ZDZ40 plug spacing??
 

My ZDZ40 is a b.... to start.
It is mounted inverted and the standard method never worked (choke, flip till bang, open choke and flip). Always ended up flooded.
I recently started to use a starter with no priming, it worked a couple times but now the engine turns forever with just a short bang in the beginnig.
Everything looks fine and my concern now is the plug spacing. I reduced it a little bit (now .25) and it started after a couple flips by hand.

What is the correct spacing?
Thanks

Ben

ZDZ40 plug spacing??
 

Try .20. .25 is a bit on the too wide side. Check also the spacing between the magnet and the sensor. Too wide here will give the symptoms you have.

ZDZ40 plug spacing??
 

OK, I did some research and found that the Falkon instructions on the homeland ZDZ website recommend a 0.35mm spacing (equivalent to 14 mills)

***
Falkon ignition installation
1. Before installing the ignition, read the instructions carefully.
2. Make sure that batteries cannot be connected while installing the ignition.
3. When placing the ignition into the model, choose the position preventing mechanical damage of electric unit or cables during operation. The ignition and all parts that are connected to it ( engine including the batteries and cables must be placed as far as possible ( at least 25 cm) from the radio set and all it's parts ( batteries, locator, cables etc.) Fix cables well whenever they lead through the model. The guarantee doesn't include mechanical damage of ignition or cables.
4. Distance between electrodes on spak plug UR 17 must be 0.35 mm
***

At the same time, the Vlach instructions that I received with the engine specify a 0.7mm spacing (or 28 mills)

What to believe?

ZDZ40 plug spacing??
 

If it has the small plug set it at.015, If it has the large plug use .020

Gap
 

1 mm is .03937", SO, .7mm is .027559" or .028 (14mm plug)
.35mm is .0137795" or .014....A few thousandths one way or the other makes no difference at all..Under .010 on the 10mm CM6 won't fire well..............

ZDZ40 plug spacing??
 

If u have the Falkon ignition, plug gap is .35mm, if u have the Vlach ignition, gap is .7mm.

Make sure the hall sensor is set up right, If your timing is too retarded it will be hard to start.T he Falkon should measure 7mm from the centre of the sensor to the centre of the magnet with the piston at TDC.

The Vlach set up is not the same, don't know what the spec is.

Mike

ZDZ40 plug spacing??
 

Funny you mentioned the sensor position. When I received my 40 the screws were lose on the sensor bracket and it would flop from side to side. I thought no big deal I'll set it up according to the manual. Piston at TDC, 7mm from center of magnet on hub to center of sensor. With it setup like this it was hard to start, ran very poor, and got hot. I used a electronic infra thermometer and the temp ranged from 340 to 360. Way too hot! I stopped running the engine and called rcs. Mike Dooley told me don't go by that, it's way to retarded, he suggested going from the crankcase web center to the center of the sensor bracket 7mm. Also if you remove the sensor bracket at this location there is a mark on the hub right where the center of the brack sat. This places the sensor at the complete opposite range of adjustment then it was using the other method supplied. Strange. But now the 40 starts easier and temps are from 190 to 220. It still runs poor but not as bad. I will call him again tomorrow. Just thought this info might help someone.

Dave

zdz 40
 

Hi Dave,

when u say your zdz 40 still runs "poor" can u clarify for me, exactly what's it doing?

Thanks

Mike

ZDZ40 plug spacing??
 

Hi Mike,

Boy this could get lengthy

First off the idle is rough, it can be leaned out to a smooth idle but then transition is null. The midrange is way too rich or seems that way. It can be leaned to be smooth but the idle is too lean and it will increase rpm and die in short order. We tried adjusting the low needle in very small amounts with no luck. Just cant seem to find a happy medium. In order to get a rapid transition the low end must be richened and then the midrange is horribly rich. Making any since here? I can get a smooth idle with no transition or good transition with overly rich idle and midrange.
Full throttle is fine, it will hold an rpm and responds well to needle adjustments. Only thing is going from full to idle quickly it will die if not "goosed". That part is most annoying. I am using yamalube (not the R-1 synthetic) mixed at 40:1 and have 9 16 oz tanks through it. I know its not fully broken in yet but surely things must be better. I know it sounds like I'm too rich here or too lean there but we just cant find middle ground.
At any rate I'm open to any suggestions, maybe theres something that has been over looked.

Dave

ZDZ40 plug spacing??
 

That 7mm adjustment has me puzzled. You basically adjust something (a distance) while expecting something else (a spark). If the sensor is slightly rotated in the bracket, it will read the field from the magnet differently.

The best way is to find the TDC with your caliper, then increase that distance by a fly's hair and adjust the sensor position so you have a spark when the piston hits the caliper when you rotate the prop. With this you look at the direct end-result and not a distance. This method is described on the Flakon website by the way.

Ben

zdz
 

Ben, I agree with your ignition set up method, when u set up like this u should find that 7mm ends up being the distance from the sensor to magnet centres.

Dave, what u have going on there is definitly not normal for this engine, I would give Mike Dooley a call and see what he suggests, sorry I can't be of any more help than that.

Mike