ok I need some help, yes again..

I have an SPE 43, it only has about 3/4 of a gallon thru it and it is running pretty rough. When flipping the prop to start, it will KICK back almost everytime. Is there a way to lesson this or to get it to stop?

Adjust the timing back a lil bit.

Alta has it right .. your ignition is firing too "early" as the piston is still coming up. Is it a magneto ignition, or electronic?

To work correctly, a gas engine has to have ignition timing that advances with RPM. Let me try to explain ... At low RPM, e.g. when starting, you want the spark to fire very close to the point where the piston is at "top dead center" (TDC). But as the engine speeds up, you need to have the spark go off before the piston gets to top dead center .. typically 26-28 degrees (almost 10% of the arc of a circle!), this is due to the fact that the combustion of the gas/air mix is not instantaneous, and this advanced timing lets the explosion of the fuel/air fully develop as the piston gets to the top, this gives maximum power.

If the ignition spark timing is advanced when starting, it will fire on the upswing of the piston, resulting in the kickback.

In a magneto engine, the designer compromises on an advance (the experts here can tell you how much) that is set a little before TDC .. so it is not too hard to start, and develops a reasonable amount of power, but not as much as it could with a more advanced spark timing. It's a compromise... Many magneto engines (e.g. the Zenoahs) use a spring starter to make this more user friendly.

The electronic ignition units work by having the spark advanced just a few degrees at low RPM, and smoothly advance to 26 or 28 degrees at top RPM, giving the best of both worlds. But they can malfunction, and advance the timing at low RPM and you'll get kickback. I have heard that some brands of ignition do this when the battery is low... or the unit might be defective. Or the sensor might be placed at the wrong point .. they often can slide back and forth a little for tweaking.

Hope this is helpful... and gives you a place to start troubleshooting.

Dave

(edit .. looked up the SPE motor .. it's electronic ignition)

ww2birds

Thanks fo the advice, I will see if one of the club members can help me with this..

Thanks again

The SPE comes with the Melody electronic ignition.

Wingspam , In your first post you described the engine as running pretty rough. Does the engine actually run rough or does it just kick when trying to start it ? If the engine runs normaly but kicks back when starting I would try enrichening the low needle by an 1/8 turn before meddling with the timing. A lean low end can cause kickback.

You should see the ignition pickup (sensor) attatched to the engine just behind the prop hub. Pull the engine over till it's at TDC. Now you see the magnet. Loosen the screws that hold the sensor and slide it a little ways towards the magnet. That will reduce timing.
There are two types of ignition units. One needs to be about 5mm+- center of magnet to center of sensor. The other type like CH and rcxl are adjusted to about 28*.
CH website has instructions for setting timing. http://www.ch-ignitions.com/MENU.html

Last week I had problems with a SPE 43 that only had 10 lbs of thrust...[]
After adjusting needles for HOURS I finally noticed that the HALL was NEVER tightned and
had slipped all the way to one side...
Now getting 17 to 18... Still missing a small amount at the top but I think it may be
the Melody ignition...

ANYONE: Will an RCEL ignition work with the SPE Hall switch

No it will not, the RcExl ignition comes with it's own sensor and sensor housing. I've put them on the SPE's and they work great.

Anyone know why the electronic ignition has to be set at between 28-32 degrees BTDC when setting it by turning the prop? You would think tha when turning the prop by hand (at a slow rpm) the electronics would be sparking it for an idle rpm which would be close to TDC. At high rpm the spark ignites at 28-32 degrees right?

The ignition module senses the amount of time the magnet spends under the sensor, it remains at full advance unless the time the magnet spends under the sensor is less than it would at an RPM of about 500. When timing the engine you are turning it over slowly by hand to find the exact moment that it sparks and read the total advance on the degree wheel.