Boosted sled top speed on snow? Clutching advice needed

[kinger]

I'm questioning the top speed of my sled on a good lake. All weekend I could only muster around 108-110 mph on the dream meter and once I hit 116mph.

On a very hard pack road I can go much faster and once last year saw 156 on the dream meter.

The lakes we were running were decent hard pack to soft snow and a new 800 Etec XRS was right with me in the same conditions, I thought I should have been able to blow by him?

My gearing is 25/38 so one tooth taller the stock, 121" cobra 144 studs, dual carbides, slydog powderhounds, RPM was 10,500-10,800 boost 10-11 psi

Wondering if the gearing is too tall which is odd because my old RX1 with the same gearing and at 9800 rpm (clutched for nitrous) on stock motor would hit about 108 mph on the dream meter, in similar conditions.

I dont care about absolute top speed but I want to wax 800's no matter the conditions!

Thoughts?

 

[Schlick55]

Might want to call Acme Rocket Co., it worked for the Coyote

 

[kinger]

LOL you get that xtx out at all???

 

[jsjk-4-stroke]

i have a 05 rx1 136 track i use 25/38 gears and it will rip your arms off running 7 1/2 lbs i ran 800 etec 800 r once we start i never see them , you should do better than me at 10 lbs , maybe you have to move weight around in clutches , mine is 2 tung in heel 4 washers in tip i pull 10100.
just a thought ........25/38 is great

 

[mbarryracing]

kinger,
Are you sure your not coil binding on a spring or something in the clutching? Are you getting full shift out?
Reason I ask is just because youre at the right RPM and boost level doesn't automatically mean that youre transfering that power to the ground...
We had a race sled that would pull the right RPM but the clutches wouldn't shift out due to binding so the sled wouldn't MPH... You should be doing "the owl" looking back at that ETEC at 10 lbs... I walked by one at 3/4 throttle just toying with him. Of course, mine is a turbo and not a SC, LOL!

 

[Habich76]

Time to get the felt tip pen out and mark the primary sheave! Sounds like it is asking for more weight or less helix angle

 

[kinger]

I am a clutching idiot I have never even attempted to mess with them simply because I dont believe I would leave it alone after that. LOL

I sent both clutches off to Ulmer this spring and he re did all the buttons, rollers, new spring, etc. Anything that was out of whack.

Draw a line on the primary sheave and see how far down it goes? What is good and what is bad? Sorry I'm a newb on this.

 

[machz69]

Kinger, what are you running for primary set up?

 

[YamerHammer]

On primary sheave the clutch on the motor.....just leave the belt on and draw a line on the side of it strait up and take it for a rip and try and get as much top end as you can and come home and see how much line you have left on the top bit of your clutch and that will tell you if you are shifting out all the way or not. Least line the better. If you have spring bind you will know it, there will be quite a line left. Just from changing a gear like that there is no way you should see 1600 - 1700 rpm loss....there is something else you are missing. It should just come down to taking a washer or 2 off the tip of each weight.

 

[Fergie]

it has to be in your clutching, something is binding. I see a consistant 140mph on the dreamometer with cpr only set up to run 12psi with stock gearing. keep checking your clutches.

 

[pro116]

Are you shure you don't have any bearings shot.

 

[kinger]

I'm running ulmer clutching I think its super tips. I dont have a clue how much weight.

I blew a belt this weekend in 300 miles of riding, it was a old belt 4 yrs old 2700 miles so it was probably time but I deglazed it and checked it before the ride and it was fine.

I adjust the helix to a steeper angle by 4 degrees to get the RPMs up.

Fergie your getting 150 on Dm really no matter the snow conditions? I'm talking lake not a hard road. For mine anyway there seems to be a difference.

Pro116 - I went through all the drive bearings this year and can spin the track freely by hand. I didn't replace them but I cleaned and greased them while they were still in place.

Thanks for the help!

 

[pro116]

I'm running ulmer clutching I think its super tips. I dont have a clue how much weight.

I blew a belt this weekend in 300 miles of riding, it was a old belt 4 yrs old 2700 miles so it was probably time but I deglazed it and checked it before the ride and it was fine.

I adjust the helix to a steeper angle by 4 degrees to get the RPMs up.

Fergie your getting 150 on Dm really no matter the snow conditions? I'm talking lake not a hard road. For mine anyway there seems to be a difference.

Pro116 - I went through all the drive bearings this year and can spin the track freely by hand. I didn't replace them but I cleaned and greased them while they were still in place.

Thanks for the help!

Kinger to get your rpms up you should put the helix angle shallower not steeper.This is not the correct way to adjust the rpms.The helix will work in a pinch for elevation changes but you should really take some weight out of the weights if you need rpm.I have seen with running really agressive heix or high angles a major loss of rpm when gearing up.

 

[kinger]

That is what I was doing was adjusting the shockwave just to get the RPMs up but your right its probably shallower I mispoke. All I know is you go clockwise on the shockwave it raises the RPM LOL

On the 25/42 gearing ulmer set that up for me on the dyno/snow at his shop the RPM was dead nuts and 3 years on same belt it would just slam into 120 mph and run out of gear so that is what started this is trying to get 140's mph on the DM on snow or ice.

Now I messed it all up. HAHA I'll probably investegate taking more weight out of the primary get the helix back to where it was. i just dont know where to pull it from tip, heel, mid, etc.

I got a call into ulmer this should be a pretty standard set up so hopefully I dont have any trial and error with low snow when I do find some I just want to ride. That or I'll put the 25/42 gear back in.

 

[Fergie]

140 & this is on a lake with hardpack minimal snow cover. i can't recall anytime that i could not hit at least 125mph. 4 years & 4000 miles & the best i've seen is 146.