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mattcfish wrote:Are Mikunis that much better than Delortos? We're talking about flat slide Mics, right? I love the Dells but they are certainly sensitive.

they could out perform the Dels but remember Mikuni has no pumper...............

but then Bings don't eather......
We Americans tend to over carb and I read a lot of information to the idea of smaller carbs more suited to motor cc or inches

a CV can make a ride smoother as its not as sentive to movements or as I say a 3/10 slower of reaction

a slide or flat slide is 3/10th faster and more sentive

with my Current Mikuni I have no pre warm up for the carbs to work and bike will start with 1 kick or 1/2 roll of starter

Hello, new to the board. I found this thread interesting..

I installed mikuni 32's on my 75/7 when I redid it last winter. Starts better, runs faster, seems crisper and it does burn more gas. There is not a huge difference unless your wicking the throttle hard. I rode from Bellingham to Denver over a 3day period at an highway avg of 60 mph... most were whipping by.. but I enjoyed the fine ride. I got a consistent 42 to 45 mpg for the whole trip. As I gained altitude, I did notice some loss of power, however the starting was never an issue.
It was about a 1/2 spin on the button and bang, we were on. I have my old bings, ( rebuilt ) but I am not putting them on.
The bike was tuned for sealevel and is now in Denver and runs just fine.

I would recommend them if you are thinking of changing.

One caution, they may have problems passing an emission test.

We don't have that kind of testing where I live. They are not allowed on street machines in California.
My bike is registered in Alaska.

Jim,Ketchikan, AK

Bings dont need a pumper , they automatically enrich the mixture in transition.

When you open the butterfly this increases air flow, but the piston does not move as quickly as the butterfly, mainly because there is a spring above it which slows it down.

So the increased air flow through the relatively unchanged gap below the piston results in more suction at the needle jet, ant a richer mixture until the piston catches up with the butterfly.

Some folks think that selecting the correct spring above the piston is one of the secrets of tuning CV carbs.
SU have a choice of eight springs , and they fit Bings.
Most people report an improvement with the later Bing spring which is slightly stiffer than the early one.

Roy Gavin wrote: Some folks think that selecting the correct spring above the piston is one of the secrets of tuning CV carbs.
SU have a choice of eight springs , and they fit Bings.
Most people report an improvement with the later Bing spring which is slightly stiffer than the early one.

My early bings have no spring at all, and I have considered adding them for the reasons Roy states.

Has anyone tried this, and what springs have you tried?

[quote="gertiektn"]Hello, new to the board. I found this thread interesting..

I installed mikuni 32's on my 75/7 when I redid it last winter. Starts better, runs faster, seems crisper and it does burn more gas. There is not a huge difference unless your wicking the throttle hard. I rode from Bellingham to Denver over a 3day period at an highway avg of 60 mph... most were whipping by.. but I enjoyed the fine ride. I got a consistent 42 to 45 mpg for the whole trip. As I gained altitude, I did notice some loss of power, however the starting was never an issue.
It was about a 1/2 spin on the button and bang, we were on. I have my old bings, ( rebuilt ) but I am not putting them on.
The bike was tuned for sealevel and is now in Denver and runs just fine.

I would recommend them if you are thinking of changing.

Great info Jim. Thanx

The carb settings on the bikes without springs are different from the bikes with them.

Try the springs and dropping the needle a notch - but be prepared to change the needle and needle jet.

If you get it right it will make a difference- I did it on my R75 and was pleased with the result.

Dougie wrote........P.S. Classic mistake made with Mikunis is choosing units that are too big.


My question.....so what is the correct size Mikunis for a stock 81RS?

CafeRS wrote:Dougie wrote........P.S. Classic mistake made with Mikunis is choosing units that are too big.


My question.....so what is the correct size Mikunis for a stock 81RS?

I have not installed Mikunis on an airhead, but if I do on my R100, I will use 34mm.
Perhaps someone who has done it can give more insight.

Yep 34mm from my notes for a R100 RS

I have used 38mm round and flat slide Mikuni carbs on several R100's solo and sidecar outfit with success.
36mm is the smallest I would run on a 1000cc motor.