Viper fuel Mileage Woes.

thegrizzly1

thegrizzly1

Previous sleds:
Joined
Jan 6, 2009
Messages
56
Age
50
Location
Chisholm Mn.
I'm still having poor fuel mileage (7.5 MPG on a good day) with my viper and I'm looking for a little help.

I have an 03 Viper Mountain I purchased and put back to stock as much as possible. I purchased and put back on stock exhaust, went back to factory jetting and clutch weights (low altitude). All powervalves are rebuilt, cables are all new, and they are adjusted properly. I have 21/40 (non reverse) gearing with 8tooth extrovert drivers. I am running a 144"x1.25" ripsaw track. I have gone through all driveline and skid bearings and bushings, and I am confident I am not having a mechanical drag issue. The only drive item non stock is the TSS-04 secondary. Both clutches are clean and in good condition. The engine runs great, I am getting full RPM, backshifting seems spot on. The sled runs great, just gets poor Mileage.

When I cleaned my carbs this year, I pulled my reed cages thinking my problem had to be reeds. I could not find anything chipped or broken. They seemed to snap back just fine and seal. The one thing I noticed is that they are carbon fiber. I thought all my redhead triples had steel reeds. What do the vipers come with from the factory? I was always under the impression stock steel Yamaha reeds were fine for anything but a heavily modified engine? Is there any chance the reeds are causing my poor mileage? I know I used to get 12 MPG with a stock 2000 MM700 with the paddle track on it. I would think the viper should do just as well if not better with the ripsaw on it.

Any help is appreciated.
Thanks.
 
couple things:

1.) your geared pretty deep with 8 tooth drivers and your 21/40, thats a 2.14 gear ratio with those drivers, which will keep your rpm up high alot of the time.

2.) whats the helix angle on the sec? are the clutchs warm,hot ???

3.) reeds in the yamahas are plastic stock, the carbon fiber petals are ok, likely just a bit stiffer and they help the throttle response slightly but shouldnt really hurt the mileage.

I would look at how warm the clutchs are, the gearing combo you have will make you need quite a bit of weight in the clutch to hang onto the belt, belt slip will eat up gas mpg in a hurry.
 
My primary weights are 8DN-17605-10 with Steel 17.2 rivets inside and out. 15.6mm rollers.
(I have a different set of weights for out west/at elevation, different gearing, and different track.)
It's about -26 right now and I don't have the garage heated so I'm not going to look right now, but I believe I have a 42/44 degree helix in the TSS-04 clutch. I've always had good belt life since I've had the sled, and I can't say I've had any clutch heat issues, but it is something I have never directly checked. I'll remember to pop the hood next time I'm out with it and feel the clutches next time I'm out with it. What would be a good target RPM for trail running at about 50 MPH? I was looking to pick up a 23T upper gear anyhow. I think you may be onto something with higher than normal RPM's. I'm also thinking I should look for a steeper helix for my secondary for sea level elevation. Any suggestions?
Thanks for the quick responses guys. I didn't think the reeds could contribute to such poor mileage all else being equal.
 
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I was able to pick up a used stock viper secondary this afternoon. I will try it out next chance I get. What would you Viper Guru's recommend for a primary setup. A local salvage yard was asking more than I am willing to pay for a used primary. I can buy weights, rollers, and a spring and have no problem changing them out. I also plan on going to a 23T top gear when I can source one. I would think 23/40 gearing with 8tooth drivers would be in the ballpark for a 144" ripsaw track. Do you think I'd be ok decreasing the roller diameter for more primary force, or should I do that in conjunction with different weights. As stated previously, I have the 8DN-10 primary weights.
Thanks again for all the help.
 
Hang on a second grizz, before you go buyin and changin a bunch of things. Dont want to sound like i am saying there is a need to swap out your parts,they were just observations that came into my head looking at your set up.

what kind of riding do you do with this sled, are you doing alot of climbing or using it as a flat land and hill playing sled?

gearing it up a little will certainly help as it will lower the rpm but give you more speed to roll along,agin this depends on what your doing with it, but since you only are using a 1.25 track instead of a 2 inch lug i assume its not steep and deep climbing,but i would rather ask then assume.
 
I would be setting it up for flat land trail/off trail riding. I have 19/42 gearing for when I go to the mountains. I use the factory recommended settings for the primary for 8,000-10,000 ft and for the secondary, I have the afore mentioned TSS-04 Secondary with a 42/44 helix and I believe it is a red spring. (Going from memory on the secondary.) I have a different skid I bolt in and run a 159"x2.125" track when set up for the mountains. I also follow the factory recommended settings for jetting at the same altitudes. This setup worked well last year, and I'm not so concerned with mileage in the mountains as I am in neck deep snow usually.
It is for local riding I'd like to improve my mileage. This is where I use the 144"x1.25" track, current 21/40 gearing which I plan on changing to 23/40, 8 tooth extroverts. Because my sled is a mountain viper, my primary came with the 8DN-10 weights and the 15.6mm rollers. I never got a stock secondary when I purchased the sled. The TSS-04 cam and spring I have is for a high altitude setup with triple pipes (which I have removed and replaced with stock exhaust.) That's why I bought a used secondary this afternoon. According to the manual, the stock mountain viper would have a 45degree helix with a green spring. What I purchased today should be for a stock short track viper. A 47 degree helix with a red spring. I know I could have looked for a new/used helix and spring for my TSS-04, but for roughly what I would have spent for those items, I opted to pick up a used stock secondary.
I don't have nearly the clutching experience that you or others here have. Looking for options on the primary (weight/roller combinations).
To answer your question directly, I am looking to set it up for flat land trail/boon docking type of use.
 
We are running the 8 tooth drivers, 22-38 gears. OEM primary clutch weights and springs. The secondary has the 51/43 helix. Our Viper runs great and milage is better than my SXR's Oh, the track is 136 11/4 with 156 studs. The off trail and on trail performance is much better with the 8 tooth drivers as well. I think we average around 12 mpg. Al
 
grizz, youll be right about the same gear ratio as Al is after you change the top gear, so that will help you out.
You can still use the 8dn10 weights if wanted, they are a decent weight profile. With the bigger rollers you should be able to use the 47 straight helix. Youll just need to be around 8500-8600rpm peak. You will get alot smoother upshift and super improved backshift by using your roller sec. All just depends on how much riding you do on and off the gas.

next time when you ride it, like you said, just stop and flip open the hood. If theres heat there youll know it with a simple touch test. You will instinctively pull your hand away from something too hot to touch, if you cant put your hands on it for more then 2-3 seconds before pulling away, its way too hot and you need to work on the clutch(belt slip). It should be just warm if its perfect.
 
Well, I got a chance to put about 80 miles on yesterday with a stock secondary and a 23 tooth top gear. I am now at 23/40 gearing with 8T extrovert drivers. Mostly playing in powder so not a real good place to check fuel mileage. I have 65 miles on the last full tank and I am down to 2 bars, but as I said a lot of powder busting. I did stop and feel my clutches. They were warm, but I could keep my bare hand on both of them indefinitely. Sled still seemed to pull real hard and I was happy with shifting and backshifting. I think I was peaking between 8600 and 8900 RPM. I know 8600 is good, is 8900 a little steep on a stock engine? Mind you, all I have is the factory tach so it's tough to get a definitive reading.
 
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