Thunder Products (Big Venom Viper kit) with Heavy Hitters

[murdered141]

Okay guys, finally satisfied as having a final set-up for my BV kit. Answer to my rev limiter issue were pretty well cured by switching to Gates C12 8dn equivilant. Biggest problem seamed to be slipping 8dn belt in the primary. My clutches were getting black bottom to top shortly after complete cleaning.

BV weight set-up: 1" set screw in heel, 3/8 aluminum + 2 thin washers middle, 3/8 steel + 2 thin washers tip.

Helix: Dalton 46/40 with BV blue spring wrapped 6-1. Can wrap 6-2 for off trail days.

Primary Spring: Yamaha Yellow-Pink-Yellow (softer engagement but slightly stiffer finish rate than stock Blue-Silver-Blue.

Nos-Pro rode my sled on Friday, and I got the thumbs up seal of approval.

Engine is all stock, but I do have a Sandale can.

Still tap rev limiter once in a while at hard launch, but only once occasionally, and sled really pulls through mid range. Great pull down low in the deep snow.

What are you seeing for top speed and rpm.

 

[SnoNinja]

Didn't do any speed runs as that doesn't really matter to me. Rpm were 8900-9000 on the clean road (with some track spin), and 8800-8900 on the trails.

 

[titanrcr]

I'm sure its on this thread somewhere I've obviously missed it if it is, I need some help, Im running the BV kit with 911 cover and OSP secondary adj on my 15 ltx Im still hitting the limiter quite heavily (on ice with quite a bit of track spin) on take off ,, I have the 1/4 and 3/4 set screw in the heel with Lonn's set-up in the the middle and tip, Do I need to do something with the weights or secondary spring position? or am I simply studded wrong? 144, 1.5" warthogs 1.25" lug. I'm pretty green when it comes to clutching......

Your 144 warthogs aren't going to hook-up on ice, they are just a trail stud. Don't change your clutching to cure this. How is it acting on hard pack?

 

[titanrcr]

I'm going to add that I did a lot of wrenching this weekend with my sled and can tell that if you lighten the tip too much (especially with a 153" 2.25 paddle track with the 8DN) you will get belt slip up on top.

These Vipers love tip weight and can tell you my setup with the 8DN belt was faster at 8,600 rpms than at 9,200

I tried different springs, lots of weight in the heel, less weight in the heel and more weight up top with the 8DN belt. For those who want a lot of pull on bottom end with awesome fuel mileage, put more weight in the tip and shoot for 8,600 rpm. The sled will sound low and laggy, but I could pull more mph and yank the skis at anytime. I used way less fuel than everyone else at our stop Saturday while heading to the I-500 races.

I like your findings here and totally agree that these engines should be clutched for 8600, both N/A and turbo. I'm seeing 8600 to 8750 depending on conditions and can get full shift out of my clutches. At 8800 I would be looking to get the rpm back down. Seems like most want to see 9000+ rpm, big mistake in my opinion.

 

[murdered141]

I like your findings here and totally agree that these engines should be clutched for 8600, both N/A and turbo. I'm seeing 8600 to 8750 depending on conditions and can get full shift out of my clutches. At 8800 I would be looking to get the rpm back down. Seems like most want to see 9000+ rpm, big mistake in my opinion.

Can you list your mods, track length and height, and gear's u r running.

 

[titanrcr]

Can you list your mods, track length and height, and gear's u r running.

Sure, Standard LTX-SE, 137" 1 1/4" Paddle, 144 trail studs, 6 lbs boost with 21/41 gearing. As NOS-PRO mentioned in his post, fuel mileage will be much better at that 86-8700 rpm area. I'm getting 17mpg with this setup.

 

[cannondale27]

I like your findings here and totally agree that these engines should be clutched for 8600, both N/A and turbo. I'm seeing 8600 to 8750 depending on conditions and can get full shift out of my clutches. At 8800 I would be looking to get the rpm back down. Seems like most want to see 9000+ rpm, big mistake in my opinion.

Use max recall feature. That's what I go by. Would love to clutch to 8600 but way more acceleration at 9000-9100

 

[titanrcr]

Use max recall feature. That's what I go by. Would love to clutch to 8600 but way more acceleration at 9000-9100

I am always watching the tach during an acceleration run to know what RPM I'm running but aside from that, dyno charts just don't support that you could accelerate harder running at 9-9100. Not to say that a well clutched Viper running at 9k can't out accelerate a poorly clutched Viper at 86-8700 rpm. Without using a performance computer or GPS based data logger there is no way to accurately gauge performance while clutch tuning. I have not done a thing to my clutching as supplied from Dave at Hurricane but certainly do trust in his opinion to run the engine at 86-8700 rpm and his ability to properly tune clutches for max performance.

 

[STAIN]

Sure, Standard LTX-SE, 137" 1 1/4" Paddle, 144 trail studs, 6 lbs boost with 21/41 gearing. As NOS-PRO mentioned in his post, fuel mileage will be much better at that 86-8700 rpm area. I'm getting 17mpg with this setup.

I am running the EXACT set up as you are with my own clutching. I also see 16-17 miles to the gallon. I am also following Dave's advice to keep it away from the limiter. I know a lot of times RPM=MPH, but squeezing a few mph's out on top isn't a huge priority for me.

 

[staggs65]

To add to that the butt dyno is usually inaccurate. When I was racing on timers my best runs never felt like much. The best setups are usually sneaky fast. I feel that's because our brains factor sound in to what seems fast

 

[titanrcr]

I am running the EXACT set up as you are with my own clutching. I also see 16-17 miles to the gallon. I am also following Dave's advice to keep it away from the limiter. I know a lot of times RPM=MPH, but squeezing a few mph's out on top isn't a huge priority for me.

There's no question that Dave knows his sh#t. If your'e seeing 16-17 mpg I'll bet you haven't blown any belts either. (proper belt side pressure)

 

[cannondale27]

Guys the few extra rpm isnt to add MPH. I agree 8800 is enough to get Max mph but it will take you longer to get there I am talking NA motor not turbo. Ulmer/Straightline was 9025 and Other was 9100 for max mph and acceleration. That leaves 225 rpm for over rev or error. Very easy to clutch within that margin and not hit limiter. The ONLY way to get accurate and consistent rpm reading is the recall feature. Its same everytime.

 

[NOS-PRO]

Use max recall feature. That's what I go by. Would love to clutch to 8600 but way more acceleration at 9000-9100

Not with these weights Cannondale, these Heavy Hitter weights seem to have more oomph on bottom and mid range when heavier in the tip. Belt slipping? Probably as I noticed the belt temps were higher.

 

[trevorl1]

I've got the evo stage 4, can and airbox mod.

I have one aluminum in the tip running about 9400+-.

How much more weight wood I add to bring it under 9000. I'll give it a try this week.

 

[NOS-PRO]

I've got the evo stage 4, can and airbox mod.

I have one aluminum in the tip running about 9400+-.

How much more weight wood I add to bring it under 9000. I'll give it a try this week.

Take the aluminum out and put a steel 3/8 with a thick washer in the tip. you won't believe the pull. Want more pull from 0-70, put in a 7/16 bolt in the tip.