Originally Posted by AeroFinn
I'v been thinking about this route, too.
However, one thing that is confusing is the Zama in conjunction with the FG 20 seems to give about 8100-8300rpm with 16X6 evolution prop as peak according to Adrian's experiments . The original Saito carb seems to perform better what comes to max power output: about 8500-8800rpm with 16x6 apc or equivalent prop according to various tach readings reported?
Only when tach readings are done back to back W/the same prop on the same day at the same location, can #s be used as a comparison. When making difinitive power gain tests I always do that. I have seen 200 RPM varaince W/my FA300TTDP CDI when I broke the original 22X8 Zinger & replaced it W/anoter 22X8 Zinger.
Adrian seldom experiments W/ignition timing beyond the 28* initial setting. A bit more advance might also boost power output. It certainly does when burning methanol W/CDI.
Adrian's tests could have been done on a day W/high humidity or windy conditions.
I also suspect that some manifold work to blend the bore of the ZAMA carb to the manifold diameter would help.
On my FA180HC CDI engine I gained .45HP when I modified an FA150 intake manifold to the ID of the FA220 Big Bore carb on the updraft portion & opened up the horizontal portion that joins the head to the size of the 180 intake port. I doubt that I would have seen that much gain from just bolting the big 12mm 220 Big Bore catb onto the standard 11mm bore FA180 intake manifold.
Once CDI is introduced into the equasion, there is lots of room for various tweeks to maximize power output.
That's why I convert all of my Saitos to CDI even though I still burn methanol feul. The ignition timing can be adjusted to take advantage of the various tuning needs that arrise.
Besides, which is better, an engine that makes 8300 RPM of dependable power, or an engine that might make 300 RPM more that is unreliable?