admin (Simon W) Posted January 21, 2020 Share Posted January 21, 2020 I have been flying the school machine all through the weekend and it has had no issues at all. All very bonkers. SW Quote Link to comment Share on other sites More sharing options...
chrsfrwll Posted January 21, 2020 Share Posted January 21, 2020 3 hours ago, Jean-Claude said: Chris, did Vittorazi replace at their cost or have you purchased the replacement carb? Regards, JC It’s being done under warranty. On their website (under News) they mention there is a free upgrade kit for those with ‘19 models to bring them in line with ‘20 models, though it must be done via dealers. Not sure what the carb is though. Quote Link to comment Share on other sites More sharing options...
chrsfrwll Posted January 21, 2020 Share Posted January 21, 2020 1 hour ago, admin (Simon W) said: I have been flying the school machine all through the weekend and it has had no issues at all. All very bonkers. SW That’s the bit that’s so frustrating. There is no pattern so difficult to diagnose. All it does is create worry and lack of trust in the kit. Quote Link to comment Share on other sites More sharing options...
Pete S Posted January 21, 2020 Share Posted January 21, 2020 Following my incident last Saturday I flew 3 times yesterday without any issues with the engine. The outside air temperature was similar on both occasions. It may be useful to have a straight connector handy to replace the primer bulb in order to prove/eliminate Simon's theory should the problem reoccur. Quote Link to comment Share on other sites More sharing options...
chrsfrwll Posted January 21, 2020 Share Posted January 21, 2020 I’m going to pick up a load of fuel line when I next go to Parajet Quote Link to comment Share on other sites More sharing options...
steelmesh Posted January 22, 2020 Share Posted January 22, 2020 For people diagnosing this: In the Walbro Manual, Page 12 has a few things to look at regarding "Poor High Speed" Quote Link to comment Share on other sites More sharing options...
powerlord Posted January 31, 2020 Share Posted January 31, 2020 this is the kinda thing I was talking about on the other thread. I twice had exactly this happen on my top 80 - twice I had to land out as I couldn't get enough power out the engine to stay level. twice, I stripped the carb down, took it off, checked the petals, yada yada, carb kit, new gasket, stuck it all back together and it started working again so I was none the wiser. Like here, I got 100 different reasons for what the cause was. If you've not already - that'd be what I'd do. chances are it is some little tiny thing - a small gap in the gasket, a slightly loose petal, a tiny bit of crap in the carb. Rather than spend ages trying to get the root cause, just take 2-3 hours to strip it all down, replace gasket, do carb kit, torque everything up right and I bet it goes away. These feckers fully implement chaos theory - looking for a specific cause it like looking for tits on a bull. Quote Link to comment Share on other sites More sharing options...
cas_whitmore Posted January 31, 2020 Share Posted January 31, 2020 Quote Link to comment Share on other sites More sharing options...
MIke Page Posted February 9, 2020 Share Posted February 9, 2020 (edited) This vid may be useful if you have an ATOM 80 Edited February 9, 2020 by MIke Page typo Quote Link to comment Share on other sites More sharing options...
MIke Page Posted February 9, 2020 Share Posted February 9, 2020 (edited) double post deleted. Edited February 9, 2020 by MIke Page double post Quote Link to comment Share on other sites More sharing options...
Jean-Claude Posted February 29, 2020 Author Share Posted February 29, 2020 HI All Thank you everyone for your input. I have digested it all to try and get a handle on this and to ensure my experience grows to keep safe. UPDATE: I received the motor back from Parajet. Once the motor was out of the queue and on the workshop floor it took a day to diagnose, test and courier back to me, to receive it 2 days later. I didn't get much feedback, but the MY19 carburettor was changed to a different model/type with the word "Walbro" molded into the casing if you look at the motor from the back. I assume it is the MY20 model, not sure. I tested the motor this morning. (6 degrees C, 62% humidity) The video below is taken after 5 minutes of idle and low rev warming up. I've done nothing except put the spark plug in. There was still about 0.75 litres of fuel in the tank, so did not top it up for the test. FURTHER PROBLEMS: At first the power output seemed smooth and linear to max revs. There was no stalling at max revs! Yeah. This was my original problem. However, after further testing I found that the power climb to max revs was perhaps sluggish. I'd remembered a far more quicker response and rev climb to the throttle before the carb. change. Then after testing at mid/low revs it stalled multiple times. (See video below for 2 of the stalls) QUESTION: Could I please get your opinions on my throttle control? I can't think that this is user error as I should have full control of the throttle for a safe flying environment. I cannot fly like this. I have no trust in the motor. Regards, JC <iframe width="560" height="315" src="https://www.youtube.com/embed/jZBTJ8PMDxQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> Quote Link to comment Share on other sites More sharing options...
Guest Posted February 29, 2020 Share Posted February 29, 2020 Its not user error thats for sure. Looks and sounds like simple fuel starvation. I say simple but probably not simple to work out why. I would start with the basics. Check the vent on the tank but it seems to happen a bit quick for that. I would put some more fuel in too just to eliminate that. It does look a bit slow to respond to throttle inputs too.. Have you got someone to watch the fuel going through the lines as you are running it? Quote Link to comment Share on other sites More sharing options...
Jean-Claude Posted February 29, 2020 Author Share Posted February 29, 2020 1 hour ago, toploader said: Its not user error thats for sure. Looks and sounds like simple fuel starvation. I say simple but probably not simple to work out why. I would start with the basics. Check the vent on the tank but it seems to happen a bit quick for that. I would put some more fuel in too just to eliminate that. It does look a bit slow to respond to throttle inputs too.. Have you got someone to watch the fuel going through the lines as you are running it? Thanks Top I will look into this. Quote Link to comment Share on other sites More sharing options...
admin (Simon W) Posted February 29, 2020 Share Posted February 29, 2020 If you want to take a spin down tomorrow, we can just do a quick check of your primer. (bypass it temporarily, to see if it solves the problem) which I am convinced it will. SW Quote Link to comment Share on other sites More sharing options...
Jean-Claude Posted February 29, 2020 Author Share Posted February 29, 2020 2 hours ago, admin (Simon W) said: If you want to take a spin down tomorrow, we can just do a quick check of your primer. (bypass it temporarily, to see if it solves the problem) which I am convinced it will. SW Thanks Simon and thanks Pete who offered the same, but I need to strip and seal the shower tomorrow. I've ordered piping to test this, but if I struggle I will take you or Pete up on the offer another weekend. If it is this something to do with the fuel line, it should have been picked up by the Parajet engineers when it was with them. It took a noob, me, 5 minutes to pick up this problem. BTW, could you please speak to someone about the weather! Regards, JC Quote Link to comment Share on other sites More sharing options...
admin (Simon W) Posted February 29, 2020 Share Posted February 29, 2020 Mate in all honesty, I am not 100% sure it will solve the issue.. I am though 90% sure it will. I have mentioned this to the guys as PJ who I suspect did not test the idea for whatever reason. Happy to help if needed, but it is a simple test (Just make sure the pipe is secured and cant reach the prop or exhaust) Can't wait to hear your findings. SW Quote Link to comment Share on other sites More sharing options...
Guest Posted February 29, 2020 Share Posted February 29, 2020 I know this might sound stupid but is .75 l of fuel enough? Is the clunk fully submersed? could be something as simple as that! Quote Link to comment Share on other sites More sharing options...
Jean-Claude Posted February 29, 2020 Author Share Posted February 29, 2020 4 hours ago, toploader said: I know this might sound stupid but is .75 l of fuel enough? Is the clunk fully submersed? could be something as simple as that! If it was not enough then bad on me. However, after the second stall in the video I checked the fuel line and it had no bubbles or intermittent air gaps. Going on logic, as I'm still feeling my way through this, I think I would have seen air in the line. I'm going to stop posting after this until I have something more concrete to come back with, but if I look at this objectively, it' shouldn't be the coil as there would probably be more sputtering, I changed the plug twice, the carb. has been changed so the odds on a fault there are now seriously high, I don't think it's the air valve into the tank as I vaguely remember originally testing without the cap on, so that leaves the fuel line. There is a high probability that Simon has been right all along, in his words a 90% probability. I will try and test for the fuel tank air valve and more fuel tomorrow and test for the fuel line next weekend. Thank you all! JC Quote Link to comment Share on other sites More sharing options...
cas_whitmore Posted February 29, 2020 Share Posted February 29, 2020 Don’t stop posting , it’s quite on here Quote Link to comment Share on other sites More sharing options...
Guest Posted February 29, 2020 Share Posted February 29, 2020 40 minutes ago, Jean-Claude said: If it was not enough then bad on me. However, after the second stall in the video I checked the fuel line and it had no bubbles or intermittent air gaps. Going on logic, as I'm still feeling my way through this, I think I would have seen air in the line. I'm going to stop posting after this until I have something more concrete to come back with, but if I look at this objectively, it' shouldn't be the coil as there would probably be more sputtering, I changed the plug twice, the carb. has been changed so the odds on a fault there are now seriously high, I don't think it's the air valve into the tank as I vaguely remember originally testing without the cap on, so that leaves the fuel line. There is a high probability that Simon has been right all along, in his words a 90% probability. I will try and test for the fuel tank air valve and more fuel tomorrow and test for the fuel line next weekend. Thank you all! JC just try putting more fuel in before trying anything else. At least that will rule out one thing. Quote Link to comment Share on other sites More sharing options...
Guest Posted February 29, 2020 Share Posted February 29, 2020 Im sure you already know but its important with this type of thing to try one thing at a time. Its all to easy to do lots of jobs at once but then you never get to know which individual bit was at fault. From the video it is not electrical. It is a fuel issue, Quote Link to comment Share on other sites More sharing options...
Jean-Claude Posted March 6, 2020 Author Share Posted March 6, 2020 Hi All I tested with an open fuel cap. No change, still stalled at low/mid revs. I tested running an open fuel line from the tank to the carb. No change, still stalled at low/mid revs. I then checked the spark plug. It was running very lean. I opened the low and high jet screws a little more than 1/8th and hey presto. She's purring like a cat. Quick response to the throttle and no hesitation or stalling when changing throttle. SOLUTION: So the new carb. has fixed it for me, all-be-it the carb setting it came back with from Parajet needed working. Thanks for all the help everyone. JC Quote Link to comment Share on other sites More sharing options...
paulg18 Posted January 4, 2022 Share Posted January 4, 2022 Just wandered if you've still got this same engine and if the problem has stayed away. Quote Link to comment Share on other sites More sharing options...
Ash_R Posted May 24, 2022 Share Posted May 24, 2022 Just wanted to add an update to this thread because it's the one I came across when I was having a very similar problem with my Atom 80. In my case the engine was also nearly new, around 4 hours total time, and I had one total loss of power at altitude and then several losses of power on runup. I looked for fuel line bubbles and while there were possibly some little ones, clearing them didn't seem to make a difference. Several times when the engine died at full throttle there were absolutely no bubbles in the line. (Kyle O's suggestion of a mirror attached to the throttle body was definitely useful during all of those checks). In the end I solved my problem by enriching the mixture just a touch, the engine has been running perfectly ever since. I've been checking the spark plug colour and that looks good now too, deep coffee colour. Quote Link to comment Share on other sites More sharing options...
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