I have eventually managed to get my motor done on my MC18SP, popped it in, connected everything and started her up. It started on the second kick. Now that I have put a couple of km's on it, there is a little problem that is irritating me. When I start it up from cold, with no choke at all, it would start first kick, but it would idle at about 4000rpm for about a minute and then settles down to normal levels (+/- 1300rpm). If I pull the choke in this minute or so of high idling, the revs/idle actually drop to normal levels as well. My first thought was that this means that the air screw settings are incorrect, I had it set up initially as per the diagram in the workshop section on this site, 2 and 1/8 turns out on bog standard jetting and pipes... I have tested every 1/8 increment from 1.5 turns all the way up to 3.5 turns. Same result. I have re-cleaned the carbs checking that all jets and jet sizes are within spec, checked that all the air channels in the carbs are open and clean, checked all my air correction piping, the air correction solenoids, inlet rubbers, expansion tanks etc for leaks and correct operation, all fine. RC-Valves are set up correctly and working properly, TPS tests fine on multimeter.

When the engine is warmed up it runs well, idles fine and runs strong all the way to about 11000rpm and then slightly wanes off on its way to 12000rpm. Its just this high idling on cold starup issue, any ideas anyone?

Jacques.


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I love the smell of two-stroke in the mornings!