Sharmcos.........folks put 45 webers on A14 race engines so 41mm carbs might be ok. Either set of carbs should work well. For street CV carbs are a little more user friendly as they are slightly more tolerant if the jetting is off. As for fuel consumption I couldn't give you a real idea as my car only sees the race track............so my 15 mpg isn't much of a guage since the motor is always between 4500 and 8600 rpms.

Lowtech I was looking at the Mikuni HSR carbs before I stumbled on to the FCR carbs with manifold. My thoughts were a set of HSR carbs would be a nice up grade over then Hitachi SU style carbs.

Tom

I found the slides have different mounting styles, the front set have a plate that screws down over the needle whereas the others have a retaining clip to keep a plate over the needle. Can't find my pliers to get them out :/

I am running two Mikuni HSR42 carbs. So far they are excellent! The Throttle response is awesome and no flat spots. Super easy to tune. Large float bowls and an accelerator pump. Fit on standard Mikuni, Weber or S.U. manifolds.......

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Thanks for the responses everyone. That is useful info.

I have a set of these carbs being the BS34 models which I believe were fitted to a Yamaha XS1100 from the late 70's perhaps early 80's. What I have come to learn about these carbs is that from the factory on some models they set the two centre carbs a bit richer by fitting slightly fatter jets, say 115 on the outers and 120 on the inners. No doubt because they get less air to cool them and so run them a bit richer to try to keep the temperatures under control.This no doubt varied from manufacturer to manufacturer so any set you consider these issues should be kept in mind.

Thats all well and good on an air cooled engine but not a factor on anything that is watercooled. The needle heights are adjustable and have 5 different settings and so should be set the same on the bench before fitting up to the car.

I was going to use the front set as it has the richest needles and smoothest action but I'll just transfer them over to one of the other carbs and build the manifold for that, there's 3 of those with the same spacing so they're probably Kawasaki or Yamaha ones, the black one in the front is off a Suzuki

Awww, I'm not a bum, it just takes me a while to get stuff done.

Keihin FCR uses a flat slide as the throttle valve, while the Keihen CVK is slide venturi with butterfly-throttle.

41 mm will likely be overcarbed for an A-series engine. 36mm carbs will make plenty of power for 1400-1500cc engines.

Rallytwit,

How do the Keihin FCR perform on the road compared to the CV type carbs, including fuel consumption?
I have Keihin CVK41 and FCR36, dunno which to use.

I've been running motorcycle carbs for a few years now. All you need is a fuel pressure regulator to limit it to 1.5 psi. I run a little bit less just on 1 psi. The float needles will seat at upward of 3 psi but it varies from carb to carb, stick to 1.5 and it will be fine.

As for the description flat slides are generally referring to mechanical operation to lift the slide versus a CV carb which uses a diaprhagm to lift the slide both types could have a "flat slide".

The CV type are a bit more,user friendly, a decade ago i ran a Yamaha 1000 powered single seat sports racer and it used CV style downdraft carbs which worked quite well. On my 1200 coupe I run the Keihin FCR flat slide carbs and they also are fantastic, as an motorcycle racer I am biased but I think bike carbs are better made and offer more performance

To,

Mikuni 34mm round slide carburetors



SUs also have a round slide (piston) along with a traditional butterfly throttle plate.