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About skypics

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    Advanced Member
  • Birthday 08/08/1937

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  • Gender Not Telling
  • Interests Guitar, Piano, Ukulele, Harmonica, my two Maltese dogs, Flying backcountry strips in my Avid MK4

skypics's Activity

  1. skypics added a post in a topic Speed fairings   

    Here is what the internals of the oil pressure sensor looks like. 
    John M
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  2. skypics added a post in a topic Fabric touch-up   

    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
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  3. skypics added a post in a topic What's it trying to tell me ?   

    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
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  4. skypics added a post in a topic Hanging Luggage Bag for Avids   

    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
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  5. skypics added a post in a topic New Rotax 670 Install   

    What is the HP of the 670 and what did Rotax do to get the increase? Larger pistons? Different stroke? Higher RPM?
    John M
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  6. skypics added a topic in Rotax and other engines   

    Jabiru Engines
    I think I have posted about this before, but it needs repeating.
    I have pulled the heads on my Jabiru 2200 several times and each time I have had this problem.
    The hydraulic lifters on the pulled head do not relax after reinstalling the head.
    This causes the valves, sometime only one, but many times both to be partially opened.
    You will be able to see this by comparing the position of the valves on the head you didn't work on. They will not be as far out and near the edge of the rocker box edge as the untouched head. 
    So when you turn the prop by hand you will find one cylinder with no compression. If the intake valve is held open too, you may see one of the other cylinders with no compression because of lack of vacuum.
    If this happens you have a couple choices:
    A) remove the head again and pull the lifters and soak them to get all the oil out. You should be able to compress them when they are clean.
    B) Start the engine and let it run roughly until the oil temperature builds. This can take 5-10 minutes. You should see the EGT start to build on the soft cylinder and then after the oil is heat soaked the hyd lifters will relax and the engine will smooth out.
    Flew it for an hour for check out. All is well now.
    John M
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  7. skypics added a post in a topic New Rotax 670 Install   

    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
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  8. skypics added a post in a topic New Rotax 670 Install   

    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
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  9. skypics added a post in a topic Speed fairings   

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

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  10. skypics added a post in a topic New Rotax 670 Install   

    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
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  11. skypics added a post in a topic Airdale's Bush Gear   

    Here is a shot of my wing cuffs.

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  12. skypics added a post in a topic New legs for the Avid   

    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
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  13. skypics added a post in a topic Airdale's Bush Gear   

    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
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  14. skypics added a post in a topic Another engine out from an oil injection failure   

    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
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  15. skypics added a post in a topic Mountain Avid finally Flys   

    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
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