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Discussion Starter #1
Information posted by ~Dee~

My typical reply to jetting questions:

(1) Check your intake boot for leaks!
(2) Check for cylinder leaks since head has been shaved.
(3) Are the reeds in good condition?
(4) How does your plug look?
(5) If your carb is pissing fuel the float is not set correctly.

Many people say this:
air screw - idle to 1/16 throttle
pilot - 1/16 to 1/4 throttle
needle - 1/4 to 3/4 throttle
main - 3/4 to WOT

BUT the range of the jets actually overlap.

Air screw - off idle to about 1/4 throttle
The air screw meters air to the pilot jet

pilot - 1/8 to 1/2 throttle (changes to pilot affect the needle and main jet settings since it adds adds fuel during the midrange and topend)

needle - 1/8 to 3/4 throttle
an actual needle change will affect 1/8 to 3/4 throttle
clip changes afffect 1/4 to 3/4 throttle

main - 1/2 to full throttle


I saw this posted a couple sites and I think it would be an excellent addition to this site!

Each post should contain the following information:

Mixture ratio and fuel:

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?)

Main Jet size:

Slow (pilot) Jet size:

AirScrew (number of turns out):

Needle (what groove is the clip in, Brand, etc):

Reed brand and type:

Airbox: List any mods to include filter

Pipe: What brand and type

Engine Displacement: What size is it (250-265 etc.) and who's kit (ESR,etc) and PV or NON-PV.

Compression ratio:

Porting type:

Altitude: where you normally ride
 

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Discussion Starter #2
information posted by ~Dee~

My Example that has been tested!!


Mixture ratio and fuel: 40:1 HP2 with 100RON (95 octane)

Carb Type: 39mm Air Stryker

Main Jet size: 160 (starting point)

Slow (pilot) Jet size: 50 (starting point)

AirScrew: 2 turns out

Needle: DGH needle, middle clip position

Reed brand and type: CR250 cage with unknown fiberglass reeds and 5mm

Airbox: CFM Aluminum without cover and Uni filter

Pipe: CT midrange pipe

Engine Displacement: Non-PV CT 257cc

Compression ratio: unknown but stock type with 21cc Coolhead dome

Porting type: Nationals MX

Altitude: 50ft above sea level but sometimes as high as 500ft above sea level
 

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Discussion Starter #3
information Posted by ~Geeker~

Mixture ratio and fuel:

86 octane pump gas, oil ratio about 25-35:1 premix, AF ratio probably about 16:1

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?)

Stock '86 Keihin PJ, bored from 34 to 36mm

Main Jet size:

132

Slow (pilot) Jet size:

35

AirScrew (number of turns out): 3/8 from fully closed

Needle (what groove is the clip in, Brand, etc):

stock needle, lean clip

Reed brand and type:

Barnett fiberglass reeds & stock reed cage, w/o retainer

Airbox: List any mods to include filter

Stock, UNI w/o outerwear

Pipe: What brand and type

Paul Turner II

Engine Displacement: What size is it (250-265 etc.) and who's kit (ESR,etc) and PV or NON-PV.

Stock 250, stock bore and stroke, Geek built

Compression ratio:

stock (8.4:1 I think)

Porting type:

a little smoothing with a Dremel

Altitude: where you normally ride

1000-2000
 

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Discussion Starter #4
information Posted by ~Prednizone~

If there's anyone out there who's bike is still a 250, this could help. tongue.gif

Mixture ratio and fuel: 32:1 on pump gas

Carb Type: Keihin 39mm PWK

Main Jet size: 168

Slow (pilot) Jet size: 55

AirScrew (number of turns out): 1-3/4

Needle (what groove is the clip in, Brand, etc): DGK 2nd clip

Reed brand and type: iduno

Airbox: none...alum. elim. bracket and uni-filter

Pipe: CT "midrange" w/ FMF "Q" silencer

Engine Displacement: stock...250 non-PV

Compression ratio: stock

Porting type: none

Altitude: approx 1200ft (Phoenix area)
 

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Lots of good info Thanks

Ive Had quads, and been working on my own for quite awhile. Sometimes jetting still stumps me from time to time :huh:
 

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Mixture ratio and fuel: Cam-2 (114 octane)/Klotz red label 40:1

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?) Keihin PJ 36mm

Main Jet size: 148

Slow (pilot) Jet size: 50

AirScrew (number of turns out): 1 ½ - 1 ¾

Needle (what groove is the clip in, Brand, etc): 3rd groove

Reed brand and type: Boyesen Rad Valve

Airbox: List any mods to include filter: Stock box with Uni Filter

Pipe: What brand and type FMF Fatty with modded KX250 silencer

Engine Displacement: What size is it (250-265 etc.)

and who's kit (ESR,etc) and PV or NON-PV. Stock bore

Compression ratio: stock

Porting type: stock

Altitude: where you normally ride 800ft- 3000ft
 

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1988 trx250r
stock?
I have a 1986 stock cyl on a 1988 bottem end no porting done to it at all.
34mm kiehin carb
K&N filter cone type?
no lid on air box
psi pipe dont know what type lable is missing but it is large and section welded type w/psi silencer on the end
br8es plug
carb says PJ03AWYG on it
162 main jet (it had 152)ran like crap
58 pilot (it had a 42)ran like crap
needle is a NR1468 still in it and sudco says it should be a DGW?
air screw 3/4 turn out
needle in the 3rd position
I had the stock reed cage and metal reeds
Now it has new boysen reeds and just added a reed spacer (I hope this stuff helps)
not the carbon fiber ones
I live at 960 FT in MN and today it was 60F
145 -148 psi comp wot many kicks
can anyone help with the jetting for this thing? does not stay ideling for long
revs right from idel
then bog
then mid range picks up
then gets to lower range of high rpm well and then runs out on top end again????WTF
 

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1988 trx250r
stock?
I have a 1986 stock cyl on a 1988 bottem end no porting done to it at all.
34mm kiehin carb
K&N filter cone type?
no lid on air box
psi pipe dont know what type lable is missing but it is large and section welded type w/psi silencer on the end
br8es plug
carb says PJ03AWYG on it
162 main jet (it had 152)ran like crap
58 pilot (it had a 42)ran like crap
needle is a NR1468 still in it and sudco says it should be a DGW?
air screw 3/4 turn out
needle in the 3rd position
I had the stock reed cage and metal reeds
Now it has new boysen reeds and just added a reed spacer (I hope this stuff helps)
not the carbon fiber ones
I live at 960 FT in MN and today it was 60F
145 -148 psi comp wot many kicks
can anyone help with the jetting for this thing? does not stay ideling for long
revs right from idel
then bog
then mid range picks up
then gets to lower range of high rpm well and then runs out on top end again????WTF
I had an '86 cylinder on my 89'bottom end. the bore was fresh at .080 on a new bottom end also. Exaust was an FMF Fatty w/Boyeson Rad valve. Stock carb. I kept the slow jet at a #45, stock needle with clip in slot 4 from top of needle. and my main was a #158. Air filter was a K&N.Mine would idle all day. I didn't get to exactly break in the new bore before I put on an '89 jug but my setup should be a good starting point it ran fine but could have been better. I think more breaking in could have helped but I'll never know.My elevation was at sea level in s.e. WI. Give it a try.
 

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I had an '86 cylinder on my 89'bottom end. the bore was fresh at .080 on a new bottom end also. Exaust was an FMF Fatty w/Boyeson Rad valve. Stock carb. I kept the slow jet at a #45, stock needle with clip in slot 4 from top of needle. and my main was a #158. Air filter was a K&N.Mine would idle all day. I didn't get to exactly break in the new bore before I put on an '89 jug but my setup should be a good starting point it ran fine but could have been better. I think more breaking in could have helped but I'll never know.My elevation was at sea level in s.e. WI. Give it a try.
Mine sounds similar to yours, '89 bottom, '86 cylinder, stock everything else, reeds, pipe. Mine sits pretty well with a 42 pilot, 155 main, 4th clip groove from bottom of needle, 1 1/2 turns out on air screw. I have a bog on the bottom I'm trying to get rid of right now. Runs like a 125cc, but once the powerbank kicks in...hold on. Mine idles great. Will hold a very low idle. I'm around 700' here in Texas. Set at 70 degree temp. I think I may need to go up a bit on my pilot and in a bit on the air screw to fix my prob but it's me nit-picking more than anything. It really runs like a champ.
 

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Mixture ratio and fuel: 40:1 vp110: castor 927

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?) ESR 40.5 mm

Main Jet size: 180

Slow (pilot) Jet size: 50

AirScrew (number of turns out): 1.5

Needle (what groove is the clip in, Brand, etc): middle DEG

Reed brand and type: Stock

Airbox: K and N no lid no snorkle

Pipe: FMF Gold series Fatty

Engine Displacement: ESR 310 (1st bore 293cc)

Compression ratio: 210 PSI

Porting type: TRX 9 (dune port)

Altitude: 500'-2000'

main jet is too fat need to come down to probably closer to a 170-172 and change the needle to a DGH or CEL
 

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Mixture Ratio and Fuel: 32:1 Klotz Techniplate 110 Leaded Race Fuel
Carb Type: Mikuni, Keihin (PJ, A/S, etc.) Keihin PWK 38 mm
Main Jet size: 180
Slow (pilot) Jet size: 58
AirScrew (number of turns out): 1.75
Needle (what groove is the clip in, Brand, etc): 3 position
Reed brand and type: VForce 3
Airbox: K&N with Outerwear, No lid on box with and outerwear for lid, No snorkel
Pipe: CT Midrange
Engine Displacement: BDT 330 1st bore
Compression ratio: 200
Porting type: Midrange port
Altitude: 1500 - 3000 feet
 

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Mixture ratio and fuel: 32:1 cam2 110: HP2

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?) Keihin 40.5 mm

Main Jet size: 195

Slow (pilot) Jet size: 55

AirScrew (number of turns out): 2.5

Needle (what groove is the clip in, Brand, etc): 2nd from taper CGL

Reed brand and type: boysen

Airbox: K and N no box or lid.

Pipe: FTZ Drag

Engine Displacement: 370cc

Compression ratio: unknown

Porting type: drag

Altitude: 604'
 

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Ryan, could you shoot me a email, rayburn in Iowa

I just installed a 39mm on my R
Information posted by ~Dee~

My typical reply to jetting questions:

(1) Check your intake boot for leaks!
(2) Check for cylinder leaks since head has been shaved.
(3) Are the reeds in good condition?
(4) How does your plug look?
(5) If your carb is pissing fuel the float is not set correctly.

Many people say this:
air screw - idle to 1/16 throttle
pilot - 1/16 to 1/4 throttle
needle - 1/4 to 3/4 throttle
main - 3/4 to WOT

BUT the range of the jets actually overlap.

Air screw - off idle to about 1/4 throttle
The air screw meters air to the pilot jet

pilot - 1/8 to 1/2 throttle (changes to pilot affect the needle and main jet settings since it adds adds fuel during the midrange and topend)

needle - 1/8 to 3/4 throttle
an actual needle change will affect 1/8 to 3/4 throttle
clip changes afffect 1/4 to 3/4 throttle

main - 1/2 to full throttle


I saw this posted a couple sites and I think it would be an excellent addition to this site!

Each post should contain the following information:

Mixture ratio and fuel:

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?)

Main Jet size:

Slow (pilot) Jet size:

AirScrew (number of turns out):

Needle (what groove is the clip in, Brand, etc):

Reed brand and type:

Airbox: List any mods to include filter

Pipe: What brand and type

Engine Displacement: What size is it (250-265 etc.) and who's kit (ESR,etc) and PV or NON-PV.

Compression ratio:

Porting type:

Altitude: where you normally ride
 

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Mixture ratio and fuel:
32:1 Maxima Castor 927 w/Sunoco 112 octane

Carb Type: Stock Keihin PJ 34mm

Main Jet size: 158

Slow (pilot) Jet size: 45

AirScrew (number of turns out):

Needle (what groove is the clip in, Brand, etc): DGH 3rd clip

Reed brand and type: V-Force 3

Ignition: Brand new OEM CDI and coil, new NGK plug boot, all electics checked with a multimeter per Honda manual.

Spark Plug: NGK BR8ES gapped at .022

Airbox: Twin Air in stock air box w/lid and snorkel

Pipe: Stock

Engine Displacement:
254cc(67mm Wiseco)

Compression ratio: unknown

Porting type: bare basic just to clean things up

Altitude: Less than 1000ft

Temp when tuned: 68°

Notes:Started out breaking the top end in jetted super rich with a 168 main jet and a 50 pilot. After break-in, I came down on the main jet one by one. With a 168 and 165, anything over ¾ throttle would just break up and sputter badly(expected). I also put in a 48 pilot but it was still rich as evident of the air scew having to be turned out about 2 ¾ turns . Dropped the main jet to a 162 and the top end started to come around and the exhaust tone began to lose it's "flatness" and started sounding crisper. Did the first plug chop with a 160 main and the plug was still quite wet with it still breaking up on the top end in the lower gears a little. Finally settled(until I can get out and do a chop again) on a 158 main and a 45 pilot with the highest idle being 1¼ turn out on the air screw. With this set up, idle is great, smokes MUCH less then the previous pilots, much(not all) of the stumble when putting around with the throttle just barely cracked is gone and power is smooth from just off idle right up through the top end. I suspect it may still be rich a tad and I will do a plug chop to verify, but that's fine with me.

Update I did a plug chop and confirmed that it is indeed rich at this set-up but just slightly. Good incase the temp drops another 15-20 degrees. In the hot summer, I may put in a 155 main jet and do another chop just for curiousity.
 

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Mix= 32:1 amsoil/112 Dragon
Carb= 38mm Air stryker
Pipe= LRD Adjustable with FMF quiet core silencer
Air box= Unifilter with slots milled in airbox lid
Reeds= Boyseen Rad valve
Bore= 67.25/255cc
UCCR= 14.85/1
Compression= 230psi
Porting= Sometype (not sure what rpm range)
Altitude= 850ft
Main jet= 178
Slow jet= 50
Air screw= 2 turns out
Needle= CEJ with clip in 3rd position
Temp= 65 degrees
Spark plug= BR8ES gapped at .022
 

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1986 ATC 250R
esr 330 non pv trx 9
long rod crank
esr ATC pipe and silencer
v force reeds
full air box with no lid and uni filter
39mm kehin
1.5 air screw
center clip with cel needle
52 slow jet
188 main (good for 80 deg plus
stock ignition
500 feet up to 1500 in Wisconsin
 

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310 pv with 38mm carb and a airbox elimantor kit set up to run from esr running 32 to 1 ?
I think the Jetting Database is more for information on what is known to work on what set-ups to give you an idea of where to start, not so much to ask about jetting.

For instance, this may give you a general starting point:

Mixture ratio and fuel: 40:1 vp110: castor 927

Carb Type: Mikuni, Keihin (PJ, A/S, etc.) (what bore is the carb?) ESR 40.5 mm

Main Jet size: 180

Slow (pilot) Jet size: 50

AirScrew (number of turns out): 1.5

Needle (what groove is the clip in, Brand, etc): middle DEG

Reed brand and type: Stock

Airbox: K and N no lid no snorkle

Pipe: FMF Gold series Fatty

Engine Displacement: ESR 310 (1st bore 293cc)

Compression ratio: 210 PSI

Porting type: TRX 9 (dune port)

Altitude: 500'-2000'

main jet is too fat need to come down to probably closer to a 170-172 and change the needle to a DGH or CEL
Or you can always ask in the general Intake and Fuel forum.

Hope this helps!
 

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Mixture ratio and fuel: 32.1 vp c12 HP2 oil

Carb Type: 38 pwk a/s

Main Jet size: 172 and 175 depending on temp

Slow (pilot) Jet size:52

AirScrew (number of turns out):1.5-1.75 out

Needle (what groove is the clip in, Brand, etc): Dgl needle,2nd from bottom

Reed brand and type: Boyesen valve and fiberglass reeds

Airbox: 06 450r Venom? air box eliminator with Uni filter,No-Toil oil

Pipe: Sparks Mx

Engine Displacement: 265cc non-pv

Compression ratio:230psi

Porting type:HPR mx

Altitude: 600-700 ft above sea level

Cr250 ignition,Br8es at .22 gap
 

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Mixture ratio and fuel: 40:1 93 oct

Carb Type: Keihin PJ 34

Main Jet size: 160

Slow (pilot) Jet size:48

AirScrew (number of turns out):1 3/4

Needle I don't know 3rd clip

Reed brand and type:boyesen as

Airbox:Unifilter no lid

Pipe: fmf fatty

Engine Displacement: 249 / 66.75 NON-PV

Compression ratio: I don't know. Squish is .075 3 piece head gasket

Porting type:mild

Altitude: 900-1500
 
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