where is "stock" jetting jetted for?



18 replies to this topic
  • MiniMadMan50

Posted December 13, 2003 - 07:06 PM

#1

I was just wondering if anyone know what Yamaha is targetting geographically when the bike comes jetted "stock." I'd assume sea level? But the 165 main that comes stock in a WR426 seems like it might be a little lean for that? Cause I run a 168-170 up here at 2200 feet.

  • Eddie Sisneros

Posted December 13, 2003 - 07:11 PM

#2

where is "stock" jetting jetted for?



no where! :)

  • r1superstar

Posted December 14, 2003 - 09:51 AM

#3

I was just wondering if anyone know what Yamaha is targetting geographically when the bike comes jetted "stock." I'd assume sea level? But the 165 main that comes stock in a WR426 seems like it might be a little lean for that? Cause I run a 168-170 up here at 2200 feet.


Sea level....................Everything from a snowblower to a sportbike from Japan is jetted for sea level.

  • VB_Racing

Posted December 14, 2003 - 09:58 AM

#4

After having the jetting probs I have had with my last couple Yamaha's I would say they are jetted for " fantasyland level" :)

Dave

  • RichBaker

Posted December 14, 2003 - 10:10 AM

#5

They are jetted for the EPA testing lab :)
1st thing anyone that isn't riding in the Rockies needs to do is re-jet richer.....

  • tigerowner_ut

Posted December 14, 2003 - 10:27 AM

#6

They are jetted for the EPA testing lab :)
1st thing anyone that isn't riding in the Rockies needs to do is re-jet richer.....


It is lean in the Rockies as well. And obviously it doesn't work in the lab either as it is a red sticker bike in CA

  • r1superstar

Posted December 14, 2003 - 01:12 PM

#7

They are jetted for the EPA testing lab :)
1st thing anyone that isn't riding in the Rockies needs to do is re-jet richer.....


Richer? Hmmmm............Not really. In Hawaii they ran fine out of the box. (Both street and dirt.) Here in Utah, they load up like a SOB. Definately need to lean them out up here.

  • MiniMadMan50

Posted December 14, 2003 - 02:43 PM

#8

Sea level....................Everything from a snowblower to a sportbike from Japan is jetted for sea level.


I don't think so..
If they are jetted for sea level, why would I need to richen up my bike when I live at 2200 feet? :) Stock main for the 01 WR426 is a 165 (per my owners manual) everyone I know around here runs a 168-170 in theirs. And yes, it makes a HUGE difference.
Definetly sounds like fantasy land jetting to me..

  • Indy_WR450

Posted December 14, 2003 - 02:47 PM

#9

I think it is jetted for 10,000 feet as stock jetting is lean everywhere else. :)

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  • r1superstar

Posted December 14, 2003 - 06:06 PM

#10


Sea level....................Everything from a snowblower to a sportbike from Japan is jetted for sea level.


I don't think so..
If they are jetted for sea level, why would I need to richen up my bike when I live at 2200 feet? :) Stock main for the 01 WR426 is a 165 (per my owners manual) everyone I know around here runs a 168-170 in theirs. And yes, it makes a HUGE difference.
Definetly sounds like fantasy land jetting to me..


Are you running a stock exhaust system?

Anyways, all generators, snowblowers, streetbikes, dirtbikes, atvs from Japan are jetted for sea level. It has to be done to meet strict EPA regulations. If you don't believe me, ask your local dealer (a worthy one). Every unit we send through our shop has to be jetted for elevation.

From sea-level to about 3,000 feet elevation, atmospheric pressure decreases about one-inch-per-thousand feet of altitude-therefore our 29.92 barometer reading at sea-level now becomes about 27. At 5,000 feet, about 25, and 20.6 at 10,000 feet. Our engine (and carburetor) only react to air velocity-not weight of air. Not knowing this, the carburetor continues flowing the same amount (by weight) of fuel, and all of a sudden our "ideal mixture" at sea-level becomes extremely rich at higher elevations.

We are at 4260 ft. above sea level where I live, and people who live higher get leaner jetting. Not to mention the power loss because of elevation. It's something like 4% per 1000 ft. above sea level.

So you are at 2200 ft. then you ar at about 90% of max power. I am about 85% of max power.


OOOH!! One more to help you out here. Higher elevations have less air density then lower ones. At high elevations our engines are getting less air, so they need less fuel to maintain the proper air/fuel ratio. Generally you would go down one main jet size for every 1750 to 2000 feet of elevation you go up (info for Mikuni carbs). If you normally run a 160 main jet at sea level you would drop down to a 140 at 4000 feet. Something else goes down as you go up in elevation is horsepower.


Care to debate anymore???

:D

  • Hick

Posted December 14, 2003 - 06:25 PM

#11

I was just wondering if anyone know what Yamaha is targetting geographically when the bike comes jetted "stock." I'd assume sea level?


Here's your answer:

It is jetted to run well at sea level with the airbox lid and exhaust insert.

There, I said it.

:)

  • Eddie Sisneros

Posted December 14, 2003 - 07:34 PM

#12

yep,the stock jetting is for the corked up wr.un cork it and the jetting goes out the window.look at yz jetting if want the real sea level uncorked jetting.still needs work,but useable.

  • RichBaker

Posted December 15, 2003 - 03:31 PM

#13

OOOH!! One more to help you out here. Higher elevations have less air density then lower ones. At high elevations our engines are getting less air, so they need less fuel to maintain the proper air/fuel ratio. Generally you would go down one main jet size for every 1750 to 2000 feet of elevation you go up (info for Mikuni carbs). If you normally run a 160 main jet at sea level you would drop down to a 140 at 4000 feet. Something else goes down as you go up in elevation is horsepower.


Care to debate anymore???

:)


It's this kind of crappy, ARROGANT, know-more-than-you-do attitude that pisses people off, and drives them AWAY from your shop :D

Yes, the WR is jetted for sea-level as delivered by Yamaha to the dealers door, once all the corks are removed, and possibly add an aftermarket exhaust everything changes.....and if the dealer is removing the corks, it should have been re-jetted accordingly, before it was delivered to the buyer!

  • r1superstar

Posted December 15, 2003 - 06:33 PM

#14


OOOH!! One more to help you out here. Higher elevations have less air density then lower ones. At high elevations our engines are getting less air, so they need less fuel to maintain the proper air/fuel ratio. Generally you would go down one main jet size for every 1750 to 2000 feet of elevation you go up (info for Mikuni carbs). If you normally run a 160 main jet at sea level you would drop down to a 140 at 4000 feet. Something else goes down as you go up in elevation is horsepower.


Care to debate anymore???

:D


It's this kind of crappy, ARROGANT, know-more-than-you-do attitude that pisses people off, and drives them AWAY from your shop :D



Do I really care? I'm in sales...

And I speak the truth. Geez lighten up dude!! :) Or go crawl back under that rock you slithered out from.

Oh, you have just been rewarded a friendly PM from me. :D

  • James_Dean

Posted December 15, 2003 - 10:19 PM

#15

dirtbikes, atvs from Japan are jetted for sea level. It has to be done to meet strict EPA regulations.



Closed course competition vehicles don't meet EPA regulations. The comment does not apply to Yamaha WR's... does it? :)

WR's are lean at idle and transition thru moderately good to lean jetting looking across the throttle range. The jetting can't be evenly adjusted with the stock needle from low to high altitude without getting compromises at 1/8-1/4 and 3/4 throttle positions. Adjust the fuel screw, swap pilots, clip positions, and main jets, and there are still tradeoffs.

The reality is that Yamaha WR jetting is a series of compromises for running anywhere from a corked-up-throttle-limited setting that doesn't need a main jet, to a full throttle & completely opened up exhaust and from sea level to about 6000ft with reduced emissions. Essentially the places most people ride with a few likely exhaust configurations using something halfway reliable.

The settings may seem stupid, but there were surely a long list of requirements the Yamaha technicians were trying to meet with a basic factory specification. If you uncork the bike, at the very least, start over with the YZ parts and take it from there.

OOOH!! One more to help you out here... (info for Mikuni carbs). If you normally run a 160 main jet at sea level you would drop down to a 140 at 4000 feet.



Note- There is not a bike in the Yamaha WR400-450 forum category with a Mikuni carb. The Keihin carbs use main jets in the range of 155-175. Keihin jets are numbered based on diameter, while Mikuni are based on flow rates.

Nearly everyone here knows to lower their jetting with altitude. The condescending comments aren't helpful.

James

  • r1superstar

Posted December 16, 2003 - 07:10 AM

#16

Closed course competition vehicles don't meet EPA regulations. The comment does not apply to Yamaha WR's... does it? :)



My error about the EPA and the closed circuit units James. You are correct here, but they are still jetted for sea level.

WR's are lean at idle and transition thru moderately good to lean jetting looking across the throttle range. The jetting can't be evenly adjusted with the stock needle from low to high altitude without getting compromises at 1/8-1/4 and 3/4 throttle positions. Adjust the fuel screw, swap pilots, clip positions, and main jets, and there are still tradeoffs.

The reality is that Yamaha WR jetting is a series of compromises for running anywhere from a corked-up-throttle-limited setting that doesn't need a main jet, to a full throttle & completely opened up exhaust and from sea level to about 6000ft with reduced emissions. Essentially the places most people ride with a few likely exhaust configurations using something halfway reliable.

The settings may seem stupid, but there were surely a long list of requirements the Yamaha technicians were trying to meet with a basic factory specification. If you uncork the bike, at the very least, start over with the YZ parts and take it from there.

Note- There is not a bike in the Yamaha WR400-450 forum category with a Mikuni carb. The Keihin carbs use main jets in the range of 155-175. Keihin jets are numbered based on diameter, while Mikuni are based on flow rates.[/qoute]

The priciple remains the same. That was just an example.


Nearly everyone here knows to lower their jetting with altitude. The condescending comments aren't helpful.

James


Thanks for your input James,
However condescending comments come after condescending comments (not yours). My comments were made in a way that others comments were received. No harm intented. I am just a very high strung individual. It's my personality and it takes a while to get used to it. I'm actually a pretty cool and unique individual.
:D

  • James_Dean

Posted December 16, 2003 - 08:26 AM

#17

I believe you're right about the bikes being jetted (mostly) for sea level, with restrictions in-place.
No harm done, and your perspectives are appreciated.

Thanks,
James

  • r1superstar

Posted December 16, 2003 - 02:43 PM

#18

I believe you're right about the bikes being jetted (mostly) for sea level, with restrictions in-place.
No harm done, and your perspectives are appreciated.

Thanks,
James




Hey James, thanks man. Same to you. :)

  • renegade

Posted December 17, 2003 - 03:47 PM

#19

All bikes are jetted to run properly in Hoboken, New Jersey, and no where else. :D That might explain why no ones jetting, including my own, seems right! :)




 
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