Help a noob get a ballpark jet for a toomey at altitude?

[ereksonj]

I want to get a toomey pipe but I don't want to buy a bunch of jets that I don't need. Can someone give me a ballpark range of jets I should grab so I don't have to buy jets as I experiment and as conditions change?

I'm running 32:1 between 4,000 and 10,000 feet of altitude (sometimes in just one ride). I also like to ride in temperatures from 0 to 110 Fahrenheit (I live in northern Utah). My airbox cover is modified to let it breath much better and the oil injector has been deleted... Other than that, I think it's stock... Thanks in advance.

 

[89blaster89]

your gonna have to switch jets if your going from 0-100 Fahrenheit and 4000-10000 altitude, otherwise your engine will be done, im gonna say you will need jets from 270-310. there 3 bucks a jet witch is nothing

 

[ereksonj]

your gonna have to switch jets if your going from 0-100 Fahrenheit and 4000-10000 altitude, otherwise your engine will be done, im gonna say you will need jets from 270-310. there 3 bucks a jet witch is nothing

Thanks. I know I'll need to use different jets depending on conditions, just needed to know where it should be around the included 310 jet (bigger, smaller, by how much). I appreciate the quick response. I'll be sure to get more on the leaner side then...

 

[ereksonj]

What do you think about using one of these air density guages to help with jetting?

 

[Awk08]

you're asking alot to suggest main jets for the wide ranging elev./temp ranges you say you may encounter.
there is no magic # jet for what you describe,
get ready to rejet constantly, and buy 270 - 330 mains

the higher the temps and altitude, the less fuel you'll need as the air is thinner
if you jet perfectly at 70 degrees, you'll be rich at 100, and very lean at anything under 50.
you'll need to up your main as temps drop.
if you experience 30-40 degree drops in one day, jet rich or fry your chit !

i run a toomey on my black bike, 32:1, open airbox, stock carb/reeds, head mod, 1800-2400' elevation.
it likes a 300 main jet in the summer temps 60-80+
i throw a 330 in it for winter temps 50's - 30's
it's rich mid day in the 50's, but i'm safe to ride into the night down into the 30's
i also adjust the airscrew daily according to temps.

for the elevations you describe, i'd say 300/290/270
for temps below 40/50 and down to zero, i wouldn't hesitate to try 310/320/330 jets.

you'll need to do plug chops at different temps, write down your findings and remember to rejet for each temp swing, daily if needed.
the climb in elevation will only make it richer = safe,
as long as you're not fouling plugs, take extras with you

 

[Awk08]

What do you think about using one of these air density guages to help with jetting?

that appears to need some kind of sensor/sending unit and possibly 12 volts to operate

 

[ereksonj]

Wow, lots of useful information, thanks!

the climb in elevation will only make it richer = safe,
as long as you're not fouling plugs, take extras with you

I've done the 4,000-10,000 foot climb a few times now with no problems other than idling issues at the peak. (It's about a half hour ride). I think as I climb in elevation, the temperature drop reduces the amount of richening I experience, though.

However from what I've heard, a modded engine is more sensitive to jetting changes than a stock one. Do you guys think that is the case?

 

[Awk08]

Wow, lots of useful information, thanks!



I've done the 4,000-10,000 foot climb a few times now with no problems other than idling issues at the peak. (It's about a half hour ride). I think as I climb in elevation, the temperature drop reduces the amount of richening I experience, though.

However from what I've heard, a modded engine is more sensitive to jetting changes than a stock one. Do you guys think that is the case?

yes thats possible the temp drop compensates for the elevation climb

and i do believe modded engines are way more sensitive to jetting than stock < especially with the oil injection still in use
i rode my '96 completely stock blaster from new till i sold it 8 years later, in all types or temp changes, and never even new about jetting changes, sold it with the stock 230(?) in it, still starting 1-2 kicks and running like a champ

 

[Larry's Shee]

Sounds like you'll become an expert in jetting, plug "reading", and changing them.

Mikuni pocket tuner shows 1 jet size for every 20 degrees change.
As to elevation I have no useful experrience other than a bike jetted for Mich would hardly run in the mountains near Sheridan, Wy.

There is a sticky on how elevation affects jetting, don't know if includes compensation info.

Might consider looking into a Dial-A-Jet. I know sled guys use them especially in the mountains.

And yes, the higher the performance level, the more you have to chase jetting. No idea how "finicky" a performance 4poke is.

Gee, I guess your situation is where a 4poke like a Warrior or 400ex might be an advantage.8-|

 

[Blaaster]

I want to get a toomey pipe but I don't want to buy a bunch of jets that I don't need. Can someone give me a ballpark range of jets I should grab so I don't have to buy jets as I experiment and as conditions change?

I'm running 32:1 between 4,000 and 10,000 feet of altitude (sometimes in just one ride). I also like to ride in temperatures from 0 to 110 Fahrenheit (I live in northern Utah). My airbox cover is modified to let it breath much better and the oil injector has been deleted... Other than that, I think it's stock... Thanks in advance.

I know not much about mountain riding, but I would ascertain that a lot of your riding would not be a WOT.

Therefore the main jet settings would not be as critical.

Riding on the needle is not quite as finiky as jetting for WOT.

For mountain riding, I would question that a Toomey could not be the correct choice of pipe as it is designed for top end performance.

Would a low/mid pipe be a better choice?

I may be barking up the wrong tree and someone who is experienced in mountain riding may prove me entirely incorrect.

 

[ereksonj]

I know not much about mountain riding, but I would ascertain that a lot of your riding would not be a WOT.

Therefore the main jet settings would not be as critical.

Riding on the needle is not quite as finiky as jetting for WOT.

For mountain riding, I would question that a Toomey could not be the correct choice of pipe as it is designed for top end performance.

Would a low/mid pipe be a better choice?

I may be barking up the wrong tree and someone who is experienced in mountain riding may prove me entirely incorrect.

Yeah, I've kind of been on the fence with the type of pipe I should get...

Although I will do a lot of mountain riding, I also like to play in the sand. I feel like I'm hurting for power a lot more when I'm in the dunes than when I'm in the mountains. And I think if I get into some tight spots in the mountains I will just have to work the clutch a little more, but I don't mind.

On the other hand, I share the quad with my girlfriend who is not as good with the clutch and shifting (she's only ridden once, but seemed to pick it up really well). I've hesitated on the toomey for her sake... I also like to give her rides sometimes, too and I think I could use the extra power for times when I do. She doesn't need a whole lot of power because she is so light (110 lbs with gear on).

What other pipes do you think I should consider? I think I read somewhere that the shearer has a pretty smooth power delivery. It seems like right bends are more top end, and I can't seem to find any of those anyways. eventually I would like to get it ported and maybe some other work down the road.

The DG pipe I have right now (came with it) isn't really pipey and has plenty of torque for my needs. I just want more power so I can make some of the steeper hills (again, I only really feel limited in the sand).

One more thing, I just put a 42 tooth on the rear... haven't had the chance to try it yet. (was struggling to hit the power band in 6th @ 60mph on mud flats)

 

[Blaaster]

I am an avid believer that for low/mid power one cannot beat the DMC Alien, the FMF Fatty coming a close second.

Maybe this will help with choice of sprockets.

Gearing Calculator

I am not trying to be smart but the DG pipe you have is only a little better than stock and most certainly holding you back, with the DG you will struggle to get 60mph with 22" balloons.

 

[ereksonj]

I think I want to go with the fatty now. I just feel like it will keep my RPM's lower and prolong my engine life... And I think my girlfriend will have an easier time with a lower power band.

So what sort of jets range should I buy for the fatty? Leaner than the Toomey?

 

[ereksonj]

Might consider looking into a Dial-A-Jet. I know sled guys use them especially in the mountains.might be an advantage.8-|

Sorry for the double post, but...

What exactly is a Dial-A-Jet supposed to do? How does it work? I've done as much research on them as I can and it looks like it just takes fuel from the float bowl and routes it up to the air intake of the carburetor, correct? Do I have to drill a hole in the carburetor to install it?

 

[Awk08]

I think I want to go with the fatty now. I just feel like it will keep my RPM's lower and prolong my engine life... And I think my girlfriend will have an easier time with a lower power band.

So what sort of jets range should I buy for the fatty? Leaner than the Toomey?

i don't know about the FMF keeping rpm's down, it comes on earlier which effectively will do just the opposite....get you in the powerband earlier = more rpms.
a higher "hitting" pipe (toomey/right bends) will give you more low rpm range under the powerband = less overall rpm's ?
does that make any sense to anyone else ?


my buddies all stock bike w/ FMF fatty/silencer runs a 290 @ our 1800' elevation.
i'd buy 280/270/260 mains @ your 4000'+ elevation
start large and plug chop each to confirm.

 

[Awk08]

Sorry for the double post, but...

What exactly is a Dial-A-Jet supposed to do? How does it work? I've done as much research on them as I can and it looks like it just takes fuel from the float bowl and routes it up to the air intake of the carburetor, correct? Do I have to drill a hole in the carburetor to install it?

from what i gather, the dail-a-jets work off of engine harmonics ?
it only works when it "hears" the engine begging for more fuel.
and yes, you must drill a hole in the back throat to mount them behind the carb slide

 

[ereksonj]

i don't know about the FMF keeping rpm's down, it comes on earlier which effectively will do just the opposite....get you in the powerband earlier = more rpms.
a higher "hitting" pipe (toomey/right bends) will give you more low rpm range under the powerband = less overall rpm's ?
does that make any sense to anyone else ?

If I understand your train of thought, You are saying that by hitting the power band sooner it will constantly want to climb out of the lower RPM's, right? And that if I get a Toomey pipe, the lack of power in the low end will allow me to lug it around without accelerating? I guess that makes sense. Hadn't thought of it that way...

I just figured that any time I needed to get on the pipe, I would be WOT under a heavy load. With this in mind, I figured the Fatty pipe would die off quicker than the Toomey, resulting in a lower RPM up the same hill. I like to do some pretty long hill climbs every once in a while and it makes me cringe to run my engine at 8500+ RPM's for more than a few seconds.