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« on: April 28, 2023, 06:33:02 PM »
I thought I'd run something past you guys (what again!), trying to get my TS125/VM32 jetting fine tuned, I think (?) umm how do I put this into type .... ok I'll start somewhere.....
In neutral, rev the bike up, chop the throttle, rpm's hang up (probably around 1500 rpms?) like too lean (which it is), after aprox 20 seconds the idle comes down to aprox 800 rpm (nice idle), then finally conks-out.
I think, as the rpm is quite highish, with a closed throttle, just after closing the throttle, the engine is drawing fuel from both the pilot/airscrew AND the needle-jet, once the idle rpm can creep down, fuel stops being supplied by the needle-jet and then the pilot/airscrew has sole control.
So, in all my years I have never had a bike with this kind of issue, probably because I am basically starting from scratch, rather than someone else (the manufacturer) doing the hard work. I never considered that the straight section of the needle/needle-jet can be drawing fuel with a closed throttle! I guess only while the rpm is high enough to have air speed to do so.
While confusing myself, I had the pilot jet too rich and the needle-jet to lean, bike revs its tits off above normal idle rpm (lean), conks-out at normal idle rpm range (too rich) ..... all rpm affected, with a closed throttle !
Ok I'll work on my theory tomorrow, hopefully I am correct :-)