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Discussion Starter · #1 ·
Alright. I bought the performance series HMF pipe. I also bought the carbkit and air filter.

The carbkit came with 3 jets.

"# Basic Jet Kits Includes: Individual Keihin Round Jet: 138,142,145 "

I have no idea what to do with these jets. I gave them to my buddy who's installing them, and he said he has no idea what to do. He says he needs what altitudes their set for?

Can somebody please just tell me to tell him what to do? He rebuilds quads for a living. He knows what he's doing, but these jets confuse him.

Thanks.

Icedgreece.

*here are the jets I bought

http://hmfracing.com/shop/performance/jettingefi-kits/rancher-350-00-06-jets
 

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Those are main jets. He rebuilds quads and doesn't know what the jets are for? You need to remove the stock jet and see what is in there. Probably 2 sizes up...
 

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Discussion Starter · #3 ·
Those are main jets. He rebuilds quads and doesn't know what the jets are for? You need to remove the stock jet and see what is in there. Probably 2 sizes up...
Yes, I was surprised as well.

He said that the numbers were for certain elevations. I'm at 1,263 m (4,143 ft). The jets are set for 900ft?

I'm not sure what's going on.

Thanks.
 

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Wow, is your quad all stock before these upgrades? If so, the carb is set for see level. To ride at 5,000 ft you need to drop 5 sizes from stock on the main jet. That will get you in the area for elevation.(on a stock machine)
 

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Discussion Starter · #5 ·
Wow, is your quad all stock before these upgrades? If so, the carb is set for see level. To ride at 5,000 ft you need to drop 5 sizes from stock on the main jet. That will get you in the area for elevation.(on a stock machine)
I'm sorry I'm a PC guy. I don't know anything about small engines. I maintain them but I do not mess with them.

So, I'm sorry I still don't fully understand. How many feet would the 138 jet be? The 142? 145? So say, my jet is at 142 right now, Sea level, I would need to use the 138 for 4 000ft? Or if it was 150, drop the jet to a 145 and i'd be at my height?

Again I'm sorry. I just want to tell him the correct information. He asked what level the jets were set at, so.
 

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I think they go by 2 numbers at a time, not 1. So if stock was a 150 you would want a 140 for 5,000 feet. But yes you are correct. If nothing has ever been done to it performance wise it will be jetted for sea level.
 

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Discussion Starter · #7 ·
I think they go by 2 numbers at a time, not 1. So if stock was a 150 you would want a 140 for 5,000 feet. But yes you are correct. If nothing has ever been done to it performance wise it will be jetted for sea level.

What if it is adjusted? How will I know what elevation it's set for?
 

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Stock size for the 350 Rancher is as follows:

Under 5,000 feet = #130

Between 3,000-8,000 feet = #125

Keep in mind with the pipe and aftermarket air filter, you will have to go up on the jet sizes, as Red has stated.

 

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Discussion Starter · #9 ·
Stock size for the 350 Rancher is as follows:

Under 5,000 feet = #130

Between 3,000-8,000 feet = #125

Keep in mind with the pipe and aftermarket air filter, you will have to go up on the jet sizes, as Red has stated.


Thanks that picture helps a lot.

& up sizes? So the lower the number=bigger jet= higher altitude?
 

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So the lower the number=bigger jet= higher altitude?
No, lower number = smaller jet = high altitude.

The higher the altitude, the less air you'll have, so you need less fuel to keep the air/fuel ratio correct.
 

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Discussion Starter · #11 ·
So the lower the number=bigger jet= higher altitude?
No, lower number = smaller jet = high altitude.

The higher the altitude, the less air you'll have, so you need less fuel to keep the air/fuel ratio correct.
So, if the stock is 130, I Just bought 3 pointless jets as a waste of money? Since they are all higher numbers.
 

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So the lower the number=bigger jet= higher altitude?
No, lower number = smaller jet = high altitude.

The higher the altitude, the less air you'll have, so you need less fuel to keep the air/fuel ratio correct.
So, if the stock is 130, I Just bought 3 pointless jets as a waste of money? Since they are all higher numbers.
But with an aftermarket pipe and air filter you will need higher numbers, but I don't know which one you will need.
 

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Discussion Starter · #13 ·
No, lower number = smaller jet = high altitude.

The higher the altitude, the less air you'll have, so you need less fuel to keep the air/fuel ratio correct.
So, if the stock is 130, I Just bought 3 pointless jets as a waste of money? Since they are all higher numbers.
But with an aftermarket pipe and air filter you will need higher numbers, but I don't know which one you will need.
I live in the rockies, I need the higher altitudes. And I know. They said they were tested at 900ft so I don't know what that means.

Who knew getting a pipe would be so much work, eh?
 

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So, if the stock is 130, I Just bought 3 pointless jets as a waste of money? Since they are all higher numbers.
But with an aftermarket pipe and air filter you will need higher numbers, but I don't know which one you will need.
I live in the rockies, I need the higher altitudes. And I know. They said they were tested at 900ft so I don't know what that means.

Who knew getting a pipe would be so much work, eh?
i know what you mean i just put the hmf comp series and a k&n filter and now im fumbling with jets also oh and you should get a new pulg so you know if your running rich or not by checking the plug to see the color
 

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So, if the stock is 130, I Just bought 3 pointless jets as a waste of money? Since they are all higher numbers.
But with an aftermarket pipe and air filter you will need higher numbers, but I don't know which one you will need.
I live in the rockies, I need the higher altitudes. And I know. They said they were tested at 900ft so I don't know what that means.

Who knew getting a pipe would be so much work, eh?
Anytime you make any modification to the intake or exhaust system you must rejet.
 

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If they recommend the 142 near sea level, go down 2 sizes for your elevation. Try the 138 and go from there. You may also have to adjust your a/f screw.

This is what DynoJet does. They always split 0-3000ft, 3000-6000ft, and 6000+ft, with drops of 2 sizes for each range.

Rob
 

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Discussion Starter · #17 ·
If they recommend the 142 near sea level, go down 2 sizes for your elevation. Try the 138 and go from there. You may also have to adjust your a/f screw.

This is what DynoJet does. They always split 0-3000ft, 3000-6000ft, and 6000+ft, with drops of 2 sizes for each range.

Rob
Okay, thanks.

I will go to him tonight and keep updated.

**is there more than 1 jet in the carb I need to change?

Thanks for all the fast and great help guys, I know I'm pretty hard to work with.
 

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It is our pleasure to help you out... The main should be the only one you need to tinker with but yes there are more jets.
 

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The main should be the only one you need to tinker with but yes there are more jets.
i have to change my slow jet also because the engine is popping back through the carb
 
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