Where are the factory jetting/clutching charts?

supercharged111

supercharged111

Member
Joined
Sep 12, 2011
Messages
123
Age
42
Location
Da U.P.
I've searched the tech section and beaten the forum's search tool to death and the best I've found are a few isolated references. I've been reading and re-reading the how-to's in the tech section to make sure I fully grasp the concepts so I can deviate from factory to find a more ideal setting, but I do need a solid, safe baseline from which to start. For that, I look to Yamaha. I'm told my target altutude is 7,000-10,000ft, but I'm trying to do a little research to see if I can narrow it down a little more from there based on the specific trails I hit. Does anyone have the full factory jetting and clutching charts that break it down by temperature and altitude?
 
i dont think the high altitude adjustments are in the tech section, only the baseline. someone correct me if i am wrong.

however, i have the altitude adjustments by yamaha for most 2 strokes, just need your sleds info: model, year, and cc's.
 
I've got a '98 VMax 700SX. If you could, can you share the specs for 6,000-10,000 feet? I actually live at 6,000 feet, but only received 4" of snow last year at my house. It'll give me an idea of where to extrapolate if I venture outside the 6000-10000.
 
bluemonster1 said:
check your manual,should be a section there that shows jetting and elevations.....and temps of course
Click to expand...

I would if I had one.

Mysledblows said:
I had a pretty solid set up for my 98 for 8000+. If interested I can check my notes.
Click to expand...

Did you have the single exhaust? Search engine turned up a million hits for jetting q's on piped sleds.
 
Single pipe. Wife rode it that way for years and then a couple years ago we went to a ported/piped set up in it. I'll dig my notes out tonight and let you know what we ran. It worked well at the time.
 
nice work dmace!

i found the tech manual to be slightly different on some of the carb setups.

for 5000-6600' carb as follows for 0 degrees:
main jet: #1-137.5
#2,#3136.3
pilot jet: #55
needle in #2
fuel screw 1 5/8

for the clutch:
8CH-00 weights w/ 10.3 alum in the outer hole 13.9 inner
pink/pink/pink spring
14.5mm rollers
red secondary spring @60(3-3)
45 degree helix
 
Sweet, thanks a ton guys. Am I to assume the starting position for the idle mixture screw remains at 1.5 turns as the elevation and pilot jets change? It's reassuring to know that I can hit the trail and not wonder right off the bat if the machine is gonna chug or melt down.
 
Correct, you still want to "start" at 1-1/2 turns OUT from lightly seated and then adjust from there. Here is the page from the manual that shows how to adjust the screw for each carb. You basically start with each screw 1-1/2 turns out then adjust one at a time until the engine is at the point of highest idle, then turn the idle screw down to normal (1500-1700) and start over with the next screw.
 
Ahh, just like the idle screws on a car's carb then. Since I'll be on the fringe of 60s or 62.5s, I think I'll buy both and experiment. The size of the pilot, once the idle screw is properly set, gives you the off idle snap if I understand it correctly. I'm glad I got my hands dirty last year fully tuning my Edelbrock carb so I could get a feel for the transitions between different circuits though admittedly I cheated and used a wideband.
 
Last edited:
A wideband is certainly the way to go for fine tuning but for these small two stroke motors, reading the plugs is all you need. The pilot jet will determine your off-idle acceleration but be careful not to go too big or you'll load up and bog every time you snap the throttle.

Also, careful with setting the fuel mixture screw at low elevation and then taking it 6,000 ft up. When you find the best setting, go IN about 1/4 turn so your not too rich at higher elevation.
 
You must log in or register to reply here.


Back
Top