33mm Smoothbore carbs, round slide.

I bought a set of 33mm smothies, the old ones with the round slides. At first I was excited because they appeared to have the fuel injection pump set up. I thought this was a factory set up and I figured I had scored a rare set of carbs. Now that I have them apart, it is evident that it never worked right. The passageways from the bowl to the carb body were blocked off.

The rest of the carbs are salvagable, but maybe one of the bowls was swapped out for the modification. The bowl that the pump was mounted on doesnt match the other three. So that leaves me with questions for this forum:

1. Is there any change this was a stock feature from Mikuni?

2. What other carb uses the same bowl gasket footprint as the 33mm smoothbore(I am tring to understand where the bowl with the pump mount came from)?

3. Where can I find a float bowl for 33mm smoothies? Sudco doesnt carry them...

toddzilla1 wrote: I bought a set of 33mm smoothies, the old ones with the round slides. At first I was excited because they appeared to have the fuel injection pump set up. I thought this was a factory set up and I figured I had scored a rare set of carbs. Now that I have them apart, it is evident that it never worked right. The passageways from the bowl to the carb body were blocked off. The rest of the carbs are salvageable, but maybe one of the bowls was swapped out for the modification. The bowl that the pump was mounted on doesn't match the other three. So that leaves me with questions for this forum:
1. Is there any change this was a stock feature from Mikuni?
2. What other carb uses the same bowl gasket footprint as the 33mm smoothbore (I am trying to understand where the bowl with the pump mount came from)?
3. Where can I find a float bowl for 33mm smoothies? Sudco doesn't carry them...

Hello, toddzilla1, and WELCOME to KZr!

Mikuni 33mm smoothbores are imo too large for stock or modestly over-bored large four KZ's.
May perform okay at wot.
But likely difficult to achieve satisfactory idle and low rpm performance.
Regardless of pilot jet sizing and pilot crew adjustment setting.
Because the carb bore (throat) is just too large to gain sufficient venturi effect (air speed) at lower rpm due to the engine's inability to pump enough air.

Imo, the 29mm smoothbores are a better choice on anything close to stock and mild overbores.
And 33's are better suited to very large over-bored performance-built engines which may take advantage of and not be overwhelmed by the larger carbs.

There are several KZr threads about the 33mm smoothbore carbs.

The carb should perform without a functioning fuel pump apparatus (same as other similarly equipped carbs).

Mikuni smoothbores, 29's or 33's, were always an after-market accessory and were never offered as a factory option.

Good Fortune!

why do u need another bowl. why cant u just use that one ?

I have decided to use it, I have no choice. And while I am at it, I am gonna complete the injection system.

So, I have been told that these carbs are too much for my 1100cc engine. I am running a J model head on a KZ cylinder with mild cams. What is the best carb set up for this configuration?

Regards,

Todd

The 33s worked just fine in motors at least 1075cc.If you are running cams of .380 lift or larger than you should not have any problems. Even a .360 lift cam used to work fine with those carbs. They used to have a poor transition on motors that were smaller and did not draw enough.

i ran them on my 1135cc with kz head , 37.5 valves and .424" lift cams. they run great, but like any big manual slide carb, u cant wack the throttle from below 35/4000rpm's or it will bog. that is completely normal and ok.
i use RS34's now on my 1200cc and they act the same.