Looking to improve fuel mileage on viper for next season

drew24

drew24

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Joined
Mar 16, 2013
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955
Age
45
Location
NW Indiana
My viper got terrible fuel mileage this year. 9-9.5 mpg. I am thinking warm temps didn't help but even then my srx got 12 on the same rides and I am on the gas way more than my wife on the viper. I did have a problem with the clutches and changed springs and that solved that which I do think helped fuel mileage but with the one day we got to ride after that it still took quite a bit more fuel than the srx. I raised the needles to 3.5 and it is definitely rich. I did get to hear how my wife rides it through our radios and I think she would be fine at 3.25 but was wanting to do plug and piston wash check when it was actually cold out but never got to ride in cold temps. I don't think that is hurting the mileage too much. I am wondering if the m10 is the issue. If the m10 scrubs mph it almost has to hurt fuel mileage. Was thinking on trying to find a 8" wheel kit for the back but I see with the 121" you have to leave the inner rear wheels where they are and just move the outside wheels. Need some opinions on this. Thanks
 
Relatively in expensive items: more bogie wheels, single runner carbides, saddle-less skis, stock .91 inch track.
The easier it is for the sled to roll, less drag, the less load put on the engine, less fuel used. Some people may say run a 1.25 lug track so you aren't spinning as much but I say lighten the sled up as much as possible.

Try loosening your secondary a couple adjustments. This will allow the secondary to shift up sooner than the stock setting putting you into a higher gear ultimately leading to slightly higher speeds using less throttle (less fuel burned).


PS: please don't shoot me as I'm a chiropractor, my expertise is in spines. I only tinker with sleds as a hobby.
 
That's what I am thinking it is shaggy. I went through and replaced or cleaned and repacked every bearing on the sled. It rolls nice. It has stock track with stock gearing. I went through everything on this sled before season so I know everything else is perfect. I gotta think its the m10 because I know it should get better mileage than it was. Not sure if the 8" rear wheels would help or not. Don't want to put any more money it the suspension if its not going to get better. If I cant get it better I will get rid of it and put a mono in. I am very picky about the places I get gas so bad mileage is not good.
 
The bigger rear wheels would probably help some, will cut down on the rolling resistance. The mono is a good upgrade and shouldn't hurt fuel mileage.
 
The biggest problem I have is I have to much money in the m10. Will never get even close to what I have in it. I have the mono in my srx and I thought it did pretty good and we went through some pretty rough trails. Might look for a wheel kit with the offset axle and try it if it isn't to pricey to purchase. I was just thinking it did seem to have a lot of weight on the skis. Wonder if I adjusted that too if it would help. Maybe I need to pull the limiter in a notch.
 
The needles at 3.5 killed my mpg also on wife's sled. Moved back to 3.25 and it help quite a bit. Was surprised how much extra fuel she used when at 3.5.
 
super1c said:
The needles at 3.5 killed my mpg also on wife's sled. Moved back to 3.25 and it help quite a bit. Was surprised how much extra fuel she used when at 3.5.
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Maybe that's half the problem then. It was definitely reading quite rich on the plugs and the pistons. I will move them to 3.25 for next winter. She actually does pretty good about getting on the throttle so I think it will be fine. I wasn't sure how she would do coming off a 440 but she says she feels way more comfortable with the way the viper handles over the Arctic Cat 440 she was on before.
 
Track tension on m10 might be an issue. They do not use the same tension as the pro action. If you set it to pro action specs, it will be very tight when on the ground and tight up from there if you hit a bump. When they are unloaded, they are not tight.

what carbides and skis do you have?

also, assuming this is a stock viper with the bent tube hooked up?

center to center correct on clutches?

power valves working, installed and adjusted correctly?

I have not found m10 to remove fuel mileage by anything noticable, but will knock a few mph off top end. Big wheels will get most of that back. I think the fuel mileage drain is mostly from driving faster on all conditions compared to before and not realizing it. Not that this is your issue here. You have a huge problem.
 
BETHEVIPER said:
Track tension on m10 might be an issue. They do not use the same tension as the pro action. If you set it to pro action specs, it will be very tight when on the ground and tight up from there if you hit a bump. When they are unloaded, they are not tight.

what carbides and skis do you have?

also, assuming this is a stock viper with the bent tube hooked up?

center to center correct on clutches?

power valves working, installed and adjusted correctly?

I have not found m10 to remove fuel mileage by anything noticable, but will knock a few mph off top end. Big wheels will get most of that back. I think the fuel mileage drain is mostly from driving faster on all conditions compared to before and not realizing it. Not that this is your issue here. You have a huge problem.
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Track tension is set pretty loose. I have about 2" free hang sag. It has stock skis with triple point carbides and is shimmed. Vent tube is hooked up. Center to center is perfect along with belt deflection and clutch alignment. Power valves are cleaned and adjusted. If you haven't noticed much mpg loss with the m10 I am going to assume that is not my problem. Not worried about top end loss since this is my wifes sled anyway. Limiter strap is set as long as possible. Should I give a little more preload in the front shock to take some weight off the skis? I don't think I want to but not sure if it would help.
 
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weight on skis isn't going to be it. I know this is dumb but two things, are the power valves in upside down?

also, you can have the track too loose, it will run on the gaurds and drag. Correct track tension is to loosen till track jumps, then tighten one turn. Then do wot runs for speed, tighten track till speed drops, then loosen one turn. This will get you optimal tension.

Lastly, I have sold a couple cdi boxes to people with the same complaint. One just didn't run very good, the other had bad gas mileage and not great power, he found the box was not advancing the timing, it stayed flat. do you have a donner sled you can borrow one from to try?
 
Definitely not a dumb question but power valves are installed properly. I learned that the hard way on the srx. lol I read a thread somewhere a while back where you told about that way of setting track tension so I will do that next season for sure. I spent what little time I had on the snow riding so didn't get to do much testing. I didn't feel it rubbing but that doesn't mean much. The motor seems to have good power but there was a guy around my area on facebook selling a cdi for cheap. I almost picked it up just to have an extra. I might see if he still has it. On a side note I just remembered there was one time when my wife said she smelled gas but I never smelled gas when I rode it so I didn't think much of it. I will have to check needle and seats and the float level. Maybe it is dumping gas. Now that I know it shouldn't be the skid itself I'm not so worried. Now I know I will be able to get it better. I will go through the things I can and next winter get the track tension dialed in and hopefully that will do it. Thanks a bunch for the input guys.

Also on the track tension I originally set it at 1 1/2" of free hang and it loosened up to 2" after 600 bumpy miles so I was thinking I had it too tight to start with but I will dial it in next season the way you said and see where it is.
 
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i have a 04 viper s. It has quite a few mods to it, however i had poor mileage as well. I dropped the needles one position and fuel mileage went up. I also uesd to get a funny fuel smell from time to time. This cured it. Hope this helps.
 
Hey Drew, can you give us an update on your fuel mileage this year? You mentioned several things you were going to look at this off-season.

I just caught this thread looking for some mpg improvements on my 2001 SXR600 with an M-10. It seems I've heard a few people say the M-10 reduces fuel economy, but it's all speculation as far as I can tell.

Learned in another thread about the seats on the float needles, that's one thing I'm going to replace this off-season.

Let us know what you learned (if anything) :)
 
EotS1 said:
Hey Drew, can you give us an update on your fuel mileage this year? You mentioned several things you were going to look at this off-season.

I just caught this thread looking for some mpg improvements on my 2001 SXR600 with an M-10. It seems I've heard a few people say the M-10 reduces fuel economy, but it's all speculation as far as I can tell.

Learned in another thread about the seats on the float needles, that's one thing I'm going to replace this off-season.

Let us know what you learned (if anything) :)
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We haven't had a chance to ride the sled much yet. I did move the needles to 3.25 so we will see if it helps. Going on a trip next weekend so as long as there is snow I will see if its better or not.
 
Friend of mine had a chipped reed valve that was the culprit of his bad fuel mileage

Sent from my SGH-I337M using Tapatalk
 
Lowering the needles from 3.5 to 3.25 helped quite a bit. It still wasn't as good as the srx but wasn't that far behind either. Might have used 3-4 gallons more than the srx in 350 miles.
 
Different weights ,springs, helix ,, to roll on 3000- max at 8500..............look at sx 700 spec to get ideas.................... 90 mph all day with two grown up on sled....,.,90mph ,13-14 miles to gal...................
 
Whammy said:
Different weights ,springs, helix ,, to roll on 3000- max at 8500..............look at sx 700 spec to get ideas.................... 90 mph all day with two grown up on sled....,.,90mph ,13-14 miles to gal...................
Click to expand...

I might play with the clutching a bit next year if we ever get enough snow to tune it. It was getting about 11 mpg.
 
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