Hi all, After taking my new extra to the field on saturday we have had problems with the ignition/plugs on my 3W 70 twin. It would only run on one cylinder, found out the problem to be a worn spark plug. But when we took the plugs off and tested them in the caps and turn the prop over it took a good throw of the prop to get a spark.?? I could'nt get a spark by just slowly passing the magnet past the sensor. So something isn't right.

Also i think my sensor/timing is out, as it is now a bugger to start. How can i tell where the sensor should be??

Thanks

Andrew

I believe I recall reading something either here or somewhere else where you will NOT see much of a spark that way. Change your plug and then see how the engine runs. At the same time see what made the other plug fail. Could have been just at the end of its life or fouled by some other means. What was the color of the failed plug?

........Mark

The old plug end was black.... so maybe it was worn out. Will try the new plugs later today when i go down to the field. I also have now heard that they only fire when you give them a good throw...something to do with safety, so they don't get knocked and fire!!

Thanks for your help

Andrew

Andrew, black colored plugs usually mean your running too rich of a mixture so try to lean it out (low end, high end or both) once you get the new plugs in. A good setting gives you a plug that looks light brownish in color. If it's white, it'd too lean.

Have fun.........Mark

Hi Andrewr ,
I have just bought a 3w 70 twin that hasnt been run for a while and whilst I get 'sparks' when the plugs are out it dosent wanna start either - can you give me any settings for anything cocerning this engine as I have none,
cheers

With the DA or 3W ignitions, you only get spark if the magnet is moving rapidly passed the pickup. The pickup is a coil, not a Hall sensor. A Hall sensor will give a spark at zero rpm.

The timing is set when the dash mark on the hub is aligned with the dash mark on the crankcase. This puts the piston at Top Dead Center. At this point the sensor is moved so that the magnet on the hub is aligned right between the "3" and the "W" stamped on top of the sensor. Before you do this, take a felt pen marker and straight edge, and draw a line through the center of the magnet onto the hub. You then use this line as a reference, since the magnet will be hidden under the sensor.