My 2 cents worth. I am taking special interest in this discussion since i am about to order a HACman fuel mixture controller for my 912 ULS. I had also installed a HACman on my 582 powered Kitfox which I found to be a great asset. As I recall, one side of the mixture control was plumbed to both the vent tubes on both the Bing carbs and the other side was plumbed to the joint KN air filter. If you happened to land with the HACman valve in the leaned position it would not start. Based on how the HACman leans the Bing carbs, there could be an issue when the vent tubes are vented into the filter, because that is what I believe the HACman does. My 912 has approx. 4" individual vent tubes tucked under the float bowl bail.
Fuel flow and adequate fuel pressure could also be an issue. I fly with a fuel pressure gauge, a back up electric fuel pump and a warning light that comes on when the fuel pressure is below 3 pounds. At idle and low power setting the pressure is around 5 PSI. Sometimes at full power take off the pressure drops slightly below 3 psi in the 2.8 range. I have heard it said that Kitfoxs will run on gravity only from the wings but not at full power.
My 582 was set up to start cold with a primer. Give it a 1/2 primer stroke too much and it would flood the engine. I would suspect that if both vent lines were pouring fuel into the carbs, the results could be significant loss of power. I am please to hear you are well. Herman
TJay I flew with a 80HP Jabiru in my Model 2 for several years but wished I had the added performance of the newer 85HP model. It came with the engine mount and bolted right up to my fuselage. The previous owner had it on a Kitfox on floats with the round cowl and could not get the cylinder head temps cool enough as apparently was an issue for others. The advice from Jabiru West in California ( no longer in business) was to go with the Kitfox specific engine cylinder air ducts and the smooth Cessna style cowl which had to be ordered from Australia. I had no cooling issues with the installation. I would call the Jabiru importer on the East coast and inquire if engine mounts for Kitfox's are still available before making my own. I enjoyed the engine at or near sea level, but it just did not have the climb and high altitude performance that the Rotax 532 had that it replaced because of the short prop. I wish I had tried the HACman altitude leaning device to see if it would perform better over 8000 feet. No gear box chatter, smooth as silk idle and no radiator; whats not to like? My Jabiru did not like to start when cold when the temps got in the 40's. I ended up with a heavy Odyssey 680 and huge #4 battery cables. They say the Jabiru installation is no heavier than a 582 with a C box which may be true, but not in my case with a 532. I was replacing a 532 which has an A gear box and single ignition and the weight gain was 15 pounds just where a Model 1-2 Kitfox does not like added weight. That 15 pounds moved the CG forward but still well within the range. It was nose heavy so I just trimmed it buy reflexing the flaperons to get hands off cruise. THAT WAS A HUGE MISTAKE THAT TOOK ME A YEAR AND A FORUM MEMBER TO FIGURE OUT AND MADE THE KITFOX HANDLE LIKE JUNK AND DANGEROUS TO FLY. EVERYONE PROBABLY KNEW THIS BUT ME; NEVER MAKE MAJOR TRIM CHANGES ON A KITFOX WITH THE FLAPPERONS, MOVE THE BATTERY OR ADD WEIGHT AS NEEDED.
I gladly share several other installation issues you will have, so please call. Herman Pahls Oregon 541 404 6464
Rumor is that the accident was caused by a fuel flow sender installed backwards? Sad about the results but if is true, what did Vans have to do with the installation. An attorney called a while back to sue me because his client was bitten by the dog that resides in a rental property I own. I asked why he did not go after the dogs owner. He said the the dogs owner did not have any money and I probably did since I owned the house. Also, he said I was negligent in allowing a mean dog to live in one of my rentals. I had no idea the renter had a dog let alone mean. I told him he was a vulture, who my insurance company was and we never heard form him again.
I use 29" ABW with Matco brakes on a model 4 Kitfox.
The brakes were poor until I had Matco sleeve the master cylinders from 5/8" to 1/2".
Matco insists that for their brakes to work well, your pedal geometry and master cylinder bore needs to produce 600 psi pressure with reasonable pedal pressure.
Now they work good enough to stand it on the nose.
I was considering adding another caliper as Leni suggested but wanted to avoid the weight and complexity.
This is a necessary subject since many Avid/Fox "fans" have stopped due to fuel flow issues with plenty of fuel on board, including mine.
What is causing the fuel flow issues if the fuel lines and filters are not clogged or pinched and the fuel pump is working.
Seems like only "air locks", venting or asking fuel to flow up hill would cause the engine outs.
I wish some engineer would chime in and give us the bottom line.
So what can we learn from high wing "factory airplanes" that seem to seldom have fuel flow issues except due to operator error?
As far as I know factory airplanes do not have header tanks, so why do our Avids/Fox's?
Also, many high wing factory airplanes depend solely on gravity (no fuel pumps) since the carbs are the lowest point on the engine.
Seems like on all high wing airplanes, when that tank gets to a certain level air will enter the fuel lines depending on the angle of banking.
Why do factory airplanes seem to not have air lock problems?
If they do not have header tanks, I assume they do not have dedicated vent lines that we have discussed here.
On the Pacer I flew for years, you were not to take off and land on the right tank if the fuel level in that tank was below a certain level.
This was due to the right side fuel lines having to go up hill to reach the left side fuel valve as I understood the issue.
Most rear header tank Avids/Fox's have the Pacer right side fuel flow scenario on both sides, where the fuel has to flow up hill before it gets to the fuel pump.
Apparently some Avids and Fox's have front header tanks which makes more sense to me than a rear header if the the fuel lines are routed forward from the tanks to possibly gravity feed the fuel pumps on 582/912's
The problem I see with small forward header tanks is that these airplanes could possibly climb at an angle that would starve the header.
Do Cessna's risk fuel starvation from long steep climbs and they do not have header tanks?
A forward header tank may cause packaging problems but my model 2 Kitfox has an 8 gallon header tank that the wing tank feeds.
Since I am not smart enough to know one way or another, I have no choice but to follow the Kitfox factory recommendations of venting the rear located header tank to the top of the right side tank since that tank comes tapped for a fitting.
As was mentioned in an earlier post, the key to preventing "air locks" seems to be fuel lines that travel continually upwards from the header to the wing tanks to prevent air from getting trapped and stopping flow.
I have been flying tail draggers for 35 years so I am not sure if I will be any help since I cannot remember what is was like in the beginning.
I am not an instructor so I hope others will correct me if I am wrong or giving bad advice.
Brakes are my only ground directional control since my tail wheel is free swiveling and not connected to the rudder cables.
I am not suggesting disconnecting your tail wheel but using this as an example of how I control my direction until the rudder becomes effective.
Assume you are taking off in a tri gear Kitfox that does not have nose gear steering like a Cessna 150 has.
Until the rudder becomes effective you have no choice but to use the brakes for directional control to counter P factor, wind,....
I cannot emphasis how important your brakes are.
Your brakes are the only thing that will save you from a ground loop if a serious cross wind gust hits you at the speed that you are transitioning from tail wheel to rudder control.
In my opinion you do not need to raise the tail first to take off, but I do most of the time for better visibility and to save my tail wheel from rocks and holes.
Doing a 3 point take off will save you the step of raising the tail but it can be risky if you do not neutralize the elevator before taking off.
I adjust my brake pedals so that they respond immediately to my inputs but also so I am not inadvertently dragging the brakes from normal rudder inputs.
You also may be raising the tail too soon and the rudder is not yet effective.
I wish you well and it will be well worth effort when you get your "shirt cut".
How heavy will the complete Franklin installed weigh be in comparison to the Jabiru that powered that airplane.
That airplane previously was powered by a 582 with a E gearbox which places the starter on the gearbox.
I have flown a model 2 Kitfox for 19 years with both a Rotax 582 and a Jabiru 2200.
The added 20 pounds of the Jabiru over the 582 needed to be balanced with weight in the tail to maintain the flight characteristics of my Kitfox even though the C of G was in the envelope
The Avid my not be as weight and balance sensitive as my Kitfox.
Kitfox's and possibly Avids fly best with the CG near the rear of the envelope.
Is this the time to confess regarding when the fan stops.
37 years flying Lycoming and Continentals; no dead stick landings.
13 years flying Rotax 532 converted to snowmobile ignition; no dead stick landings.
3 years flying Rotax 582; no dead stick landings and still flying the engine.
2 years flying Jabiru 80HP; one successful dead stick landing.
6 months flying Rotax 912ULS; one successful dead stick landing and still flying the engine
The Jabiru would not restart while I was a glider but started right up an hour later after the authorities made their reports.
I had just circled down from 9000 feet to sea level at idle with some occasional bursts of throttle to make sure it was still running well and it quit when I leveled out to enter the traffic pattern.
I either had carb ice or a fuel tank venting problem.
I changed the tank venting and flew it 2 years but never descended for any length of time at idle after that.
I got rid of the engine because it would only climb to 9000 feet but otherwise enjoyed all the simplicity of the Jabiru that John M. referred to.
It would have performed much better at altitude if it were the newer 85HP version like John M. had.
The 912ULS refused to restart even with plenty of fuel in the left tank.
I found out that a Model 4 Kitfox is a decent glider.
Turns out the 5/16" Tygon tubing that came with the Kitfox I had recently purchased had collapsed where it gets flexed the most when the wings are folded (it was not pinched between the wing and fuselage butt ribs) .
I feel that even new 5/16" tygon tubing has too thin of wall thickness and easily collapses when bent.
I replaced it with heavy wall 5/16" rubber fuel line from Napa that you can almost tie it in a knot and it will resist collapsing.
I suggest you test the fuel line you use for how much it will bend before it starts to collapse.
I am tempted to remove some of the covering material and some rib material on my butt rib so I can monitor all of the wing tank fuel line and could have reached up and prevented my dead stick landing by pinching the tygon so it would flow fuel.
I appreciate Doug bringing up the subject and hope that my experiences can prevent a possible tragedy.
We had an Avid go down here a year ago due to fuel tank venting issues and it will never fly again so I feel lucky and blessed with my 2 dead sticks.
I did what FoxDB suggested and agree with modifying off the shelf products versus starting from scratch unless using the lathe is the motive.
I needed more powerful brakes for 29" bushwheels than the original Kitfox brakes had to offer.
I took the Matco A3A axles which are 1-1/4" OD and drilled them out with a 3/4" drill bit on a lathe.
Then slid the bored out axles over the 3/4" Kitfox axle (this axle does not have a flange for the caliper bracket) and welded the Matco supplied plate to the gear leg.
I did the welding with the gear leg still attached to the airframe and it only took minutes to do.
The 3/4 axles are still supporting the weight of the airplane and the welded on plates serve as anti rotation and a place to bolt the bored out axle and caliper bracket to.
I also fly a model 2 that has the Kitfox supplied brakes where the caliper bolts to the wheel.
Removing that wheel requires unbolting the caliper from the wheel and removing the bearing adjustment nut to remove the wheel and hub.
These wheels are not readily available since they require the welded on lugs to bolt the caliper to.
My model 4 has been converted to newer style Matco brakes where the rotor is bolted to the hub.
Removing that wheel only requires removing 3 nuts and does not involve the brakes or bearings.
Matco wheels are readily available in several diameters and I use the 6" wheels for Bushwheels and the 8" for the Nanco's and only takes minutes to change depending on the mission.
This is the same brake system that is used on the Just Highlanders.
I thought Lithium Iron's were safe and Lithium Ion's were the bad boys.
To hear that the Earth X is Iron technology makes me no longer trust my Aero Voltz which supposively is Iron technology or am I over reacting?
What safe batteries are recommended to start the Rotax 912uls (100 hp) ?
I just installed the Matco 1/2" bore MC's and what a night and day difference in brake performance over the 5/8 bore with 29" tall tires.
Before the brakes would only hold 3000 rpm and now they hold full throttle static (5400 rpm) with a 912S (100 hp)
I am sure Matco will sell the forked ends (clevis) separate since I needed the longer ones to get my brake pedals forward of the rudder pedals.
I ordered from Matco the 1/2 bore MC's.
You are correct about the the more pedal travel required when using smaller bore Master cylinders and in my case it is a non issue and the only way I can get the brake performance I need for 29" tall tires.
I could have stayed with the 5/8's bore MC and gone with the dual caliper system per side that Matco offers which many of the Just Highlanders use.
The dual caliper system would also increase the pedal travel