Last night I went riding with the new tuning. New tuning is, 50:1 ratio. Needle in leanest position. 68 jet. Speed carb.
It runs drastically different after this change. Instead of starting instantly with no choke, and running well from cold, now it's hard starting cold with no choke. Warm up now takes a long time. After warm up is complete, it idles well. The spark plug looks great. Dark tan/brown. The way it's running now seems a lot more normal than the way it's been running.
After it gets fully warmed up, It runs well. The top end is great.
The bottom end seems maybe a little weak, but it may be normal for a speed carb, and crappy exhaust. What's different about the bottom end compared to before changing the needle position is, now is it's running smooth with no 4 stroking.
I'm pretty sure the gas mileage will go up, but I haven't proved that yet. I was getting about 80 mpg before, cruising about 25. Now I want to see 120 mpg or close to it.
I notice in the above I made a typo. Instead of a 68 jet, I meant to say a 66 jet.
I got to go on a fairly long ride today. Long enough to get a good feel for the way it runs and the fuel mileage. On this ride I got about 124 mpg. That's 50% better mileage than with the 68 jet. I was only getting 80 mpg before. That was cruising mostly between 25, and 30 with not much 30. I think that's the best mileage I've gotten from any of my 80 motors. It's amazing how much difference one jet size can make.
Performance wise it's running great. It has more than 600 miles on now.
Cruising at 30, if I see the traffic light fixing to change, I can gas it, and it accelerates so hard that most of the time I can make the light lol. It pulls good from the bottom to the top.
I passed a couple today, riding their 50cc scooters like I was riding a motorcycle, oops don't let the fuzz know. Made me feel kind of guilty, having that much performance, and them needing a license plate.
I believe this is about all I'm going to do to this motor, so I guess this is about it for this thread.
This is the final summery
36T sprocket
35+ mph. I don't care to find out how much over 35 it will do, but it's been to 37 a couple of times. I doubt it would do 40 though.
50:1 Red Line synthetic
Speed carb
66 jet
Needle clip in second from the top position.
Modified stock muffler. (removed the cat) Still very quiet.
NGK BP6HS spark plug.
124 MPG