rng3
"There is no replacement for displacement"
- Joined
- May 8, 2018
- Messages
- 420
- Location
- Chester county, West of Philadelpha
- Ride
- Rocket 3 roadster 2017
Been researching the timing tables. Downloaded the tables the bike was delivered with and find that the advance is delayed a bit or different for 1st and 2nd gear than the rest. Does anyone know why?
It has been recommended to copy the upper gears table to the lower, which I have done as that gets more timing in sooner.
Also looking at different tunes they also vary. The tune Penner graciously contributed seems to use a different strategy. I wonder if Penner and others in the know could expand on the reasoning for the setups they are using.
In old school the theory was to determine the best timing for power say 38 deg. The timing at idle needed to be relativity low say 8 deg. and then the timing was increased by an advance curve as engine rpm increased. The timing was "all in" at max by say 2,500 rpm and stayed there to red line under full throttle. A vacuum advance if installed allowed the timing to advance even further say another 8 degrees under low load conditions for better fuel mileage. So in normal operation the timing was determined by rpm and load. Under heavy load the timing was retarded to avoid knocking.
The tables do something similar but with much greater control and are still based on load and rpm. The tables probably now also take into consideration exhaust emissions. Too much timing can increase one type exhaust emission and too little timing can increase a different exhaust emission. It also effects exhaust temperature.
Considering the low compression ratio of the rocket and with using premium gas knocking should not be much of a problem at realistic timing settings.
As a side note long ago with carbs we would sometimes use a vacuum gauge to set the initial timing at idle. Warm the engine up and adjust the timing for the highest vacuum possible.
Thanks,
Rick
It has been recommended to copy the upper gears table to the lower, which I have done as that gets more timing in sooner.
Also looking at different tunes they also vary. The tune Penner graciously contributed seems to use a different strategy. I wonder if Penner and others in the know could expand on the reasoning for the setups they are using.
In old school the theory was to determine the best timing for power say 38 deg. The timing at idle needed to be relativity low say 8 deg. and then the timing was increased by an advance curve as engine rpm increased. The timing was "all in" at max by say 2,500 rpm and stayed there to red line under full throttle. A vacuum advance if installed allowed the timing to advance even further say another 8 degrees under low load conditions for better fuel mileage. So in normal operation the timing was determined by rpm and load. Under heavy load the timing was retarded to avoid knocking.
The tables do something similar but with much greater control and are still based on load and rpm. The tables probably now also take into consideration exhaust emissions. Too much timing can increase one type exhaust emission and too little timing can increase a different exhaust emission. It also effects exhaust temperature.
Considering the low compression ratio of the rocket and with using premium gas knocking should not be much of a problem at realistic timing settings.
As a side note long ago with carbs we would sometimes use a vacuum gauge to set the initial timing at idle. Warm the engine up and adjust the timing for the highest vacuum possible.
Thanks,
Rick