by rayjb60 » Wed Feb 01, 2006 4:46 pm
Hi Shannon,
About the lower idle with CDI.
Whats happening is that with the points system, the strength of the spark is a function of the rotor speed......slower speed equal weaker spark to some degree.
I have actually seen the difference with the plugs out and pulling the engine over.
The spark was small and weak.
Once I switched to CDI the spark is as strong at idle as at full speed....again with the plugs off and pulling the engine over like before I got a big strong spark.....it was a huge difference and very easy to see....I wish I'd mpeg'd it so you guys could see what Im talking about.
So since the spark is so energetic at low speed you get a reliable ignition at slower speeds as well when the points version would start to sputter and stop.
Because of that you can simply reduce the low end limit screw and mixture screw to reduce your rpms to what ever you feel comfortable with.
In fact I noticed that when I throttle down to idle for landing approach, the prop acts noticibly like an airbrake and brings you down at a nice descent rate...which I found quite nice since Im used to spoilers on Gliders for landing path control, I simply played the throttle to bring her down exactly where I want.
Nice short landing roll even without brakes, with the lower idle...I think I was getting about 1800 rpm idle if I remember correctly.
CDI means you KNOW your engine will run until the fuel is gone.....even if it is out of tune.....it makes a huge difference.
Case in point: When I first installed the CDI with the old flywheel it was 50 degrees off in the timing and the engine STILL ran....although it had a fierce kick on starting, but still idled fine.
Once I put the new flywheel on that came with it, I gained some top end rpm and it started much more gently.
I cant say enough good about the CDI its probably the single more worthy mod you can perform to improve reliability, safety and stop having to mess with the engine constantly.
A number of us have made the conversion and there is nothing but rave reviews about it.
The main benefits are:
- Very Reliable and lower Idle.
- Easier starting.
- Maybe a hundred RPM more top end.
- NO ignition maintenance required.
- Peace of mind due to reliability....no engine failures due to fouled points
Ray
<H5>Nothing is impossible...Even the word tells you Im-Possible!!!</ H5>