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h9 1/3 cap zdz 80 comments/questions

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h9 1/3 cap zdz 80 comments/questions

Old 08-28-2005, 03:44 PM
J roc
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Default h9 1/3 cap zdz 80 comments/questions

Finally flew my plane this summer after working on it for 1-2 yrs (having little kids slows down building quite a bit) and now have 35 or so flights on it. This was my first big plane on gas and quite a big deal to me, old news to most of you, due to lack of gas aerobatic planes in our club.
First, the plane is stock with carbon gear, 2 batteries on receiver, no idea on weight, balances in middle of cg range. Hovers at about 1/2 throttle, needs a little down elevator to keep inverted, just breaking in engine and trying some 3d stuff. This is one of the easiest planes I have ever flown, very easy to land, My fears of big planes vanished after my first landing.
I am very happy with the 80, I am slowly tweaking the engine to tune but am scared to lean it to much. I have about 3-4 gallons through it and almost finished its break in period. Engine is very smooth running and not as loud as I thought it would be. I made some very cool baffles which seem to help cool lots. Spark plug has a black color to it. The 32 oz tank in the h9 accessory kit is way to big, I burn off about 1/3 of it on a 10 min flight going to a 20-24 oz tank. I have some questions on the engine though if anyone can help. Thank you.
Do you need to choke engine on every flight or just first of day?
Should spark plug have a tan color even during break in with the extra oil?
Is mid range leaned mainly through low needle or both?
How do I adjust high end? can I keep leaning bit a time as I dont find any difference in tach numbers when I tweak needle.getting 6700 on 26/8 bambula.
manual says 93 octane fuel, I can only find 91 octane, Is there a difference.
Engine sometimes takes 10-15 flips to start. is this normal? does this get better after break in?
this is one awesome plane and I'm sure I could shave 1-2 more pounds off it if I try. next is h9 sukhoi, was going to put in a 100 twin but might get another 80 it is so impressive

Old 08-28-2005, 11:12 PM
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Default RE: h9 1/3 cap zdz 80 comments/questions

J, IF everything is rite on the engine you should only have to choke the first start of the day. If you have to choke every time, check to see if the fuel runs out of the fuel line at the carb, requireing you to reprime the carb. You may have a leak.

If the plug is tan your engine is probably running lean. My 80 has a little carbon buildup on the plug.

Your midrange throttle is set with the low end needle.

To set the high end you need two things. A tachomiter, and the help of a friend (if possible). Run the engine at WOT, lrt it clean out, then get an RPM reading. The goal is to either lean or richen the engine for max RPM. When you get that set, richen the top end around a 1/4 turn. This will lower your max RPM by about 200 (in most cases). Now that that is set you can go to work on the low end needle. All you are looking to get here is a smoothe transition from idle to WOT. If you lean the low end to much you will overheat the engine and you will not be happy with the possible results (flameout to crash). The transition doesn't have to be like a racecar, It just has to be smoothe, no bogs or misses.

If all you have in your area is 91 octane you will be fine. You are tuneing the engine to run on the fuel you have.

My engine start is choke on, flip 6-8 times. Choke off, ignition on flip 1-3 times to start. If yours takes that many flips you may not have fuel to start (lean low end needle).

Your RPM sounds about rite. Kill the engine when you adjust the needles. Much safer that way. Good luck. I hope this will help. Ron

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