Radne Raket 85, User Manual

6

Users Manual

6

Carburettor setting

If you mounted the engine on the kart according to the description, 

you are now ready for your first test run. Select a “normal” gear-

ing. We suggest 11 teeth on the engine sprocket (this is standard) 

and 80 teeth on the rear axle sprocket, this we call 11:80 gearing. 

Grease the chain with special chain grease, and don’t forget to 

mount the protection over chain and sprockets.

Allways use inlet silencer to lower the noice and protect the en-

gine from dirt.

Now let us make the basic setting of the carburettor:

Turn both the fuel needles (marked L for Low rev mixture and H 

for High rev mixture) gently clockwise until you feel that they bot-

tom.

Now open (anti clockwise) the H needle 1 turn and the L needle 1 

turn.

This is the basic setting, and we guarantee that you can run the 

engine with this setting as long as you practice to get used to 

the engine and the kart. You can lower your lap times with some 

tenths of a second if you screw the H needle clockwise (this gives 

leaner fuel mixture) – BUT YOU MUST NEVER CLOSE IT MORE 

THAN TO ½ A TURN OPEN. If you close the H needle, you MUST 

open the L needle to enrich the mixture at low revs,

Let us say L needle will be 2.5 full turns open. The correct set-

ting of the two needles is one of the secrets of the successful kart 

mechanics, but here are some hints:

Look at the sparkplug. It is white, the mixture is too lean. If it is 

black or wet, the mixture is too rich. Correct setting shows a light 

brownish color of the sparkplug electrode.

If the H needle is correctly set, you will notice that the engine goes 

over in 4-stroke just at the end of the longest straight.

If the L needle is correctly set, the engine will respond immediately 

when you push the accelerator after you have had it released (e.g. 

after a sharp bend).