RB Concept engines, Instruction Manual

Page: 12 / 19

2) After the engine has run at idle for 125cc, you should let the
engine cool down before restarting it (be certain that the piston is not
stopped at TDC), and open the main needle for at least ½ turn more than
it was originally set. We now suggest you run the engine on the track so
it will be cooled properly. During this process, be sure the engine does not
make too much RPM (the engine must be making a sound like a four-
stroke engine and you must see fuel coming out of the pipe). If the engine
makes too much RPM, close the throttle immediately and open the main
needle one more turn, and repeat if necessary until the engine suffocates
due to too much fuel, and in this way you will be sure there is enough
lubrication and the RPM does not go too high. Run the engine like this for
at least 375cc of fuel, and avoid extended periods of full throttle running.
3) After this you can start closing the main needle so the engine
makes more RPM but still makes a four-stroke sound and smokes a lot,
this for at least another 375cc of fuel, and avoid extended periods of full
throttle running.
4) After this you can close the main needle further until you reach
about 80% of the engines performance (more RPM but still smoking), this
for 250cc of fuel.
5) After this you can really tune the engine to go to 90% or 95%
of its power but take care so that you do not overheat the engine causing
it to loose power, if this happens stop immediately and open the main
needle 1/4 of a turn.
Attention: During the running-in periode the engine must always have
a good and constant idle and have plenty of smoke and excessive
fuel coming out of the stinger.
6) Carburetor settings
To be able to adjust the carburetor of a nitro engine correctly, you need
patience and must try and understand how this works. Sometimes nitro
engines are difficult to set, and if you have difficulties, then we suggest
you ask your LHS (Local Hobby Shop) or Dealer where you have purchased
the engine to help you in this matter.
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