top end. Have not tired on good hard pack yet.

 

[Ding]

Not really knowledgeable about these sleds, but are you guys really shifting all the way out?

Edit: Just because rpms climb doesn't mean full shift out of course . . .

 

[TD Max]

I've messed with 3 different clutching setups so far in various different configs:

1) Ulmer
2) COTC
3) Big Venom

I keep coming back to the Ulmer setup. Neither kit shows major top end differences, but the Ulmer has much better bottom end hit. I don't see 9,000+ working for me. Revs and goes nowhere on top. Gearing will have an impact, but how much low end do you want to sacrifice? Cannondale geared very fast and as I recall did not gain a ton up top plus he lost low end.

 

[rbell14]

911 cover allows for fine adjustments on primary so you can get easy smooth engagement at low rpms. Secondary in the Big Venom kit allow for no binding either. Deflection was set perfect on a new belt and after breaking in the belt this is still max 85MPH. Granted on a ice lake I could probably go faster but on decent normal trails 85MPH. I even ran my old belt with proper adjustments just to compare, same results (belt had 2,000 miles on it. )

 

[RTX]

911 cover allows for fine adjustments on primary so you can get easy smooth engagement at low rpms. Secondary in the Big Venom kit allow for no binding either. Deflection was set perfect on a new belt and after breaking in the belt this is still max 85MPH. Granted on a ice lake I could probably go faster but on decent normal trails 85MPH. I even ran my old belt with proper adjustments just to compare, same results (belt had 2,000 miles on it. )

from what I have seen, 83 -87 is my average top end in most every conditions.
the exception to this would be running hardpack or ice. then I get a decent top end.
I don't think you will ever be able to consistently run 100 mph in all conditions without major gearing changes and it will absolutely result in terrible low end performance.
my goal is to get a consistent 90mph no matter what the conditions are, so I have some more gearing changes to try out.
I am sad to say it, but for the most part I have begun to accept that this is an 83-87 mph sled.

 

[yzf1999]

Ok guys here's my story...2015 LTX SE all stock it would not go faster than 86 to 88.
This summer I installed Ulmers clutch kit with soft start spring , trail can and an Excell air intake. Also added DuPont sliders and a 4th wheel kit...now it pulls like an 800. Now it totally blows away my buddies 2015 LTX spring order edition from start to wide open which is now a constant 95 mph....I'm happy as a clam now!!!

 

[sxr70001]

I guess I should feel pretty lucky after reading this thread. I hit a 101 on a road and 97 going across the lake this weekend. Going up past 90 is pretty easy in most conditions if I don't chicken out first.

This is just my opinion, but i think getting the coil bind out of your secondary is one of the biggest factors to not hitting that wall. I have a Dalton helix and the thunder products secondary spring in addition to the rest of the mods in my signature. All in all for trail riding it's fast enough for me anyway, but I know we all have different goals.

 

[Studroes144]

If you guys want to do some reading I have a 3 year old post in the FAQ at the top of the page. Track/slide drag. I too was cursed with top speed issues which everyone pointed fingers at clutching..after putting on new slides, an extra set of bogey wheels and loosening the track up on mine I gained back every bit of mph that was missing. With duponts, an extra set of wheels and a clutch kit my sled would run 102-104 mph every time that conditions allowed with me riding it at 240 pounds. Clutching may be your guys issue but after a few years of owning this sled I can definitely say it's a sensitive chassis so any little thing you can do to free up some rolling resistance will help.

 

[sxr70001]

What Studroes said too, I have all that probably because I read his posts back then. My limiter straps are pulled down one hole too. I weigh over 250, so it's not like there's not enough power. Maybe us big guys are compressing the chassis more? One thing for sure this sled has been a mystery from the start, so much variance from one to the other.

I do know for a fact though that I had my helix shimmed out and then Cannondale noticed that it could cause problems so I took out the shims and lost about 7 miles and hour. After I got a new secondary spring and helix I got the speed back.

I think another thing that kills us is perception because our speedometers are so accurate. A good example is all weekend my friend who rides a Venture was telling me "man you are flying, I was going over a hundred and still couldn't keep up". When I told him I never went over 90 he said no way!

 

[Studroes144]

What Studroes said too, I have all that probably because I read his posts back then. My limiter straps are pulled down one hole too. I weigh over 250, so it's not like there's not enough power. Maybe us big guys are compressing the chassis more? One thing for sure this sled has been a mystery from the start, so much variance from one to the other.

I do know for a fact though that I had my helix shimmed out and then Cannondale noticed that it could cause problems so I took out the shims and lost about 7 miles and hour. After I got a new secondary spring and helix I got the speed back.

I think another thing that kills us is perception because our speedometers are so accurate. A good example is all weekend my friend who rides a Venture was telling me "man you are flying, I was going over a hundred and still couldn't keep up". When I told him I never went over 90 he said no way!

I'm a bigger guy and my sled has always went faster with me on it, got buddies that are 100 pounds lighter and the sled is slow with them on, hit the nail on the head, suspension needs to be compressed to get better speed. These things can gain so much just by focusing on the chassis.

 

[Wannaviper]

I don't understand the inconsistency and lack of top speed in some of the Vipers. I am 250+ with gear, and I am riding a new this year 2016 XTX that just turned 700 miles. This weekend my speedo hit 91 and the GPS was 89.9 mph in one long uphill pull. It would be nice to hit triple digits, but honestly, I am very happy with my XTX and I have done nothing with clutching, belts, etc.; everything is bone stock and right from the dealer showroom. I have a 2015 LTX DX that I added an OSP clutch adjuster and a 4th wheel kit, and last year my top GPS speed was 96.7. Even tough the XTX is geared lower, it seems to be getting stronger every ride, and I would not be surprised to see it hit low to mid nineties before the end of the season. I am very happy with my Vipers!

 

[willyswagon]

2015 STX-DX, just about 2200km(1400 miles). Sled is stock with the exception of a 4th wheel kit, 250 dressed.
The best I could get out of it last year was 140km/h(88mph). Softened up the skid this season and slacked the track off just a hair after a buddy pointed out that it looked a little tight to him. I was out for a 225 mile run last week, and hit 150 kph(94mph). The speedo is bang on accurate with the gps.

Fat guys with long tracks seems to be where the speed is!