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1999 kx250 expansion chamber differences.

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Does anyone know the actual differences between the stock chamber and the FMF gnarly? Advantages or disadvantages? Or if anyone has ran different pipes and has any helpful findings. Thanks.

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Gnarly shifts the power down lower in the rev range 

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So is the stock chamber better overall for the entire Power Band? Or does it still sign off early on top?

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Better overall in my opinion.  Will have a lot more on top than a gnarly.  You'll have the bike to see if its got enough top end for you.  Those motors run best in the low-mid range.  The top end is pretty good but in stock form its mostly tuned for midrange thrust.

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Better overall in my opinion.  Will have a lot more on top than a gnarly.  You'll have the bike to see if its got enough top end for you.  Those motors run best in the low-mid range.  The top end is pretty good but in stock form its mostly tuned for midrange thrust.


Ok thanks for all the responses. I appreciate the help.

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On 6/4/2017 at 1:57 AM, turbo dan said:

Better overall in my opinion.  Will have a lot more on top than a gnarly.  You'll have the bike to see if its got enough top end for you.  Those motors run best in the low-mid range.  The top end is pretty good but in stock form its mostly tuned for midrange thrust.

wish i could try a stock pipe one day , i bought my bike with the gnarly already on it , i do like how it tractors along low in the rev range tho

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wish i could try a stock pipe one day , i bought my bike with the gnarly already on it , i do like how it tractors along low in the rev range tho


Do you think there would be any jetting changes needed going from a gnarly to a stock pipe?

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1 hour ago, OneLung said:

 


Do you think there would be any jetting changes needed going from a gnarly to a stock pipe?

 

doubt it , if anything maybe an air screw adjustment

what jetting you got in the bike now ?

 

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Year: 1999
Model : KX250
Displacement (cc): 250cc
Carb size (38 or 36mm): PWK38S (stock)
Slide: #7
Main jet: 155
Pilot Jet: 45
Air screw (turns out): 1 1/8 winter 1 1/2 summer
Needle model/Clip position: n3wk 3rd position
Altitude where you ride: 0-800 ft Michigan
Temperature: winter ( winter (50f) /summer (95 f)
Reeds: boyesen power reeds stock cage
Pipe/silencer: fmf  gnarly / fmf turbine core
Head mod: stock
Other mods: #58 power jet
Type of fuel: 93 octane 32:1 honda HP2 (I had a whole case left from last bike, dont judge!)
Where in the powerband do you ride (Lugger - for technical stuff, or wide open - desert / MX): 50/50 bottom and top
Degree of satisfaction: 75%???
And finally: how much spooge 1) none, 2) little, 3) medium, 4) lots: 2

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9 hours ago, OneLung said:

Year: 1999
Model : KX250
Displacement (cc): 250cc
Carb size (38 or 36mm): PWK38S (stock)
Slide: #7
Main jet: 155
Pilot Jet: 45
Air screw (turns out): 1 1/8 winter 1 1/2 summer
Needle model/Clip position: n3wk 3rd position
Altitude where you ride: 0-800 ft Michigan
Temperature: winter ( winter (50f) /summer (95 f)
Reeds: boyesen power reeds stock cage
Pipe/silencer: fmf  gnarly / fmf turbine core
Head mod: stock
Other mods: #58 power jet
Type of fuel: 93 octane 32:1 honda HP2 (I had a whole case left from last bike, dont judge!)
Where in the powerband do you ride (Lugger - for technical stuff, or wide open - desert / MX): 50/50 bottom and top
Degree of satisfaction: 75%???
And finally: how much spooge 1) none, 2) little, 3) medium, 4) lots: 2

have you thought about trying a suzuki needle ?

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have you thought about trying a suzuki needle ?


I haven't. What would that do for me and what else would I have to change to be tuned. I feel like the bike does run pretty good. But I'm always open to new ideas and suggestions.

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cleans up the bottom end and makes bike lug down low really well

your pilot and main would be good

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Ok that sounds like fun. What needle are we talking about and what clip position should I start at?

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2 hours ago, OneLung said:

Ok that sounds like fun. What needle are we talking about and what clip position should I start at?

temps and elevation ?

summer and winter

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temps and elevation ?
summer and winter


Winter 50 F

Summer 90 F

0-800 ft

Thanks!

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45 pilot

65-90  nedj clip 2

below 65 necj clip 3

your main should be good

 

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18 minutes ago, MudBug20 said:

Will the zuki needle mod work on a 01?

definately

read my post above 

i will post part numbers for needles soon

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definately
read my post above 
i will post part numbers for needles soon

Awesome, thanks man

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