Oddly enough, going down to 135 mj on a 1 degree more retarded ignition setup, I thought it would be more peaky and yet it felt alot like the 138 at 24 degrees. The main difference was everything is cleaner throughout, but the spluttering and bogging changed slightly. Overall I think it is very close to dialed in as quick accelerating from stop up the gears it barely splutters, except that now it feels like there is a slight dead bogging spot at full throttle during mid rpms until it gets to very high rpm which it finally clears up. low rpm doesn't have any bogging anymore but holding mid throttle has spluttering that doesn't seem to affect the acceleration or deceleration much. Plug is looking much closer to correct starting to turn brown now, but still looks a little rich.
I might even say that 135 MJ on this 1 degree more retarded timing is now too rich and could possibly go down to 132 MJ (125 measured).
As far as temps, going from 24 to 23 seems to have settled the temps more stable they really are solid around 220-250 at casual city driving with lots of lights. Holding for longer at WOT it will climb to 275-300. It might hold at 300 for long wot runs or it might just slowly climb up a little above 300F, not sure. It feels like it is really close in terms of solid cruising temps. Even with the drastically leaner idle jet from my initial starting jet size the idle settles really fast and temps go down at red lights. Its amazing how this thing can take a much smaller idle jet now despite being more displacement and larger carb than when it was stock.
The finish line feels visible in the distance finally! Now its just a matter of cleaning up the slight spluttering at mid throttle and the little bit of bogging at WOT. I am also wondering if Jack is right and maybe 1 more degree retarded timing will really solidify the stable temps. After reviewing the SIP vape timing diagram again, I realize that 23 on the T mark is actually 24 at 4000 rpm and 17 at 8000 rpm so it might still have a little more room to go down to 22 on the T mark which would be 23 at 4000 rpm and 16 at 8000 rpm. I also have a few smaller idle jets he suggested on order waiting to ship and try those out to see if those would clear up the low end splutter. 45/160 and 48/160 idle jets.
Audio files of two parts of my run. you can hear now if i hold mid to 3/4 throttle at cruising speed for long it does not sound spluttery much anymore and just sounds like a consistent healthy engine.
plug photos below all on 45/140 idle. 2.5 full turns air mix. 120/be3/135MJ (128 measured).