skypics

Here is what the internals of the oil pressure sensor looks like. 
John M

Turbo:
My MK4 was painted with butyrate circa 1996. When I bought it in 2016 I could see that the paint was cracked in many places. 
I had it stripped and repainted with Ranthane for a princely sum of $6K. It looks great and I swear it actually seems to have a bit higher TAS.
I have already had some fabric damage when one of my right MATCO brake pucks stuck and took me off the runway and up on the nose and left wing bending the axel, breaking one of the Whirlwind prop blades and damaging left wing tip including the outboard flaperon hangar.
I was going to report it to  AVEMCO, but decided the the $1K deductable would be half of what the estimated repair cost would be and they would most likely raise my premium.
Luckily I have hangar neighbors who have build aircraft who did most of the repairs including scarfing a new trailing rib section onto my outboard rib. 
I had our local fabric guy replace the fabric and the paint shop did the repaint. 
Total cost $2,000.
Interesting sidebar...
When we took the fabric off to access the damage we could see that the same thing had happened earlier in the life of the MK4, but was not indicated in the logs. So the brake puck must have caused the same thing prior.
Keep those MATCO brake puck sliders clean.
 
John M
 

As a Jabiru owner, I see no mag drops most likely because the plugs are both at the top of the cylinder.
Most of my wingmen have 912s and have all reported vibration at one time or other. Had to have the gear box worked on. 
Two friend with Zenith 750s have carb linkage issues which give some issues with both carb throttle levers not working in sync.
Question: Has anyone modified the 912 manifold by joining the two carb inputs so that the engine could run on one carb as the Jabiru does? Instead of the two smaller carbs used on the 912s, the larger carb, as used on the Jabiru engines coud be used. Should work on the 1600 cc Rotax since the jabiru Bing works on the 2200 cc engines. No carb syncing issues.
Doesn't seem that hard to do and would be worth it in my opinion.
That said, I realize there are thousands of 912s doing just fine as is.
John M

I have the bag from Fischer and it has served well for years.  My B model Avid was blue and so the bag is blue. I will call to see if he has maroon to match the paint scheme on my MK4.
John M

niappos
What is the HP of the 670 and what did Rotax do to get the increase? Larger pistons? Different stroke? Higher RPM?
John M

Nlappos
I was referring to the 582.
I see your belly mound has been modified since the earlier photos . You have left a much larger gap and maybe that allows the heat from the muffler to avoid the cooler.
You do see how the heat from the muffler will flow back to the cooler?
Looks like a LOT of extra drag, but you are satisfied and that's what matters.
John M

 
nlappos
The heat from your muffler will go directly into the belly mount radiator. Been there..done that.
Best cure is to have a gap between the fuselage about the same distance as ypur current stand off. Your current solid stand off can cause the air flow at the belly mount to stagnate because the air flow at the top is blocked.
I had an aluminum sheet that took the heat from the muffler and directed it over the top of the cooler through the gap. This was on my model B when I was driving a 582. The model B had a side mount radiator that wasn't efficient. So I added the belly mount. with the gap to let the aluminum sheet guide the muffler heat over the top of the belly mount.
If you don't direct the muffle heat over the belly mount you will run hot.
That said, your cheek radiators should be plenty of cooling. You just have to be sure the air moves through them...not around them.
We fly in the heat of SoCal and we removed the belly radiator from the MK4 my friend bought. We could not get the temps down.  We bought and installed the cheek radiators. They worked well. So we removed the belly mount and saved the weight and drag.
Finally, your transponder antenna will partially blocked by the belly mount. Again...been there ...done that. So this info from experience.
John M

Wing Cuff photo...
This is the wing of a MK4.
John M

To that 100 pounds you can add 16 pounds for the  muffler and another 10-20 ponds to the water cooler(s) and water.
When  removed my 582 to install the Jabiru 2200 I weights everything and came up with 130 pounds. I did have two cooler in serieds for sufficient cooling and this took 1 gallon of water at 8 pounds. The Jabiru weighs 135 ponds full up so  didn't have a weight problem, but the CG was farther forward for the Jabiru.
Jon M
 

Here is a shot of my wing cuffs.

Jim:
My cabane gear is completely faired including the springs and the mid junction plate, as I mentioned. I'll get a better photo today and post it.
I also have gap seal tape at the elevator and rudder gaps. All struts, wings and horizontal are faired. And as I mentioned before, I have installed wing strut cuffs.
My cruise is 90-95 MPH TAS at lower altitudes and 100-105 up above 10,000 MSL. This is at 2900 RPM with my Jabiru 2200.
John M

Have the spring bush gear and have had no issues in the rough backcountry strips.
I have put aluminum fairings over the springs and faired out the flat plate where the spring struts meet.
Avid MK4 STOL wing.
John M

I removed my injector, not because of failure worries..although it is another moving part that can fail, but it is not common. I changed because I was using 100% synthetic at 100:1. 
As I recall from my 582 days, the injector was designed to inject at 70:1 below 3,000 RPM to eliminate oil loading on the plugs at idle RPM. Then it changes to 50:1 above 3,000 RPM.
Since I was at 100:1 it was not needed. Plus the engine ran much cleaner. I was running 91 octane mogas at a time when it didn't have ethanol.
John M

Vance
The cap was installed from the 12-volt buss bar to the ground buss.
What radio are you using? Is the wine appearing on your intercom or from the radio receiver?
I have found that most ignition interference can be eliminated by using a good common ground. If you have grounds at various locations behind your panel you can cause "ground loops." 
You may be able to use the primer if you slowly push it in. Do this with plenty of altitude so f you kill the engine you have time for a restart.
Looks like your Avid is a MK4. My MK 4 also has 3 false ribs between the main ribs. My model B only had two. A friend had a MK4 that had 4 false ribs between the mains. Are your wings underchambered?
John M

When you run the auto compression test...not the leak down test...make sure the throttle is wide open to get the best reading when you crank the engine. I just did one on my Jabiru and got around 160 PSI on all four. I believe I used to get 120 PSI on my 582.
 I have flown behind the Rotax 2 strokes for over 3,000 hours. This included the 447, 503 and 582. Most of it was done in ultralights and then in AvidFlyer experimental aircraft.  The avid is now powered by the Jabiru 2200.
 I have had a good reliability experience with the Rotax, but opted for the Jabiru as opposed to the Rotax 912 due to the high cost of the engine and parts plus the complexity makes the installation very cramped in my Avid Flyer. I also wanted better fuel economy and liked running at 2800 cruise as opposed to 5800. The only drawback is that I used to swing a 70" WARP but with no gearbox, I now swing a 66" Whirlwind prop. 
My climb rate with both engines is about the same for the 64 HP Rotax as opposed to the 85 HP Jabiru. I also like the sound better. Easier on the ears because most ANR headsets are designed to reduce sound in the 2000-3000 RPM range. The higher frequency of the 582 gets through.
Rotax recommends a TBO of 300 hours on the 582, but I used to get around 500 hours TBO. This is because I flew often. No winter shut down due to winter weather here in SoCal. I used 100% synthetic oil at 100:1 ratio so the oil injector was not necessary and was disabled.
I am surprised that you can get 6500 RPM on a ground static run. In my opinion, you don't have enough pitch in the prop. If you get that on the ground this means you can over rev the engine in level flight. You should get a better cruise with a bit more pitch.
A compression test is required for condition inspection. That said, my A&P never did one on my Rotax or my Jabiru, but he has since passed and the new guy wants one.
Hope this was of some help.
John M
 
 
 

I have cleaned up the strut cuff modification. I now see no turbulence behind the strut/wing junction. 
I referring to my under chambered STOL wing. You may not see the turbulence on the speed wing
Those with the STOL wing...
Next time out flying in level cruise look out at the fabric behind the strut/wing junction and see if you see the fabric buffeting. This is what attracted my attention to this area.
If you do see the buffeting, just place some yarn or string behind that area and notice what the telltales do in climb and in cruise.
John M

Jim
 
I have the cabane gear on my MK4 and love the extra 10" width.
I also faired the springs with some aluminum fairings just in keeping with my efforts to reduce drag at everywhere possible. I even put fairings on the flat plate where the leg struts meet in the middle.
This is not a great shot, but you can see the fairings I am referring to.
The one in the middle was made by using two chrome spinners front and back. This helped eliminate about 24" of flat plane on the gear.
John M

North Idaho:
We usually fly to Idaho in late June.
When I drove a 582 I didn't need metal plug caps. I did install a 20,000MFD capacitor across the 12-volt line and used the resistor plugs that took care of the ignition wine. 
Also, make sure your kill wires are shielded and the shield are grounded at one end only and don't run close to any avionics wires. They really put out the noise. To check if they are an issue rev the engine up to where it makes wining noise and switch from left to right mag and see if there is a reduction when you are only on one mag.
To check carb richness when in cruise slowly pull o the enricher. If RPM increases you are too lean. If it bogs down your are too rich. This has worked for me.
I don't see the need for VGs. The flaperons do a great job of keeping the air attached to the wing at high angles of attack. Sure, you can land at a higher angle of attack, but that just makes the tail wheel hit first then the mains.
I touch down at 40 MPH clean and 36 with full flaperons.
I have flown into many short and narrow Idaho strips including Mile High with no need for VGs. They also make it more difficult to clean off the wings.
You should have many fun times in the Avid and who knows if the company starts up again we should be able to buy replacement parts.
Buy the way, my MK4 has a lot more leg room than my model B did. I like that a LOT and I am only 5'8" tall.
For your long camping trips, you will want to buy the hanging bag from Fischer Upholstery 208-939-6513. It also serves as a duffle bag when you land and go to a hotel for the night.
If one wing seems heavy you can adjust the Hein bolt on the rear left wing strut to get the trim right. 
John M
 
 
 

Turbo
 
Congrats on your first flight.
I flew with the Rotax 2 stroke for over 1,000 hours before switching to the Jabiru 2200 on my model B.
Here is my input on some of the questions you have...
I don't recommend a prop clutch. As was mentioned it will limit your glide ration about 20% and you can not hand start the Rotax, which you WILL do one day.
I had the E box on my Rotax.
I totaled my B model so I will be referring to my MK4 in this response.
My IAS at stall is 40 MPH clean and 35 MPH with 13 degrees of flaperon. Stall is just a bob up and down. I have a Dynon D10 in the panel and it has an AOA indicator with audio alarm for stall indication.
If you have a wing low trim you can adjust the rear left wing lolly pop attachment to raise or lower the rear part of the left wing to get the trim right. It doesn't take much.
Don't put more than 15 degrees as your flaperon down angle. On your model, the roll rate gets slower and if you put in too much down flaperon you can get reverse control. You put in left stick and the right wing drops and visa versa.
As concerns your rough low RPM you will need to be sure your carbs are balanced and your idle jets are clear. You should be able to idle at 2000 very smoothly.
It is easy to flood the upside down engine on the Avids. To prevent this, don't use the primer until you are actually cranking the engine.
Make sure the flange on your thermostat has a couple holes drilled in it if you have a grey head engine. Here is why. If you are on a loooong final with the throttle pulled back the water in the radiator will cool down quite a bit, especially in winter flights. Then as you are landing you decide you need to go around. You put in full throttle and on climb out your thermostat opens and floods your hot engine with cold water. Could cause a problem.
I ran a 70" wood two blade prop and cruised at about 75 -80 MPH at 5800 RPM.
I ran 100% synthetic oil at 100:1 ratio so I disabled the oil injector. 
I used to get 300-500 hours TBO on my engine.
I had VGs on my model B, but have determined not to put them on my MK4. You can get a bit slower touch down, but the angle is so high that the tail wheel touches first and then the mains slam down. The flaperons do a great job without the VG. I also use a bit of flaperon for nose down trim while in cruise.
With the Jabiru I cruse ar 90-95 TAS at 2900 RPM burning 3.0 GPH. Since it is direct drive the max prop length is 66".
That's all I can think of at present.
I now have over 3,000 hours in Avids and am completely satisfied with my MK4.
We fly to the Idaho backcountry each year where the Avid really excels. I flew it to OSH two years ago.
Have fun flying your avid.
 
John M
 
 
 
 

nlappos
 
Thanks for the info on the Avid cargo bag.
John M

Very slight performance change, but each small fairing helps and adds up. 
John M

When I was driving a 582 I learned early, especially on an Avid with the engine upside down, to only use the primer when the starter is engaged. Otherwise, the engine could quickly flood and the plugs had to be removed and cleaned.
 
John M

I finally made some wing strut cuffs that severely cut down the turbulence behind the forward wing strut and leading spar.
John M

There are several ADSB in only units out there that will show traffic and weather. It will not show where you are and does not comply with the 2020 ADSB mandate.
I have the Uavionix ADSB in/out installed on my MK4 and can get all my target info using IFLY GPS on my phone or tablet.
This unit weighs ounces and is installed in 30 minutes and the one for experimental costs about $1400. 
I am a midair survivor and would not fly without it.
John M 

Vince:
 
Nice shots. Hope to see you sometime when I make my annual flight to the Johnson Creek base camp. The breakfast at Sulphur Creek is MUCH better than the one at Flying B.
John M