Mammoth jetting help

adub274
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adub274
Edited Date/Time 6/1/2014 8:31pm
Going from Las Vegas 2200' feet at 100 degrees to 8000' 75 degrees . 2 stroke class . Going leaner for sure but how much ? Pilot , needle , and main ? Some ballpark help would be great .
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DTHA70
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DTHA70 5/29/2014 6:09am
5/29/2014 6:09am
adub274 wrote:
Going from Las Vegas 2200' feet at 100 degrees to 8000' 75 degrees . 2 stroke class . Going leaner for sure but how much...
Going from Las Vegas 2200' feet at 100 degrees to 8000' 75 degrees . 2 stroke class . Going leaner for sure but how much ? Pilot , needle , and main ? Some ballpark help would be great .
get a couple cans of MRX02 for the weekend, you will hardly have to make any changes. that fuel was designed for two strokes at mammoth to take the guess work out.

100% worth the money.
FGR01
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FGR01 5/29/2014 8:16am
5/29/2014 8:16am
$167.76 for a 5 gallon can. Mother of god.
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GimpIndustries 5/29/2014 8:20am
5/29/2014 8:20am
Renegade's SX2 fuel is better than the VP stuff in my book.

adub274, I am going through the same questioning right now for my ktm 250sx for mammoth. I plan to work with JD Jetting and get a good baseline. Than spend some time dialing it in on the practice day.
crashnburn11 5/29/2014 12:46pm
5/29/2014 12:46pm Edited Date/Time 5/29/2014 12:46pm
JD sells a pretty cool jetting guide excel spreadsheet you can use to calculate jetting changes for $20.

I think it is only set up for keihin carbs so if you are running a mikuni or something you will want to look elsewhere.
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BAMX
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BAMX 5/29/2014 3:18pm
5/29/2014 3:18pm
I believe that I went -2 main, -1 pilot and up 1 clip last year. on my RM250
Falcon
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Falcon 5/29/2014 4:27pm
5/29/2014 4:27pm
What are you riding? NCY usually has a race support truck there and they post their jetting specs for all YZs. I ran their recommendation a few years back and it worked pretty well.

My advice is to buy at least one day of practice and use that as a jetting day. You'll learn a lot.

Also, you can buy pump gas in town and it is oxygenated for the altitude.
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DTHA70
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DTHA70 5/30/2014 7:25am
5/30/2014 7:25am
Falcon wrote:
What are you riding? NCY usually has a race support truck there and they post their jetting specs for all YZs. I ran their recommendation a...
What are you riding? NCY usually has a race support truck there and they post their jetting specs for all YZs. I ran their recommendation a few years back and it worked pretty well.

My advice is to buy at least one day of practice and use that as a jetting day. You'll learn a lot.

Also, you can buy pump gas in town and it is oxygenated for the altitude.
with abunch of shit additives in it. get the sx2 or MRX02 and call it a day man. the oxygenation in those fuels negates the loss in power.
adub274
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adub274 5/30/2014 9:34am
5/30/2014 9:34am
Falcon wrote:
What are you riding? NCY usually has a race support truck there and they post their jetting specs for all YZs. I ran their recommendation a...
What are you riding? NCY usually has a race support truck there and they post their jetting specs for all YZs. I ran their recommendation a few years back and it worked pretty well.

My advice is to buy at least one day of practice and use that as a jetting day. You'll learn a lot.

Also, you can buy pump gas in town and it is oxygenated for the altitude.
06' YZ 250 . The NCY rig sounds like the deal . I do remember seeing renegade or dragon selling race fuel in the pits a couple of years ago .
adub274
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adub274 5/30/2014 9:35am
5/30/2014 9:35am
BAMX wrote:
I believe that I went -2 main, -1 pilot and up 1 clip last year. on my RM250
That should give me a good baseline . Thank you .
BAMX
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BAMX 5/30/2014 12:59pm
5/30/2014 12:59pm
BAMX wrote:
I believe that I went -2 main, -1 pilot and up 1 clip last year. on my RM250
adub274 wrote:
That should give me a good baseline . Thank you .
I will check those tonight to make sure. I tried one main above and below 2 and both were giving me issues at the too of the uphill.

Also, I was running whatever the VP guy at the track had for 2 strokes.
BAMX
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BAMX 5/31/2014 6:02pm
5/31/2014 6:02pm
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas at Mammoth.

Normal
168
48
NECJ middle

Mammoth
162
45
NECJ up one from middle


adub274
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adub274 6/1/2014 8:31pm
6/1/2014 8:31pm
BAMX wrote:
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas...
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas at Mammoth.

Normal
168
48
NECJ middle

Mammoth
162
45
NECJ up one from middle


Perfect . That's what I was looking for .
bymcchancey
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bymcchancey 3/25/2023 7:39pm
3/25/2023 7:39pm
BAMX wrote:
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas...
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas at Mammoth.

Normal
168
48
NECJ middle

Mammoth
162
45
NECJ up one from middle


Hey, I know this is an old post. For mammoth what gearing did you run. Also when you say gas mix normal is that 32:1 ?

thanks…-R

BAMX
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BAMX 3/25/2023 8:24pm
3/25/2023 8:24pm
BAMX wrote:
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas...
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas at Mammoth.

Normal
168
48
NECJ middle

Mammoth
162
45
NECJ up one from middle


bymcchancey wrote:
Hey, I know this is an old post. For mammoth what gearing did you run. Also when you say gas mix normal is that 32:1...

Hey, I know this is an old post. For mammoth what gearing did you run. Also when you say gas mix normal is that 32:1 ?

thanks…-R

I used what I always used for gearing but going up one on the rear wouldn't be a bad to try.  From what I experienced, you are going to be at a disadvantage to the 4t's on the start and up the hill.  For the fuel mix, I used my normal 40:1 with Motorex Top Speed 2T.  I went from an 06 450 Honda to an 06 RM250.  Mammoth is the only place that I missed the 450.  The start is so important and it being so long made it hard.  Passing guys in the turns only to have them out drag race me back up the hill was frustrating.

bymcchancey
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bymcchancey 3/25/2023 8:52pm
3/25/2023 8:52pm
BAMX wrote:
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas...
Here is what I started with at normal SoCal tracks and ended up with at Mammoth. 06 RM250 w/race gas mix normal and full race gas at Mammoth.

Normal
168
48
NECJ middle

Mammoth
162
45
NECJ up one from middle


bymcchancey wrote:
Hey, I know this is an old post. For mammoth what gearing did you run. Also when you say gas mix normal is that 32:1...

Hey, I know this is an old post. For mammoth what gearing did you run. Also when you say gas mix normal is that 32:1 ?

thanks…-R

BAMX wrote:
I used what I always used for gearing but going up one on the rear wouldn't be a bad to try.  From what I experienced, you...

I used what I always used for gearing but going up one on the rear wouldn't be a bad to try.  From what I experienced, you are going to be at a disadvantage to the 4t's on the start and up the hill.  For the fuel mix, I used my normal 40:1 with Motorex Top Speed 2T.  I went from an 06 450 Honda to an 06 RM250.  Mammoth is the only place that I missed the 450.  The start is so important and it being so long made it hard.  Passing guys in the turns only to have them out drag race me back up the hill was frustrating.

Thank you. Yeah, I’ve only been up there with 450 the last couple years.. I’m racing 50c this year.. so i was hoping I have a chance at a bear… again thanks..-R ✌️

NITRODOG
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NITRODOG 3/29/2023 5:06pm
3/29/2023 5:06pm

Are they racing snowmobiles this year?

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