CMB 45RS remote needle mod?

[Sean Janne]

I bought a used CMB 45RS and was wondering what the best carb setup for it would be? To use the stock mixture adjustments or convert it to using a remote needle? If I understand it right, there's a high and low speed mixture adjustments on the carb? I'm not too familiar with this engine and can't find any owners manual for it.

 

[glenng]

The 45Rs has a low speed needle adjustment(the hex bolt on the side of the carb). I used one of Don's Jackrabbit Racing remote needle bases with a O.S. 40 A needle for high speed adjustments. Hope this helps.

 

[FloridaScaleBoater]

Glenn is correct, there is NO High Speed Needle in the carb, just a Low Speed.

You will need to use a needle in line from tank to carb, for high speed adjustment

 

[Buckshot]

Some have the high speed needle built into the carb along with the low speed needle. Like this:

If it fits in the boat with the High Speed needle mounted to the carb, run it as is.

 

[Sean Janne]

Some have the high speed needle built into the carb along with the low speed needle. Like this:

If it fits in the boat with the High Speed needle mounted to the carb, run it as is.

Mine must be an older version? It only as the fuel inlet fitting on that side of the carb.

So, the hex on the throttle linkage side of the carb is for low speed mixture, correct? What is the set screw and nut on top of the carb for?

I do have a remote needle that I used on my old K&B that ran between the tank and the carb, so I'll be ok using that as my high speed mixture adjustment?

 

[Buckshot]

Not necessarily an older version. I think 90% of these motors sold in the USA did not have the high speed needle installed on the carb as pictured above.

Yes the hex on the throttle arm side of the carb is the low speed adjustment.

There is a helix groove cut in the barrel of the carb and the "set screw" and nut you see on top is actually the pin that runs in this groove to move the barrel in and out of the carb body.This is how the low speed needle is operated when opening and closing the throttle.

You should be fine using the same remote needle as you did with your K&B.

 

[Sean Janne]

Awesome! Thank you all for your help! I'm going to bench test it today before heading to the pond this weekend!