Two stroke carb settings

[extra300s]

Hi there guys.

Not flying microlights just yet but do have a consirn on the two stroke motors these planes use. I have read a bit on the accident forum and the maintance issues. Just wondering how does one properly set you fuel mixtures? On a four stroke engine you get an CO instrument that you clamp to your exhaust and then set the carb to optimum setting. On the two stroke this seems to be very important (and I do'nt think this device could be used on these motors). If the needles on the carb are to lean, the motor over heats and could die, or loose power. To rich again and you stand the chance of carbon fouling the plugs and there again you could sit with a dead stick. Maybe I have it all wrong but this at least is how the 45cc 2 stroke motor on my model plane works. And I have experienced the to lean and to rich setting on this motor - had a dead stick and power los due to above.

This the one thing that bugs me a bit. Hope that someone can explain this to me.

[Morph]

No need to worry

These are very simple motors with very simple carbs. Once set up they tend to run extremely reliably for long periods of time. Don't fiddle, just fly.

You biggest problem fuel wise is to remember to put fuel in, to remember to premix the fuel (if you don't have an oil injection facility, in which case remember to put oil into the reservoir) and to keep your filters clean. The rest is easy

There are basic settings on the carbs, i.e. setting idling, using the right jet size for your altitude, setting your needle jet clips, idle jets etc, are all documented and simple to set. Reading your plugs will reveal if you are running a touch lean or rich. It is not something that suddenly decides to go wrong for no reason.

Once you get into it, and you have additional gauges like EGT's you will use these to finer tune the motor.\, i.e. get a perfect balance of temps between the pistons and learning the right rpm for long descents to avoid heat and lean mixtures.

[Mogas]

Welcome Extra300s
Nice model! Wish I had more playtime to fiddle with mine.
Ditto to what Morph has said.
You have experience adjusting and experimenting with mixtures on your models, same thing on a micro, just easier
IMHO EGT guages are probably the most important guages you can have, fortunately they are very simple and relatively cheap. These will give you a wealth of info regarding the health of your motor which you will soon get to know and as soon as there is an unusual rise in the EGT it should be investigated.
Safe flying
M

[extra300s]

Sounds all good - thanks Morph. Do you fly a trike or something else?

[extra300s]

Hi Mogas

Use to fly at Nelspruit (actually only once ) Still in High School then - Rob Ferreira and there was n onnie the meneer Morrow that allso use to fly there.

Thanks for the info. Don't know if I would fly much either if I get into microlights

Cheers
Karl

[Morph]

912 Bushbaby, currently being rebuilt.

I have only ever flown 3-axis, Skyfox and Challengers

[extra300s]

You doing the rebuild yourself Morph?

[Morph]

built it the first time round myself.

I now don't have the time to rebuild it so I am getting the great Boet Laubcher to rebuild it for me

[extra300s]

Found the rebuild under the projects section. Did it have a light prang there? Looks like it will fly soon again.

[Morph]

slight mishap , lost a front wheel on landing, nothing much ended up trying to taxi inverted.

http://www.microflying.co.za/viewtopic.php?f=16&t=6427

[Ranger]

Whaaaaaaaaaa hahahahahahahahaha heheheheheheeheheh mphmphmphmph Sorry Morph couldn't resist. When are we gonna have some again?

[Byron]

The two strokes used in microlights are not nearly as fiddely as the small model two strokes running on methanol.
Unike the model motors (o.s, supre tigre, 3W, enya etc.) that must have the carbs either richened or leaned out almost every time you start them, the larger petrol two strokes are setup once and thats it.

[Morph]

After Tues night

This weekend

[extra300s]

Who does the engine inspections and maintance/overhaul in the Western Cape?

[Morph]

Tommi Coupe, and a number of other guys in the WCMC club. It's a good idea to join the club, everything you need and lots of very good advice and experience is available. Costs R400 per year, we meet once a month, arrange events, competitions, fly aways. Great fun.