Revision as of 02:22, 24 September 2013

Motorcycle carbs, bike carbies. Flat-slide, constant vacuum or variable venturi carburetors.

1 Overview
2 Adapter Kits
- 2.1 Fumiya Kit
3 Keihin FCR
4 Matsuoka MSR
5 Mikuni
6 Photo Index
- 6.1 Uploads

Overview

TUNING is critical. Bike carbs as-is run poorly on automotive engines. But with the right jet or needle selection they can run very well.

Keihin Flat CR (FCR)

bike carbs on A12Y engine

Matsuoka MSR carbs

adapt carbs from your favorite motorcycle

Suzuki GSX-R (aka GSXR)

Yamaha YZF-R1 (aka R1) carbs are a fad in USA as of 2012.

ヤマハ

Adapter Kits

Fumiya Kit

Datsun 1200 enthusiasts Fumiya sells these

Keihin FCR

rallytwit made 73.22 RWHP on his A-series.

39mm FCR carbs with a near standard GX motor; ported head, headers 2 inch exhaust and 14lb flywheel. As far as reliable FCR carbs are stone axe reliable. For street (or racing) use you would have to do some tuning but it's not a big deal. I only needed an hour of dyno time to get the car 95% dialed. My only problems were because the carbs were on 175HP A-series powered sports racer so the jets were way off what my motor needed............lots of guys use these on street bikes and they are standard equipment on MX bikes. 32MM would likely be better for a street car, the 39's on my car border on over-carbed. As fars as how the motor runs they are the bomb the motor sings......revs like mad and instant throttle response.

Matsuoka MSR

Matsuoka MSR are like FCR but about $1000 US cheaper. They use the same sliding throttle valve design. They're made by Mikuni. Manifold can be any DCOE (Weber/Dellorto/Solex) type.

new, jetted to your spec: 96K yen (1230 AUD) or with manifold and linkage closer to 200K yen.

Feral said:

When I say just about as good as injection I mean the low speed response from the Mikuni flat slides is incredible. It will still not be as accurate as any well laid out injection system, but really do work very well

Mikuni

Mikuni also made constant velocity (CV) carburetors. The venturi size is what sets the HP characteristics. The bore size is larger and has less effect on HP (as with any carburetor).

Mikuni BS series. For example 1980- Suzuki GS1000 came with BS34 carbs (34mm) for 90 HP. A 1981 Kawasaki KZ1000 fitted with BS34s made 102 HP.

Mikuni BS series "Round Slide"
variable venturi
constant velocity design

These being CV carburetors are similar to SU carburetors. They have a traditional butterfly throttle but the actual airflow is controlled by the round slide (piston) that floats up by vacuum action. It is opposed by the dome spring.

Mikuni VM - late model series http://www.mikuni.com/pdf/vmmanual.pdf