Still trying to wrap my head around jetting and what the symptoms of those changes feel and sound like. I believe I have jetting dialed in correctly and plug always looks good after running at different throttle positions. There are no flat spots or bogging. I have been riding on a smaller highway 2 mile connector between the main streets I normally ride on, to get used to highway speeds and to see if I am comfortable with the top speeds of my scooter in light traffic on a highway (which I am not). What I've noticed on my stella is that when I am at WOT and max out on speed (50-55mph) in 4th gear on this stretch of highway, my scooter starts to slowly pulse higher rpm lower rpm on about a 1 second pulse up/down cycle but rear wheel never locks up. I don't believe it is a flat spot or bogging from incorrect jetting. Its like the scooter is hitting a wall of max power and when it hits that wall, it goes back down a bit then goes back up and hits it again. This is on about 2 mile stretch of less populated highway, WOT for the whole length. If I back off WOT slightly it stops pulsing RPM and holds steady.
I have temp and rpm gauges on. Scoot never gets over 225F at WOT, granted it is only like 45-50F out. RPMs when in neutral and in 3rd gear can rev up to 6500, but at WOT under load in 4th gear max out around 5500. Everything is stock on the scoot except sip road xl and boyesen reeds.
I don't think this is a soft seize as the rear wheel never locks up and the bike engine doesn't seem to be locking up at all. I want to think that it is fuel starvation at WOT? I replaced the LML stock petcock with a PX petcock from scooterworks, which seems to not have reserve setting, just off and on. Also replaced the fuel line recently. Carb is stock 20/20.