AirGar

My Feedback: (7)

The scene:

Giant scale P-51 Mustang (World Models)
Moki 2.10 inverted, w/ Slimline Pitts dumping the fumes
Fuel- 5% Power Master w/ 2 oz castor added. Also tried- Performance fuel (Moki mix) 5% as it comes out of the jug. A Klotz synthetic & AA racing castor fuel @ 20% oil content.
Tank sits 2+ inches above carb.
Medium fuel line (5/32?)
Clunk enlarged
A Great Planes fueler that was installed below carb level. (this does not help the siphoning, as we have gravity here on earth ) I added this so I could plug in the "filler" to stop the fuel flow (siphoning) to the carb.
High speed needle at about 5-6 full turns out. Low end has not been adjusted yet. (This is where the setting has been the first couple flights)
Swinging a 20x8 Pro Zinger (break in) 7000-7500 rpm
OS #8 providing the fire


The problem:

Motor seems to run extremely rich at full throttle (in flight, almost like I have a smoke system), however, does not run rich at mid-range. Actually, you can't see any exhaust.

I know the motor is not even close to being broke in, but my concern is this mid-range problem.

I thought about an on board glow tha hooks up to the RX throttle channel, however, I really can't see how this would help here.

It doesn't make sense that I'm getting plenty of fuel at "full", but seems like it's not getting enough fuel when throttled back.

Possible solutions:

1) Low end setting need to be richer? (It's at factory setting) Could this help?
2) Change fuel lines and/or clunk?
3) Add on board glow? (Can't see how this would help, but am willing to try it) Besides, they're so cheap!
4) Re-install motor horizontally? I'd hate to do this as I didn't want to hack up the cowl. The head of the motor would be right where the fake exhaust stacks are.
5) Fuel?
6) Plug?
7) Add a pump?
8) Re-locate pressure fitting?
9) Throw it in the trash?

This is my first Moki, and it seems to be a real power house. The motor DID run HOT the first couple of tanks, and I figured this was due to the combination of the motor being tight and new, and because it's inverted.

A buddy has the same plane, Moki 1.80 mounted horizontally, and does not have any problem whatsoever. (no on board glow, same fuel)

I am at wits end, and could sure use some of you guys help in figuring this out. It won't go UN-appreciated!

Thanks guys,

Gary

bentgear

AirGar, the low end setting controls both the idle and part of the mid range, you may need to richen it up a little to get what you want. If its any comfort, some of the ones I have seen took a while to get them broke in and running at their best. You also might want to go with large fuel line all the way back to the clunk.

Ed M.

AstroMan

Lean out the high end a little to a more realistic setting, then adjust the low speed needle for the idle and midrange. You'll be very happy with the moki..

Rudeboy

MOKI's are "smoky's"... if it doesn't smoke at WOT there's something wrong... so that part is OK.
With this engine you don't determine the "richness" of the mixture by the smoke trail, because compared to other engines you'll end up lean.
Keep it rich for the first few gallons... this thing needs to be broken in, and it isn't going to happen in two flights...
A rookie at our field has a 1.80... I helped him adjust the needles and was baffled for a moment there myself... this thing smokes like hell on castor fuel! Looks nice though on a aerobatic plane.

Now, the midrange problem, if you can call it that way. As I understand it there really is no problem... the engine runs fine, but it doesn't smoke at half throttle.
If your idle is fine, don't touch it. You could of course try to richen it a little, and see how it does...
But it is normal for an engine to not smoke as much at part throttle, because the exhaust will be cooler and the fuel comsumption will only be a fraction of the consumption at WOT.

Fuel draw is obviously fine: if it gets enough fuel at full throttle, it will certainly get enough fuel at part throttle.

jaka

Hi!
Why have you mounted the tank so high?
Common practice is to mount the fueltank so that the center is in line with fuelintake orifice in the carb when the model sits horizontal...this is very important! Your high tank position will make your engine go rich at mid and idle speed which will show up in an engine that doesn't throttle as well as it should (it will not react to fast throttle changes as good as it should)
It might also be that your idle adjustment is wrong ...so just open the idle needle somewhat and listen to how the engine sounds after the change. Don't ever rely on just watching the smoke coming from the silencer. This is not the way you should set and adjust the carb needles. The only reliable way to set a carb on an engine is by listening to how the engine sounds.......

Regards!
Jan K
Sweden
Flying pylonracing for 25years

AirGar

My Feedback: (7)

BentGear & AstroMan,

Thanks guys, I may just try to fatten' up the low end a little and see how she reacts.

With regards to the "large" fuel tubing.... the tubing I'm using now does not seem to have any effect as far as restriction goes, but I will definately keep this in mind.

Thanks again!


RudeBoy,

This thing smoked like my ol' big block Super Tiger! The high end was fine as far a good setting to break this beast in. When it flew, you could tell that sometimes it would come "on the pipe".

Thanks Buddy, I always appreciate your input.

Gary

AirGar

My Feedback: (7)

Not sure why your asking me this Jaka? Does it sound like this is my first plane?

I am well aware of "how" to have the ideal set up, however, I set this plane up (inverted motor/Pitts) knowing I could have problems due to the tank height. Please refer to #4 in my first post.

This doesn't appear to be happening, but I will pay closer attention to the mid range as the motor start getting some fuel thru it. (broke in)


I don't adjust my motors by watching the smoke trail. The amount of turns on my high end needle was noted for reference only, and has absolutely no bearing on the way I run and/or adjust my motors.

Thanks for your input.

Gary

deputydog

Airgar;
Moki's take about 5 gallons to break in!
1. Get large fuel line, period! This will cure 99.9% of your problem. As a guarantee you could also put in a fuel pump. The needles will be rich for awhile.
2. Fuel draw may appear fine at WOT but will definately lean out in the air. This is a big motor and will drink over 2 oz/min, refer to #1.
3. After the 1st gallon the motor will run better and better every tank. Be prepared to lean it 1 click each time.
4. You might want to back off some of the oil. Some companies make a 5% moki blend(Performance Plus) so get some and stick with it. Did I mention to do #1!

Flyboy Dave

My Feedback: (21)

Yo, AirGar....

....send an e-mail off to those ARF manuf. (especially World Models) and find
out why they keep putting those fuel tanks right in the middle of the fuselages....

....what are they thinking ? [sm=stupid.gif]

Dave.

AirGar

My Feedback: (7)

DeputyDog,

After your post, I started thinking about your advice, and the problem I'm having. Do you think that running at WOT it's providing enough pressure to the tank, BUT, at mid range the pressure is being somewhat restricted due the fuel tubing size? Hmmmmmm..... Is this your reasoning?

Next question would be: Would the pressure nipple also need to be "opened" up?

Thanks for your help!

FlyBoy,

Not sure why they do that. I could relocate the tank by modifying the whole front area of the plane, however, I think it would end up looking like an A7 nose with a P-51 fuse/tail.....in other words....ugly.


Gary

tonyc

My Feedback: (4)

Gary;
A few thoughts.
What you call medium fuel line, 5/32 id, Tower calls this extra large. What they call medium is 3/32 id and the large is 1/8 id.

I have 3 of the Moki, the 180 and the 210. I use the 3/32 or the 1/8 id line. The 5/32 gave me problems with air leaks. Probably just me.

I use the Cline on every thing. If you know just a little bit about motors you do not need the Cline but I use the Cline because I hate to de-bug anything. The Cline lets you put the fuel tank any where you want. It just doesn't matter if its high or low or all the way back behind the rudder. The Cline system will push the fuel so that the Moki thinks the fuel tank is 1/2 inch away.

Lots of people have great running Moki's w/o the Cline, in fact I lost pressure on one flight and the Moki still ran great, I could tell on the pull up that something was missing. The Cline just makes things run better.

Just a thought.

tonyc