As the new season approches many will need to clean thier carbs on thier srx,vipers. With the lousy gas and ethanol additive which attracts the moisture and gums up the small pilot jets, its almost mandatory now to do it. On this site theres pretty good threads on how to do this, so for the first timers these tools of information are here to be used in the tech sections.
One thing I would like to remind people of is geared more towards the viper owners. Vipers have lean needles and lean settings from the factory, tied together with more compression then a srx and lots more timing is a recipe for detonation and ultimately engine failure due to the very low quality gas we now have to use.
(now in this economy the
high gas prices will get more and more people to buy lower quality gas because of the cost factor,so this point of this thread will be even more important. 
)
Raising the needles in the vipers seems to shrug off alot of the on edge problems and the start of detonation in these sleds. Using the best possible grade of gas(premium) is the best insurance but not always possible due to ma and pa fuel stops out on the trail. By raising the needles some you richen up the most "used circuit" of the carbs while trail riding- the mid range circuit! Its here in the midrange, where you cruise old railroad beds 45mph ,groomed trails 50-60mph, etc.
This is also where most of the burn down problems will appear. By richening up this circuit it will reduce the heat and reduce chances of failure.
I know most people generally think that the vipers have some "weaker" crank but they use the same bearings and such as the popular srx700 does but the srx does not suffer the crank failure problems nearly the amount as the viper.
The viper uses LEANER carb parts,more ignition timing which places more heat into the piston crown and then coupled with a mono head of the viper AND slightly higher compression then the srx in the center and mag its just a sure recipe for problems with lousy fuel quality.
Raise the needle settings to richen up the mixture and reduce the temp of the piston crown. I also suggest using octane boost as added insurance. Octane booster is $6 a bottle here, I merely use a half bottle to a full tank fill up with the best possible gas I can get, so you get 2 full tanks of riding for a mere $6 insurance. 1 piston is $95, so you do the math...........
Theres guys who will say how much of a pain it is and such but what else can you haul in the trunk of these sleds?? how often do you fill up your sleds that a extra 30 seconds to add some booster required at a normal fuel stop is going to ruin your riding trip?
Raise the needles on the vipers and youll see far fewer problems over the winter. Since doing this practice of raising the needle settings I have yet to have one come back with a engine failure problem due to detonation on a stock machine or a machine driven by someone who spends alot of time cruising,or younger riders who are not as aggressive on the gas and more lower speed operation.
Just a tip to keep you up and running for the season, ride safe!!!
Clip position 4...two washers below clip.........................= 4
Clip position 4...washers split[one above one below clip] = 3.5
Clip position 4...two washers above clip ........................= 3 1/4
3.25 setting= is good for the average adult rider that does not ride a lot of railroad beds or groomed trails, and is on and off the gas.
3.5= is better for more slow riders or extended groomed trails riding where you have a lot of cruise time at 60mph.
You only need the 4th setting if you ride in extremely cold climates.
One thing I would like to remind people of is geared more towards the viper owners. Vipers have lean needles and lean settings from the factory, tied together with more compression then a srx and lots more timing is a recipe for detonation and ultimately engine failure due to the very low quality gas we now have to use.
(now in this economy the
high gas prices will get more and more people to buy lower quality gas because of the cost factor,so this point of this thread will be even more important. )Raising the needles in the vipers seems to shrug off alot of the on edge problems and the start of detonation in these sleds. Using the best possible grade of gas(premium) is the best insurance but not always possible due to ma and pa fuel stops out on the trail. By raising the needles some you richen up the most "used circuit" of the carbs while trail riding- the mid range circuit! Its here in the midrange, where you cruise old railroad beds 45mph ,groomed trails 50-60mph, etc.
This is also where most of the burn down problems will appear. By richening up this circuit it will reduce the heat and reduce chances of failure.
I know most people generally think that the vipers have some "weaker" crank but they use the same bearings and such as the popular srx700 does but the srx does not suffer the crank failure problems nearly the amount as the viper.
The viper uses LEANER carb parts,more ignition timing which places more heat into the piston crown and then coupled with a mono head of the viper AND slightly higher compression then the srx in the center and mag its just a sure recipe for problems with lousy fuel quality.
Raise the needle settings to richen up the mixture and reduce the temp of the piston crown. I also suggest using octane boost as added insurance. Octane booster is $6 a bottle here, I merely use a half bottle to a full tank fill up with the best possible gas I can get, so you get 2 full tanks of riding for a mere $6 insurance. 1 piston is $95, so you do the math...........
Theres guys who will say how much of a pain it is and such but what else can you haul in the trunk of these sleds?? how often do you fill up your sleds that a extra 30 seconds to add some booster required at a normal fuel stop is going to ruin your riding trip?
Raise the needles on the vipers and youll see far fewer problems over the winter. Since doing this practice of raising the needle settings I have yet to have one come back with a engine failure problem due to detonation on a stock machine or a machine driven by someone who spends alot of time cruising,or younger riders who are not as aggressive on the gas and more lower speed operation.
Just a tip to keep you up and running for the season, ride safe!!!
Clip position 4...two washers below clip.........................= 4
Clip position 4...washers split[one above one below clip] = 3.5
Clip position 4...two washers above clip ........................= 3 1/4
3.25 setting= is good for the average adult rider that does not ride a lot of railroad beds or groomed trails, and is on and off the gas.
3.5= is better for more slow riders or extended groomed trails riding where you have a lot of cruise time at 60mph.
You only need the 4th setting if you ride in extremely cold climates.
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this will also help explain why the needle is important and most overlooked
http://www.totallyamaha.net/forums/showthread.php?t=71011&highlight=viper+needle+settings
http://www.totallyamaha.net/forums/showthread.php?t=71011&highlight=viper+needle+settings
FJViper
New member
Great article Mr.Viper! This is going into the tech section right? This and your other write ups concerning the Viper need to be wrapped up in a 'welcome packet' for all Viper owners.
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If you do decide to bring along a can of octane booster, make sure to wrap it in something to keep it from rattling around and leaking. Oil, booster, barley pop, etc will make a mess if you don't stick it in a spare glove or other such cushion.
snomofo said:
great point, I do wrap mine in a spare peice of foam with rubberband on them, to keep from bouncing around in the trunk on our nice smooth trails.....
Suprx125
New member
Good write up! Thanks for the info!
Great info...How about a "How to Raise Needles" tech note for those of us new to this carb ?
I also enriched my pilots from a #45 to a #50 to minimize chance of kids burning up in the 30 mph zone they love to ride in.
One other thing....Why is it that Yamaha recommends decreasing main jet size for elevation gains and increasing the pilot jet size ? Just curious ! ( I have always up-jetted everything to help with cold starts )
Still have to open throttle slightly to start engine when warm. Not quite sure how to cure that ???
Thanks !!!
I also enriched my pilots from a #45 to a #50 to minimize chance of kids burning up in the 30 mph zone they love to ride in.
One other thing....Why is it that Yamaha recommends decreasing main jet size for elevation gains and increasing the pilot jet size ? Just curious ! ( I have always up-jetted everything to help with cold starts )
Still have to open throttle slightly to start engine when warm. Not quite sure how to cure that ???
Thanks !!!
Don't think the pilot circuit is really being used much at 30 mph.
jthemmer
Member
I have a holtzman, should I still raise the needles or just run it on the richer setting?
Chibravo said:
the reason they lean the main out and add pilot jet is you need fuel to accelarate a 2 stroke engine, rich down low and then tapering off to leaner on topend. The higher your up in altitude the less air there is and the mains will be smaller due to less air, the engine will move less air so you need less fuel.
as far as doing a raising the needle post, i can do that when i get a chance.
you just adding a bigger pilot will make the sled a tad richer but the needles is where the problem is and a 50 pilot wont make up for the lean needle settings. It will still burn down the center or mag cylinder on sustained mid range running like what kids do or slower riders. Its the combo of more compression, alot more ignition timing and the mono head with lean needles which make the heat in the piston and promote detonation which in turns eats the piston and usually the rod bearings on crankshaft.
so to make the viper run richer i have to raise the needle..what would you raise it to to be safe..4th groove and shim above an below or??
FJViper
New member
viper700t said:
I've got mine set at 4th groove, both shims over but here is an explanation.
Clip position 4...two washers below clip.........................= 4
Clip position 4...washers split[one above one below clip] = 3.5
Clip position 4...two washers above clip ........................= 3 1/4
Plenty of reading if you do a search on Viper needles.
so two washers above clip in the 4th groove is slighty richer than stock right?
Correct. Both my snakes have this done and I've not noticed any fuel related issues.
rx1jim
New member
Mr. Viper,
What brand octane booster do you reccommend? Thanks,
Jim
What brand octane booster do you reccommend? Thanks,
Jim
Can anyone give me a quick tutorial on adjusting the needles on my Viper ? I am doing an install of the SLP triple pipes and would like to move the needle clips. ( Procedure not found in Service manual )
Any help appreciated ! Thanks !
Any help appreciated ! Thanks !
