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Right:
It was bogging like this/worse when I had the accelerator pump still attached.
It is popping on sharp close of the throttle = leaner idle than main.
Hesitation like it is bogging from too much fuel when cracking the throttle too fast from low revs.My thoughts to drop the needle was reading about whether it's getting too much fuel too quickly causing the bog, rather than too little fuel. I tried larger main jets and it got worse not better.
The plan was to drop the needle to smooth out the fuel delivery, rather than add more fuel to the problem. Dropping the needle is the only thing I haven't tried yet.
pdlouche
Dropping the needle will lean it out. If you think it’s lean, drop the clip and raise the needle. The little hesitation you describe when you crack the throttle, sounds like a temporary lean bog (that’s the condition the accelerator pumps can cure - they squirt extra gas at that point.)
You can play around with bigger idle jets too as they do have an effect. Going a bit bigger won’t hurt starting / idling.
Plug chops don’t tell you much aside from mixture at WOT. I’ve never tried doing one on a four stroke but if you do, you need a new plug, pop it in and load up the engine in 4/5th gear, flat out, uphill. Cut the engine when you’re flat out and coast to a stop clutch in. Take the plug out and ride home on a spare.
I find it very hard to read the mixture without cutting off the threads but you’re looking for a solid brown ring about 2mm up the base of the ceramic insulator. Black or much higher is rich, less or feint is lean.