Converting A Four
Stroke Glow To CDI Ignition
Recent comments by SrTelemaster150
outlining the virtues of using CDI ignitions on glow four
stroke engines are intriguing. His arguments are that no
nitro is needed, oil content can be reduced and fuel economy
will improve. I'm not a stranger to mixing my own fuel
and less oil means less cost and effort needed with clean
At play as well for me is easy starting as I've a distaste for
starting the large glow 4 strokes,
A few years ago, I bought a NIB YS-120 intending to use
it on the an Akrobat II. After a few weeks effort trying
to break it in on the bench, I gave up on it mostly due to
discovering that the engine required high nitro content to run
reliable, which I deemed beyond reasonable for a sport flyer.
Converting this engine to CDI will be an interesting effort
and one within my scope.
- I've a lathe and the ability to
make a timing ring mount for the pick up magnet
- I've both the methanol and oil
on hand to mix about eight gallons of fuel... enough to
last a long time
- I've an engine that I deem
unusable for glow ignition for sport flying
Needed will be a CDI setup for a 1/4 x 32 plug but they are
readily available and of course can be used for many
applications so the small investment would not be lost if the
project doesn't pan out. And... I've a Saito 182 twin
that would benefit from a similar effort and possibly the
Saito 125 that is currently in use.
I've ordered a CDI ignition to try to make the YS-120
operable... nothing ventured... nothing gained, eh.
Update: The timing ring has been machined and awaits a
magnet. The ignition has been shipped so will be here
soon and the YS is mounted on the engine test bed and a
suitable prop chosen. So... my finger is on the trigger
for testing. The only thing not done so far is to mix
FAI fuel but that will be done after first getting the engine
to run properly with a regular 15% nitro mix in part to make a
comparison between the two fuels.
Update Early April
After installing the ignition, the motor started without major
effort but ran poorly. To
avoid leaning on top end, the HS mixture has to be set at a
point that at mid range the mixture is so rich the engine will
barely run and in fact won't spool up. Leaning will
allow spooling up but then be too lean on top end. The
engine suffered a couple of back fires and quick halts and may
be damaged as it will no longer even start.
I'm throwing the towel in on it. It needs looked at by
an expert and I'm not sure it is worth the trouble. My
conclusion remains as previous and is in line with those of
others, it is too problematic for a sport engine.
I'll likely install the ignition on my Saito 1.25.