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Maverick Atom 80 Power loss at full throttle (Engine only 3 hours old)


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Hi All
 
I need your help please!
 
Engine lifespan:
I've flown my new Atom 80 Maverick 3 times, after purchasing it at the beginning of winter. My third flight was from 3-4 hours of the engine's life, excluding the run in time. I ran in the motor meticulously and I'm still running on the richer 2% oil mix per the manual. I'm using Motul 800 synthetic 2 stroke oil as suggested.
 
3rd Flight Problems:
Warmed up the motor as suggested in the manual. Before taking off, I ran the motor a full throttle for 10-15 seconds. 30 minutes into the flight I lost power at approximately mid range revs. The engine performed fine at low - mid revs, but as soon as it got to about 5-6k (guessing) or just before the power band, the engine would loose power until i released the throttle. I limped home and landed safely with the available engine power.
 
Solutions I've tried:
I checked for air bubbles in the fuel lines to ensure there were none. There was no air bubbles throughout my problem solving and testing.
 
I warmed up the motor for about 4-5 minutes, idling then reving to about 4-5k revs. I then powered to where the motor felt comfortable at about 8k revs. But then at full throttle the engine lost power until I released the throttle. The power loss is almost instantaneous once at full throttle.
 
I checked the spark plug. As expected it is dark brown to soot black due to the 2% oil mix. Cleaned and screwed back in. Tested again and power loss persisted.
 
I removed the rev counter wire I had wrapped around the coil/spark plug wire, as I heard this can sometimes cause power loss. Tested and power loss persisted.
 
The Atom 80 does not have a High Speed Adj. (H) on the carburettor, so I turned the Low Speed Adj. (L) clockwise/closed 1/4 turn to reduce the fuel flow. Tested and power loss persisted. Considering the manual warns to only turn 1/8, I did not try further. I checked the spark plug which was now running grey to soot black, so I turned the Low Speed Adj. (L) anti-clockwise/open 1/4, back to factory setting.
 
I replaced the petrol as I wasn't sure how old, old is until the fuel looses its effectiveness. Tested and power loss persisted.
 
Any suggestions?
 
JC
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Petrol loses its effectiveness very quickly. In addition if its not ethanol free it will absorb water and once that hits your fuel filter and the carb you can get the same symptoms you are describing. If it was my motor I would be thoroughly cleaning the whole system, filling it with brand new premium petrol and see if that helps.

 

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9 hours ago, Jean-Claude said:

 the engine would lose power until i released the throttle.

 
 at full throttle the engine lost power until I released the throttle. The power loss is almost instantaneous once at full throttle.
 

Suggests a weak mixture or fuel starvation to me, a strip-down and inspection of the carburetor would be the first thing i`d do - but yours must be under warranty so you can`t touch it? A kinked fuel hose? Filters clean?

Could be a piece of dirt/lint that was there during the machines` manufacture has now been drawn into the carb in the first few hours.

You`ll have to talk to whoever you bought it from (dealer) and get them to repair under warranty?

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11 hours ago, MattMc said:

Petrol loses its effectiveness very quickly. In addition if its not ethanol free it will absorb water and once that hits your fuel filter and the carb you can get the same symptoms you are describing. If it was my motor I would be thoroughly cleaning the whole system, filling it with brand new premium petrol and see if that helps

Thanks Matt. I flushed out the system and did not help. Although I didn't try premium petrol, but this shouldn't be needed.

 

JC

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I know exactly what problem you’re talking about as I’ve experienced exactly the same thing. Twice in flight (very disconcerting) and loads of times on the ground. I’ve had the carb stripped, cleaned and changed, checked fuel lines, clunker, primer, spark plug, you name it I’ve checked it (with the exception of the coil). In fact it’s what kept me from flying this weekend.

 I’ve done a bit of research and see that Vittorazi have changed the  carb totally for the '20 model. The new one now has a high range needle "for those in colder climates". My thinking is they've acknowledged that there is a fuel issue and done something about it. (they've also changed the reduction drive). I'm going to see if I can get hold of one of the new carbs and see if that makes a difference.

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Hello JC, Hello Chris.It also happened today with one of the Pilots at Membury, who was also on a new Atom 80.He had just got off the ground, perhaps 10 ft and full throttle when the engine power suddenly dropped and he made a forced landing. This happed 3 times in the space of 20 mins.I really hope this is not indicative with the Atom as I too own one which has just about 5 hours on it.🤦‍♂️

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This seems to be a theme. I experienced this issue yesterday at about 50 ft after take off, releasing the throttle to about 1/2 and reapplying and it cleared. I had to do that 3 times. The rest of the 20 minute flight (close to the field) was fine. My Atom 80 has less than 5 hours on it and I'm using fresh fuel with Motul 800 oil as recommended. Nothing obviously amiss with the kit. Worrying.

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37 minutes ago, Flypapuk said:

My school 19 and 20 are running flawlessly, but I have seen the problem and it was definitely air related ( bubbles in the fuel line ) 

There are different issues then because mine was not bubble related. None in my fuel line when  the issue manifested itself. Given the number of units affected this weekend at Membury, I’d also hazard a guess and say they weren’t either. 

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What Vittorazi says about the problem is the WG8 carb fitted to the '19 models isn't up to the job if the air temp gets cold. Hence on the '20 models they now fit the WB carb.

Not bubbles, just no good in the cold.

I've a replacement carb on its way and will see if that makes a difference.

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I'm not familiar with the Atom 80, but so many people reporting the same issues might point to carb icing (restricted venturi caused by the formation of ice when moisture freezes on cold surfaces as the pressure drops, or something like that!).  Larger aircraft have carb heating, and carb icing is checked before take-off.  The annoying part is that the ice melts quickly once the engine stops, so it can be very hard to diagnose. 

https://www.boldmethod.com/learn-to-fly/aircraft-systems/dont-let-carb-ice-happen-to-you/

It was cold and moist in Salisbury, I assume there were similar conditions at Membury?  Just a thought.

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From the article: "The temperature range where carb ice can occur is equally surprising. According to the FAA, carb ice is possible from 10F to over 100F, with serious icing possible from 20F to over 90F (-7C to 32C)."

In Salisbury it was 32F, with a 32F dew point (judging by the fog).  This is in the 'serious icing' region on the diagram.  

What were the conditions at Membury?

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Maybe your high speed circuit is too lean for the weather, because there are certain circuits in the carb that come on at different air flow demands (throttle position) where yours is unhappy with lots of throttle.   See attached chart to get the idea (from the mikuni sbn manual).  Since you're flying in cold weather, it's probably a lean condition.  

Also, check for air leaks (crankcase may be leaking 2t fuel) and check the reeds.

3fq334.PNG

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Hi All

Thanks for the replies.

Additionally to the solutions I tried I also replaced the spark plug but the problem persisted.

Sending my unit back to Parajet. The problem seems plain to see based on the consistency of the comments here. But I'll have to wait and see if they cough up for a new carb. if this is the issue.

I'll let you all know how this pans out. I'm not holding my breath for a quick and easy resolution, but hopefully I'll be pleasantly surprised.

Regards,

JC 

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On 19/01/2020 at 16:55, Pete S said:

This seems to be a theme. I experienced this issue yesterday at about 50 ft after take off, releasing the throttle to about 1/2 and reapplying and it cleared. I had to do that 3 times. The rest of the 20 minute flight (close to the field) was fine. My Atom 80 has less than 5 hours on it and I'm using fresh fuel with Motul 800 oil as recommended. Nothing obviously amiss with the kit. Worrying.

Hi Pete

Generally, I'm also worried. Thankfully both you and I had problems with enough altitude to recover. I won't fly it again until Parajet have looked at it, but I consider it a safety issue should this happen at take off. I would like to think with Simon and Collin's training that I would be able to handle the situation, but I'd rather not find out.

JC

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I am still convinced is something to do with the primer bulb myself. Back in the day, I had a RAD Paramotor lol yes I know.... But it did not have a primer bulb so I fitted on and the exact same problems happened. 

I took it back off and the problems went away. My guess is that it was acting as a very slight restrictor or needed a certain tiny amount of pressure before fuel would flow through it. I honestly don't know. I just know it worked then and the symptoms were identical 

It's not something I have heard about for about 15 years, but as soon as it popped into my head I convinced myself. :-)

SW :D 

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