Please Help - Predator Carbon Gasser w/ Hanson Pro G26 -

[rfaster]

Would appreciate any input on this - I'm about at my end point with trying to get this thing tuned to FLY -- Over 7 Hours turning needles, starting motor - walking back - spinning up- engine DIE etc....

I picked up this kit used - was told the Heli and Hanson Pro had 2 gallons of break in fuel/oil run and it was just used for AP. I was told this kit ran good - no issues etc... If I fill the tank to the STOPPER I notice that i get leaking out of the stopper... (not sure if this will help ts or not)

I have another Predator gasser with std G26 and am able to tune - it runs great etc...

I ran 1/2 tank with Amsol 2.5 ounces to gallon - then when I spoke to Hanson he said I should up that to 3.5 - (Both mixes result in the exact same behavior).

I start the Hanson G26 at 1 1/2 on both needles (per Mr. Hanson) - and the engine sounds good - picks up speed and right when it gets to lift-off the motor just QUITS - or drops into IDLE... if I richen the high needle in 1/8th increments - it gets a little better - and lets me hover for a minute maybe 1.5 minutes before dropping back into Idle. I continue to increase by 1/8ths until Its too rich to fly. I have spent over 7 hours just adjusting the needles from one turn out - and 1/8th incremetns on both needles until its too rich to start.

[rbort]

Something else is wrong. How about fir starters take off the canopy and look at the throttle servo as you throttle up. Get into a hover and see what the throttle servo does 1.5 minutes later when it goes to idle as you say. That that move? Does the engine just choke? Possible problems:

a) bad servo
b) bad muffler (muffler getting blocked)
c) air leak

Air leak can happen and worsen when engine warms up. If this is happening check the engine for oil leaks. Check the insulator area, and check the front bearing. Heat expands aluminum so you see a problem after the engine warms up.

-=>Raja.

[rfaster]

rbort - brand new futaba 9451 servo's all around (throttle etc...) running 6V. From start thru the curve the servo movement and butterfly are smooth and in the correct direction.

Muffler - whats the best way to tell if its restricting airflow? I took it off and it appears that its not congested (again - I'm told this stock muffler was Never used - infact it came installed up-side down on my heli)

I'm new to Gas engines -


What is the Insulator area -
Front Bearing - is this a visual inspection - or will I need to tear down the motor?

I noticed that gas leaks from the "STOPPER" in the fuel tank when I fill above the stopper -- Could this be an issue?

[rbort]

No the leak from the tank is not the cause but do fix it just so you don't lose fuel or get fuel on your electronics.

Stock box muffler is probably not blocked my guess. I had blockage with 4030 rear can muffler due to carbon buildup but that was after years of use. I'm just brain dumping issues I saw so you can check and make sure all OK on your side.

New servo or not, take the canopy off, hover it and watch the throttle servo until the problem occurs. It may shed some light on your issue.

The front bearing oil leak check is a visual thing. But you have to take the fan off the engine to see if its leaking from there. Do this last when all else fails as its more work than other things. Again I had that as a problem in the past -- engine would run good for 1 to 2 minutes and then it would just lose power and sound like it got filthy rich and sink down from a hover due to loss of power.

-=>Raja.

[rfaster]

rbort - what you describe "loose power and sound very rich - sink down" that's exactally what happens! It either dumps down into IDLE condition - or just shuts off completly - depending on how rich my H needle is.

On the canopy - I have yet to put my canopy on this bird yet :arggg: Have a nice new purple checker Century canopy that I'd love to put on if I could get this damn thing flying for more than 2 minutes. Today I was paying special attention to the servo - and when I lost power - as I gained RPM and it seemed to go to the H needle my servo did not do anything non linear - it followed my throttle curve.

I guess what really gets me on this HEli - as it was advertised to be in GOOD/engine only 2 gallons like new condition - I can't imagine how the seller was able to fly when I can't get more than 2 minutes... it just blows my MIND. So I assumed it must be something VERY simple - so far not so much.

Someone also suggested to check gasket on the carb -- I see lots of folks who upgraded to the alum piece that RC sells - I compared the carb to the carb on my flying G26 and the look the same - Guess I can take the problem one off to check to see if I'm sucking air.

[rbort]

The Z-rc aluminum upgrade will only fix a problem if it exists. If your insulator is cracked and leaking from there then it will fix it. If its not cracked then there will be no difference in performance if you replace it with an aluminum one.

What happens when the thing slows down? Does it still idle nice but it won't throttle up? I just got an idea. Pull the spark plug off and check the gap. There may be a piece of carbon lodged in the gap that is causing this issue. If not check the gap, should be around 20 to 25 thousands, in that range -- usually how the plug comes out of the box is good enough (no need to change from that).

-=>Raja.

[rfaster]

ok - with 1 1/2 and 1 1/2 on both needles - heli starts good - gets good headspeed- and right before it lifts off it cuts out and goes to idle.. if I let it slow all the way back down - I can spin it back up and it will cut out at the same point. If I increase the high needle by 1/8ths I can get the heli to actually hover for max 1.5 minutes ... then it falls back to idle (at 5 feet off the deck - felt like mini Auto's until I realized what was happening) -- the next 1/8th richen on the High Needle - gets so rich I can't run the engine.

I pulled the plug from Predator #2 - which fly's great and swapped it today --- set needles back to 1 and 1/2 --- and it did the very same thing - identical - so I eliminated the plug.

[MarkWebber]

Much the same thing happened on mine when I initially got it flying. After much frustration, I found the setscrew for the throttle lever was not holding securly and the butterfly would close in flight. Landing, closing the throttle and restarting would cause the symptoms to replicate themselves. Needle changes did much the same thing as your describing. Of course, securing the throttle lever fixed this problem.

[Tom Fiddler]

Sound to me like you are going into failsafe of some sort.
When you say it "falls back to idle" ... does it continue to idle until you lower the stick and raise it again?
This is how it would act if you had a GV-1 and it see's a low battery voltage.
Just a thought, tell us more about your radio equipment

[rfaster]

Tom,

On this Predator I'm not running a Gov - Just a Pred Carbon SE with Hanson Pro G26 motor - GY611, 9451's All 6 V setup with G3 receiver and 4800 duralite rec pack and regs. I rulled out failsafe since I still have full control of the heli - when it cuts out - I can leave it ideling on the ground ... if I punch it at this point it will just die - but if I go very slow --- I can get a bit of head speed back up - but never as much as starting from a STOPl.

[CustomPC]

How is your tank vented?

Sounds like you have a restricted vent which creates vacuum in the tank when you try to draw fuel too fast.

[rfaster]

CustomPC - I have a vent at the top of the tank - with a 3mm vent tube on it - actually all of the fuel tube on this predator is 3mm -- whereas my other predator has all 5MM - not sure if this makes a difference or not.

I'm also starting to get a bit more leaking from the fuel tank - I thought it was from the stopper area - but now am not sure since I put a ziptie on the stopper and still get the leak.

[Rodney]

This is how I found problems with electronics in mine. Remove blades and try to spool it up but paying very close attention so it dont over speed. If there is a servo or reciver problem you will find it there. I do this on all my machines when first starting them. On my second gasser I found bad elevator servo that was new right out of box. Heli would have crashed as it didnt fail unless heli was spooled up. On bench it worked fine and also at idle. If that doesnt solve your problem change you plug if you havent already done so.

[rfaster]

Rodney - on my first start I spooled up w/out main blades - all was good. I'm starting to think I may have a problem in my fuel system (tank, fuel tube etc....) Heading out on a business trip and hope to get some time at the end of the week to troubleshoot this more.