Hi
I was up in the Swedish mountains last weekend testing my newly Cpr piped viper with an 144 2" camo track.
The Sled has "for now" stock short track clutching and gearing but with 8 tooth anti ratchets. I have also installed (Opticool headgasked and a srx cooler.)
Revs: turning 8800rpm in pow and around 8900rpm on trails (short pulls) at the moment so i need to adress that later (see second question further down)
Milage: 5,77mpg in the pow.
Elevation around 1000 to 1500 feet, air temp -0F to -15F
..to the issue:
Jetting is as following:
Pilots: 47.5 across
Needle: pto 3,5 center 4, mag 4
Main: pto 160, center 160, mag 162.5
Vented to airbox
Forgot to check fuel screws... it feels like the sled is running rich, but can the fuel screws have that much impact? it really clears up after 6500rpms. Reason I ask is because I got the jetting advise from here a couple of months ago and i asked for jetting spec for 1000-3000ft and around +15F which should mean that this thing will be pig rich later in the season?
So can the fuels screws (wich i think is set to stock (was crisp with stock jetting and exhaust)) have that much impact? or do i have to change the needle position back to stock for easter riding when the air temp is around +15F to +40F?
Second question: followed "the advise" to get me some HC weights (40-10) , 15,6 rollers, green sec and a 50/40 helix but i cant find a "low elevation" setup for trails and backcountry riding for a cpr piped, longtracked viper with a 144 2" lug track, 8 tooths anti ratchets and otherwise stock gearing.
I hope you understand and thanks!
I was up in the Swedish mountains last weekend testing my newly Cpr piped viper with an 144 2" camo track.
The Sled has "for now" stock short track clutching and gearing but with 8 tooth anti ratchets. I have also installed (Opticool headgasked and a srx cooler.)
Revs: turning 8800rpm in pow and around 8900rpm on trails (short pulls) at the moment so i need to adress that later (see second question further down)
Milage: 5,77mpg in the pow.
Elevation around 1000 to 1500 feet, air temp -0F to -15F
..to the issue:
Jetting is as following:
Pilots: 47.5 across
Needle: pto 3,5 center 4, mag 4
Main: pto 160, center 160, mag 162.5
Vented to airbox
Forgot to check fuel screws... it feels like the sled is running rich, but can the fuel screws have that much impact? it really clears up after 6500rpms. Reason I ask is because I got the jetting advise from here a couple of months ago and i asked for jetting spec for 1000-3000ft and around +15F which should mean that this thing will be pig rich later in the season?
So can the fuels screws (wich i think is set to stock (was crisp with stock jetting and exhaust)) have that much impact? or do i have to change the needle position back to stock for easter riding when the air temp is around +15F to +40F?
Second question: followed "the advise" to get me some HC weights (40-10) , 15,6 rollers, green sec and a 50/40 helix but i cant find a "low elevation" setup for trails and backcountry riding for a cpr piped, longtracked viper with a 144 2" lug track, 8 tooths anti ratchets and otherwise stock gearing.
I hope you understand and thanks!
Last edited:
yamalars
Member
Fuelscrews only effects idle and just above idle. In your case i would carefully lean out the needles, set pto at 3,25 and center/mag at 3,5 and try it.
Use only premium gas if you could get it, and add octane booster if you only can get 95. About the HC setup you should find what you need with a search on here.
Use only premium gas if you could get it, and add octane booster if you only can get 95. About the HC setup you should find what you need with a search on here.
Thanks for the reply and info on the fuel screws yamalars! However is it safe to run the needles lower Than i've set them? I've read that it needs to be in "richmode" or im facing a burndown?
I've searched two weeks for a hc setup for low elevation, longtracked, big lugged, cpr/hauck piped vipers without any luck but i Will continue to look
Otherwise i can always test the trial and error way!
I've searched two weeks for a hc setup for low elevation, longtracked, big lugged, cpr/hauck piped vipers without any luck but i Will continue to look
Otherwise i can always test the trial and error way!
yamalars
Member
Rich yes, but not blubbery.. I would lean them down some and try it. maybe that needle setup you have is for a gutted airbox? Your's stock?
Hopefully someone with a simular setup will shim in here and enlight us..
Hopefully someone with a simular setup will shim in here and enlight us..
viperhauck
Member
I get a good hc setup from mrviper to a cpr piped viper mm last year. Dident remember it exactly but it was a 50/38 helix and the weight was loaded in heel and middle hole. Its my friends viper and that one runs good. Can check with my friend if you want but I yhink mrviper show up here soon and let you know
Yamalars: i Will try to lower the needle in the middle carb leaving the mag side as it is for now.. I've been doing airbox mods (gutting the box) on my previos sleds and as i remember it the sleds been running richer after i gutt the Box?
Viperhauck lets wait and see if he shows up, if he dousnt you're more than welcome to ask you're friend about the setup
Viperhauck lets wait and see if he shows up, if he dousnt you're more than welcome to ask you're friend about the setup
Viperhauck: well it seems like his not able to help me in this case (or missed this thread) well if you could get hold of the hc setup from your friend it would be great.
problem is your gonna burn it down if you lean it out too much, it needs to be rich to live. You can play with your needle settings as yamalars defined but you need to know what your doing. The center and mag are the 2 hottest cylinders from the increased compression, so those have to be richer then the pto does.
for clutching, helix is fine, green dot sec fine, you should have 4-5 grams in the heel and 4.3 grams in first hole, empty tip.
your not going to get good gas mpg, its a piped viper and with 8 tooth drivers and the stock 22/38 gearing your running a 1.94 ratio, along with a 2 inch lug 144 track, thats eats up gas mpg. The best youll see is maybe 9 mpg if you ride it on groomed trail, if all you ride is powder, well, it will be alot lower.
you wanna go fast it cost money and in this case its gas money!
for clutching, helix is fine, green dot sec fine, you should have 4-5 grams in the heel and 4.3 grams in first hole, empty tip.
your not going to get good gas mpg, its a piped viper and with 8 tooth drivers and the stock 22/38 gearing your running a 1.94 ratio, along with a 2 inch lug 144 track, thats eats up gas mpg. The best youll see is maybe 9 mpg if you ride it on groomed trail, if all you ride is powder, well, it will be alot lower.
you wanna go fast it cost money and in this case its gas money!
yamalars
Member
No, it will be leaner with a gutted box beqouse you'r letting more air in and leaning out the mixture. About midrange mixture, woulden't a srx carb rackYamalars: i Will try to lower the needle in the middle carb leaving the mag side as it is for now.. I've been doing airbox mods (gutting the box) on my previos sleds and as i remember it the sleds been running richer after i gutt the Box?
Viperhauck lets wait and see if he shows up, if he dousnt you're more than welcome to ask you're friend about the setup
(wich are a dime a dozen) work better with these pipes?
I mean they have richer needle/nozzles vs. viper so 3,25-3,5 needle setting would be safe (without blubber=)? What do you think Don?
srx rack would for certain be better they are indeed richer needles and nozzles in them then a viper rack. Not that you cant use the viper ones but the settings will be smaller on the srx rack as yamalars indicated.
Yamalars: Are you sure? cause i've been a member at HCS for several years where we discussed "gutting the airbox with vent lines mounted to the airbox" and the general conclusion was that if the carbs are vented to the airbox then the carbs "see/feel" the atmospheric pressure in the airbox.
And if the airflow is increased there is a stronger vacuum pull at the carbs which causes any given main jet to suck more fuel than it otherwise would have?
Gutting the airbox as we know increases airflow and as the vent lines are mounted to the box there would be an increasad vacumm signal.
Thats why a gutted airbox with carbs vented to it should cause the sled to run Richer!?
If you dont vent the carbs to the airbox a gutted airbox would indeed make it run leaner as the carbs dont realize the extra vacumm but only the extra airflow.
This might be wrong but as the sled is jetted for airbox vented carbs i do believe that gutting the airbox would make it even more blubbery.. However I will try to lean out the needles and then i might gutt the airbox ! Thanks for the advise regarding srx rack i will have that in mind if i dont get it to run crisp during this spring!
mrviper700: thank you for the needle advise I will try lean it out very carefully (pto 3,5 center 3,5 and mag 4.0 to begin with) and if im right about gutting the airbox i should be able to get it spot on!?
Regarding clutching glad to hear that i might have a working setup is there any advise regarding spring twist, 60,70 or 80?
About mpg i dont really care as i only run it for 200-300 miles a season.
yamalars
Member
Yes, you'r probobly right about the airbox if it's vented there, I'm used to vent to atmosphere.. and didn't remember
that your's vents to box, sorry
Hope you get it running right soon and if you want to try srx carb's you should contact "viperhauck"
on here, he will set you up at a very good price i think!
that your's vents to box, sorry
Hope you get it running right soon and if you want to try srx carb's you should contact "viperhauck"on here, he will set you up at a very good price i think!
Gutting the airbox decreases restriction and increases airflow. Lower restriction = lower vacuum in the airbox.
Lower vacuum in the airbox = lower vacuum applied to the float bowls (if they're vent into the airbox).
Lower vacuum at the float bowls = more fuel to flow through the main jet = a richer mixture. All else unchanged.
Lower vacuum in the airbox = lower vacuum applied to the float bowls (if they're vent into the airbox).
Lower vacuum at the float bowls = more fuel to flow through the main jet = a richer mixture. All else unchanged.
yamalars
Member
That make perfect sense! Very nice explained, thanks!
You're welcome. If you don't mind me asking yamalars, where is Edsbyn?
yamalars
Member
Sweden
Thanks for all the help I Will give you an update later in the season!
just picked up a boss highrise (so first project is to weld a frame for a "ski doo" type click on seat )and gytr mountain skis that hopefully will give this iron horse some flotation!
Special Thanks to yamalars, mrviper700 and viperhauck! Tack så mycket!
just picked up a boss highrise (so first project is to weld a frame for a "ski doo" type click on seat
)and gytr mountain skis that hopefully will give this iron horse some flotation!Special Thanks to yamalars, mrviper700 and viperhauck! Tack så mycket!
yamalars
Member
No problemo.. Good luck!Thanks for all the help I Will give you an update later in the season!
just picked up a boss highrise (so first project is to weld a frame for a "ski doo" type click on seat
Special Thanks to yamalars, mrviper700 and viperhauck! Tack så mycket!