Hello all!

I fitted up a spark plug and CDI on a glow ignition engine (Super Tigre 3000) for the fun of it and am experimenting with GLOW fuel 0% nitro, 10% Klotz and a dash of Castor, methanol carb (from an ASP 120) and small spark plug. RCExcell ignition and no other engine mods.

Starts up fine and idles nicely at 1750 RPM but when I raise the throttle, lower it and raise it again, it sometimes backfires and quits. Looks like a little smoke blows up the carb as when it does that but not sure. I know this has something to do with timing but what should I do to fix this problem? I fitted up a timing ring with an advance of 30 degrees from top dead center. Should I advance or retard the timing to prevent this from occuring?

Thank you in advance for your expert advice and Happy 2015 to all.

Regards,

Ranga.

Try a little less advance.
It is not going to hurt as to how much so start around 15 to 20 degrees and see what happens then.
Methanol burns more slowly than gasoline.

It's not simply a too-lean idle mixture?

Broke the spinner. Got a new one on order. Will resume tinkering when it arrives and post results.

I would look to the mixture first. 30 degrees advance should be fine. Normally with alcohol, you can run more timing before bad things happen. The fact that it revs the first time makes me think the timing is right. It could be too lean, or it also could be too rich and and it is loading up and when you advance the throttle again, there is too much fuel and it backfires. I would pick a direction and go with it and see what happens.
Has the conversion changed the fuel consumption?

Yes, I agree. However, what ignition are you using? Most of the ignitions sold now have an automatic advance. Actually, "automatic advance" is a misnomer. What they really do is automatically retard.
You set the timing statically at 28 to 30 degrees total, and the igntion retards the ignition at cranking and idle speeds, and then advances it back to the 28/30 degrees that you originally set it at when the engine is at higher rpms.

Anyway, if your timing is indeed correct, then yes, the backfire through the carb can definitely be caused by too lean a idle and/or midrange mixture, especially when opening the throttle rapidly.

AV8TOR

My experience with the YS160DZ engine, by using RCExcell, small spark plug, 0% nitro with 20% castor. I start with a rich mixture with timings of about 15 ~ 20 degrees.
The engine running with alot of smoke first, after setting it was running well with around 26 degrees BTDC (8200 rpm with 18 X 6) , less smoke at hi RPM but little smookie at idle and when opening throttle rapidly.
Every week I flying with this engine in my "old" Carl Goldberg Yak 54.

Regards,
Kartika

Curve from micro advance retard system.