If your engine has been coking up when set up using the manual, then it is probable that
1) you haven't set it up according to the manual, (which largely talks about setting the low running jet), or
2) You have a damaged carb, or
3) You are using the wrong fuel / oil mixture, or
4) You are using the wrong type of spark plug for the conditions (too cold)
What settings / plugs are you using, because the manual prameters are about right (ie between 1 to 1.25 turns out on the Main Jet and 1.25 to 1.5 on the slow running jet.)
The bit the manual doesn't cover is setting up the main jet, it just says get the 'best free running speed' as part of setting the Low jet.
When you are on track, with a warm, run-in engine you do a check choke. To do this, on the straight with the throttle wide open, briefly cover the air intakes so that the engine dies. As soon as the engine note drops, take your hand off the intakes and listen to the recovery. If the engine recovers quickly to the same engine note as before the choke, then you were about right.
If the engine note speeds up before going back to the same engine note, then you were too lean.
If the engine note slows before recovering, then you were too rich.
Adjust the carb a fraction (turn out if you were lean, turn in if you were rich) and redo the operation on the next straight (but give the engine time to have got back to 'normal'.
Another method used to adjust the carb for a particular track is to set the engine rich and accelerate down the straight. The engine should start to 'four stroke' somewhere down the straight. (this is the revs at which the engine is trying to go too fast for the rich mixture). Lean off the mixture a tad and you will find the fourstroking occurs further up the straight (ie the engine is hitting higher revs). The Idea is to get the fourstroking to occur right at the end of the straight, where you would be very late braking.
Also remember that a set-up is designed to work with a standard driver and standard track. What suits a skilled driver using high revs for much of the circuit won't be suitable for a novice using very low revs for much of the circuit.
HTH
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Iame leopard fuel mixture settings...... by 'Littlebranch' (06 Jun 2010 @ 9:28)
