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ROS 125 Bugger to start when hot


ParaRob
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Hi Guys,

I have a PAP ROS125 (with decompressor). She (IT!!!) tends to start quite well when cold, a prime and a couple of pulls and she's away.

BUT... If on those odd occasions (ha ha) when I have to kill the engine (wing reset etc), she (IT) envariably won't restart for usually 10 minutes or so, then voila!!!

Any thoughts on what to check / change would be greatfully received.

:explode:

Rob

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Hi Rob and welcome to the PMC. :)

I am sure you will get all sorts of answers that will lead to your problem being solved :-) We have someone local (to me) who can most likely solve it in a few mins....

Where abouts are you?

SW :D

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Hi Guys,

I have a PAP ROS125 (with decompressor). She (IT!!!) tends to start quite well when cold, a prime and a couple of pulls and she's away.

BUT... If on those odd occasions (ha ha) when I have to kill the engine (wing reset etc), she (IT) envariably won't restart for usually 10 minutes or so, then voila!!!

Any thoughts on what to check / change would be greatfully received.

:explode:

Rob

Hi Rob,

Do you mean when up in the air or on ground? I have a Ros 125..........starting from cold, prime only a couple of times and then start with throtte WIDE open, as soon as it kicks in ease off the throtte. When hot start (actually you probably do mean when-in air) then kick start with styrrup but make sure you dont depress the throttle ie leave it open......when it catches blip it and you are away.

Works everytime with me.

hope this is of help?

Mike

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Hi and welcome!

I had this problem with a motorbike i have, miles apart from a paramotor! but i found that it started great on the choke and when cold, but it overheated and would'nt start after shut down. im not sure if you have these on paramotors as i dont have one yet, but i found it was the air filter, complete guess, but could be your problem, make sure it can breath and be cooled off!

this might be completely wrong, and hoping the lads will correct me, but maybe a thought

Mike

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Hi it might be that your pop off pressure is too low , see if you can borrow a gauge to test it look at

http://www.larssletten.net/My%20stuff/w ... t-eng.html

The pop-off pressure is the pressure at which the needle valve will open thus letting the fuel to enter the metering chamber. The value of this pressure is a function of the engine, power output and other factors and it will directly affect the air-fuel mixture that the carburetor will deliver to the engine. It is true that the mixture adjustments are done by the HI and LO screws but if the pop-off pressure is too high, it can lead to fuel starvation especially at high RPM. Such a situation will cause engine overheating and possibly lead to a seizure.If the pop-off pressure is too low, the carburetor will have a flooding tendency especially at low and mid RPM. It will also cause difficulties in restarting a warm engine.

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Many thanks guys for the thoughts.

Some answers to questions raised:

The hot starting is whilst on the ground! Typically I warm the engine up, kill it, set-up, restart and go flying. If I have to abort the take-off and kill the engine, then it typically won't re-fire for 5 - 10 minutes (frustraiting)!

"Where abouts are you?" Wells - Somerset

"i found it was the air filter" - The PAP only has an empty air box, no filter.

"pop-off pressure" - Now that is something I have not checked. Thanks for the web-link.

I did service the carb last Xmas, and she ran fine for months afterwards (not many hours because of the crap weather!).

What causes the pop-off preasure to "go off"?

Rob

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