Hi,
Nice results. Can you specify "jumping around" a bit more ?
As the bike needs richer mixture when accelerating, it is logical that when increasing rpm under load at WOT, the mixture gets leaner. This is the reason why the mixture need to be on the rich side, to accelerate and to keep the engine in one piece.
Jensen
Dynojet A/F MeterThose are my thoughts also on next steps to try. I'm guessing it would be better to target the A/F for main at highest RPM, rather than lower or medium under wot. As I slowly transition from wot to 3/4, I can feel a slight increase in power. Before I change anything else, I think I'll try with air cleaner removed and see what effect that has. On returning home I noticed the meter needle froze at 11.5, so I thought I had a wiring problem. But after turning it off and back on it seems to be working now? 66 dream, 78 cb750k, 02fz1, 09 wing
I wasn't able to spend as much time monitoring at low throttle as I needed, and decided to concentrate on main circuit first. Since the reading was changing as I was trying to keep up in traffic, and I need to move the TPS so the lower settings are more readable from the seat. I was amazed again at how much "normal" operation up to 50 MPH was at 1/4 throttle or less, and this is the area I need most to smooth out. Also, I don't have a good feel yet for how much lag time there is between throttle changes and resulting meter changes. 66 dream, 78 cb750k, 02fz1, 09 wing
Jensen, yes it needs to be richer to accelerate but what you are seeing here IMHO is a classic fuel slope issue. As revs rise, the mixture changes and that's where the air jet comes in. Larger air jet leans out the top end more than it leans out the lower to mid ranges.
A smaller air jet would tilt the fuel slope to get better fueling all the way through the range, but at the moment the A:F is too rich almost everywhere so better to start with the right bottom end and then get the main jet right for top revs and work back through the compromises down the rev and throttle range. The really important point is that much of our riding is done at small throttle openings. Get that right and the bike becomes much nicer to ride and that's what it's all about. Ran a few errands on the Dream yesterday, but no real testing time.
It was 20 degrees cooler (60F vs 80F) than my last run, and I noticed the readings seemed to run a point or so leaner throughout. Opening the air screw to 2 full turns out got my idle A/F above 12, but going any more than 2 didn't seem to lean it any additional. I'm running a 35 pilot, which I think is the leanest available, and 120 main. All jets, and needle are OEM Keihin. Needle is one notch richer than middle, which probably needs to change. More later..... 66 dream, 78 cb750k, 02fz1, 09 wing
Got a chance for one more test run before fiddling with any changes.
This time I took the time to stop and write down the results before I got them confused, or forgot what they were! Conditions: Elevation.....2500' Temp..............75 F Main..............120 Slow...............35 Needle..............2 from bottom (if my memory is right) Motor ...............stock (16,000 miles showing) Air Cleaner........long pod (extended back from carb) Exhaust.............Apex style (with puncture enhanced baffles) Plugs.................D6's Air screw...........2 1/2 out Rider weight.......220# Results: Throttle position.............AFR (min-max) Idle........................................11.5-12.0..(air screw 1 1/2- 2 1/2) 1/8.........................................12.5-14.0 1/4.........................................12.5-13.0 1/2.........................................11.0-12.6 3/4.........................................12.2-13.5 WOT.......................................11.5-12.5 All readings were under load (except idle) All readings increased in A/F ratio as the RPM increased. Was able to reach 75mph on level road sitting upright. Pulled the plugs after the 45 mile run (not chopped):
66 dream, 78 cb750k, 02fz1, 09 wing
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