Need help with CMB Carb.

[nitrotoys]

HI all, looking for help.

I got a new CMB carb, it came with one inlet fuel port, just streight in to carb.

then it came with a seperate needle valve.

which one am i to use?

or which is best to use?

and what is the running temps of a .21

and needle adjustments?

thanks for all the info.

Tom

 

[waterbug]

NT,

You use both !!!! The straight one on the carb stays there, then you run one line to the other valve.[remote needle valve] Then hook the line from the tank to the bottom outlet. this is the needle valve to adjust the fuel flow !! Also put a fuel filter in the line from the tank before the remote needle valve. Keep the line from the carb to the valve about 1 1/2" long.

Some of the guys will have a picture they can post I know !!!!

Start with the needle at 4 turns out it should run there but will not idle. So keep up the R's. Take it to the pond to do this so you can launch the boat and run it in the water !! Run out 2 tanks, then start to lean out the needle a 1/4 to1/2 turn each tank after that. When it startes to lean out the rev's will go up and the speed will increase. A this point run 2 tanks at this setting. Know if you have a temp gun you want the temp to be at 210*-200* you should have run 8 to 12 tanks by know. Once you get the temp at 200-210* run one tank at this temp . Then rich'in needle 1/2 turn and run1/2 tank, bring it in and lean it out the 1/2 turn you shold be good to go then. Ideal temp would be about 220*-230*. AT THE MOST !!!

The guys that run this engine can be more precise than I can. ;D

 

[nitrotoys]

Hey waterbug,

Its NOT a remote needle valve. Its got threads and a jam nut on one end and the other has a fuel in and then the slotted needle adjustment.

thanks

 

[waterbug]

OOOOOOPPPSSS!!!!!!!!!! Do you have a remote needle you can use ??? If not then you take out the nipple and put in the needle assembly. Close the carb fully closed .

Most of the time I losen the needle from the bottomed out position about 2 1/2 turns then put the assembly in until it stops. Then back off with the nipple pointing down or in the open, tighten the jam nut.

 

[nitrotoys]

Waterbug,

 

[nitrotoys]

Waterbug,

Sorry bud, Spoke to soon, was trying to go off memory instead of running out and looking at it, IT IS a REMOTE NEEDLE VALVE, Sorry for the mix up.

Now the carb looks to have a lowspeed needle, am i right?? Do i touch that, it seems real hard to turn, i didnt turn it. Its a knurled peice with the rotor arm.

whats a good % nitro the .21s like for just sport running, not racing? am thinking around 40%.

thanks for the info again waterbug

 

[waterbug]

It should be set at the factory. Don't touch !!! I would say 20 to 40% is ok for sport. I'm assuming its a CMB engine.