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I had the first start of the 912 on my KFIII project today! Everything looks pretty good but I have a miss on the right ignition that I have to trouble shoot. Any suggestionwhere to start ?
Also I need to get another wrap in my bungee. What's the best way to jack it up to do this. When I orignally installed the bungees the engine wasnt mounted and I just rolled it upside down. Wish I'd put in an extra wrap then.
thanks,
EG
EG,
What I have always done is make a saw horse type thing with a few extra gussets for strength an inch or so taller than the space between ground and the brackets at the lift strut attachment. While I lift the tail, my wife positions the saw horse under the fuselage and by pushing down the handle at the tail, you can lift the wheels off the ground. Strap on a weight or attach the strap to a tiedown and it will hold the tail down.
Lowell
I have a set of "tripod" wing jacks that I got from Airdale. They lift on the wing at the attachment point of the lift struts.
They were designed, with the matching tail jack, for the installation of floats, so they have plenty of travel.
EG, I'll make an assumption that your carbs are fairly in sync with each other and that you don't have a choke sticking partly open during operation of the 912 , obviously both fuel air issues and not electrical.Quote:
I had the first start of the 912 on my KFIII project today! Everything looks pretty good but I have a miss on the right ignition that I have to trouble shoot. Any suggestionwhere to start ?
A possible and probable cause:
Look for an intermittent ground on one of your ignition modules. One black ground wire comes out the side of each module.Very common problem where the copper wire strands break inside insulation. The modules have to be grounded to operate. When the engine vibrates it can cause intermittent continuity on the ground circuit of that module causing the roughness. Of course this is not obvious during a visual inspection of your wiring.
How to discover the wire break? Get two small stick pins. Put one pin through the insulation touching the inside copper strands very near the ignition module in question. Poke another small pin into the same ground wire a ways away from the module, again making contact with the copper strands inside the insulation. Attach a continuity tester to the pins and check for good continuity between the two pins. Wiggle the wire between the two pins to simulate the engine running and shaking. If you get a break in continuity on the tester you know there is a problem somewhere between the two stick pins. Keep the pin closest to the module in place and begin working your way towards the module with the other pin. You're trying to isolate the location of the wire break inside the insulation. Usually the break is far enough from the module to splice in a new piece of wire and fix the break.
You don't need to have the engine running or the ignition on to check the grounds on the modules. In almost every case the ignition module is fine. They very seldom fail. Check the ground wire first before spending lots of money on a new ignition module.
Why does the ground wire fail? My guess has always been that the vibrations from the engine running, starting ,stopping cause this failure due to the modules being mounted on the engine side of the motor mount and not on the firewall side of the mount. The ignition modules vibrate along with the engine. The wires flex constantly and eventually fail. I had this problem on my Model 3 years ago and it drove me nuts for a month trying to figure out the cause. Finally we discovered that broken ground wire. I've mounted my ignition modules on the firewall side of the engine mount. Also make sure the wires are well secured so they don't bounce around from air flow inside the cowling during flight operations.
Good luck on the hunt for the miss. Keep us posted on the results.
Do you by any chance have any pictures showing the ignition modules mounted on the firewall, and how you ran the wires? One of the next things I have to work on with my Kitfox 4, will be installing the engine. (912) Thanks, Jim Chuk.
not too good of a picture of the ignition units but you might be able to get an idea of where i located them . made up brackets and mounted them to the engine mount with adel camps . need to insure the ignition units have sufficient grounds
Jim, Here is another look at ignition modules secured on a IV.Quote:
Originally Posted by avidflyer
http://www.azshowersolutions.com/Engine9.html
There are many ways to secure them...best to keep it a bit aft to evade excessive vibration.
It is really tight with the ing. modules and the cooling spider. I had a struggle fitting it all. Call Murel Williams, he makes a neat mount for the ingition boxes that goes on the oil tank, it helped alot.
EG