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Thread: Jetting Database

  1. #11
    Junior Member hefnerconstructionlc's Avatar
    Join Date
    Sep 2010
    Sublette, KS
    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

  2. #12
    Member riversidenix's Avatar
    Join Date
    Feb 2012
    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'

  3. #13
    Junior Member Rayburn11's Avatar
    Join Date
    May 2012

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

    I just installed a 39mm on my R
    Quote Originally Posted by Ryan View Post
    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

  4. #14
    Senior Member Scicchi's Avatar
    Join Date
    May 2011
    Coal Region of PA

    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): 1

    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 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 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 1 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.
    Last edited by Scicchi; 10-01-2012 at 07:30 AM. Reason: Added updated info

  5. #15
    Senior Member mwiley's Avatar
    Join Date
    Jun 2012
    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
    Last edited by mwiley; 09-29-2012 at 07:42 PM.

  6. #16
    Senior Member pantera1975's Avatar
    Join Date
    Aug 2010
    Ripon WI
    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
    1986 ATC 250R built to trail ride!! Billet,chrome completly redone everything and LED built 330 motor. It rips now
    1985 ATC 250R PSI Racing pipe and porting stock motor built by BHP .

  7. #17
    Junior Member yaitsmy250r's Avatar
    Join Date
    Aug 2012
    310 pv with 38mm carb and a airbox elimantor kit set up to run from esr running 32 to 1 ?

  8. #18
    Senior Member Scicchi's Avatar
    Join Date
    May 2011
    Coal Region of PA
    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!
    Have a jetting combination that works? Add it to's Jetting Database and help another member out!

  9. #19
    Banned 05450r's Avatar
    Join Date
    Aug 2011
    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
    Scicchi likes this.

  10. #20
    Junior Member crager's Avatar
    Join Date
    Sep 2013
    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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