Mikuni Keihin Hitachi home
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Keihin (it's "kayheen" with accent on second syllable )

Unlike other jet companies (dj, rd, keyster), Factory Pro Replica jets, Keihin and Mikuni, follow the original manufacturer's size scale so the Factory Pro Replica jets are interchangeable with original jets - saving a lot of time and improving accuracy for a good tuner.

Pilot jets
(aka "slow jets") Keihin
Keihin

21 series

 

OEM Honda CV carbs

We either have OEM or we make Factory Pro replicas

 
Keihin

22 series

  We have OEM Keihin  
  Keihin

25 series

 

OEM Kaw CV carbs
FCR "Flatslides"

We either have OEM or we make replicas

 
  Keihin

26 series

  OEM Honda dirt bikes w/ CV carbs +

We have OEM

 
 
Main jets, Keihin
( say "Kayheen")
  Keihin

393 series

"Kayheen"
"small, round, slotted"

most OEM CV carbs

We have:
50 to 250 (larger than Keihin's 225!)
  Keihin

357 series

"Kayheen"
"long hex jets"

almost every FCR and CRS Smoothbore or Flatslide carb

 
         

tIdentify emulsion tubes and needle jets, Mikuni

Identify Yamaha Virago emulsion tubes and needle jets

Identify Honda VTR1000 emulsion tube / needle jet front and rear

needles

Keihin
FCR Flatslide needles
    FCR and Smoothbores only I got really tired of trying to use the original Keihin numbering / profile codes, so I made my own.
Very nice if you have everything perfect at every throttle position except for 1/4 and only want to change that 1 thing! 
Flatslides are super easy to tune on the EC997 dynos and not easy on anything else for many different reasons.

needle shims

Emulsion Tubes, HDJ

emutube2.gif (588470 bytes)

note the fuel droplets at the backside of the needle.

emuhidisp.gif (281690 bytes)

note the white spray at the backside of the needle.

patented High Dispersal Jet System
HDJ

 available for licensing
Easily retrofitable in many OEM Keihin, Mikuni and aftermarket carbs and simple to make minor modifications in manufacturing process to incorporate.
Significantly better fuel atomization, runs without misfire at leaner fuel delivery rates, better power from the same amount of fuel, more consistent, smooth running, as verified on
EC997 Low Inertia dyne FLUX value engine smoothness testing. I can explain that if you are not using that dyne system and cannot get that data.
All what an MJN promised, but it can run cleanly at all rpms and, because it still used a tapered needle, is easy to tune properly.

main jets

Main Jets

STYLE Slang.... Where usually used Notes
"Keihin style"
mfg by Factory Pro.
Uses the same number size scale as original Keihin jets.
393 Series
(5x.75 thread)
Commonly known as:
"Small, round, slotted"
used in original equipment CV carbs on Honda, Kawasaki, Keihin equipped Triumph and some Yamaha Range:
 We make larger upper range and lower smaller range than usually available from importers:

#50-#200 in 2.5 increments:
#205 to #250 in 5 increments
"Keihin style"
mfg by Factory Pro.
Uses the same number size scale as original Keihin jets.
806 Series
(6x1.00 thread)
Commonly known as:
"the big thread, round jets for the HD"
Used only in original HD and some European 94-97 ZX9 carbs as far as I can see. Range: larger upper range

#160 to #200 in 2.5 increments
#205 to #250 in #5 increments

"Keihin style"
mfg by Factory Pro.
Uses the same number size scale as original Keihin jets.
357
"Hex" Series
Commonly called "Keihin Hex jets" Used in most Keihin FCR's, Smoothbores and some dirt bikes.  

carb tools

Mikuni Needle Jets / Emulsion Tubes

UNDER CONSTRUCTION!!!!

 

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