Microlighters

Hi fellow aviators

I'm a motorized paraglider pilot, flying a Simonini G24 based rig on the Highveld. I've had 125 trouble free hours on the motor, but now appear to be lacking on power at WOT. Jetting has never been changed, but I have leaned out the mixture recently by dropping the needle to the lowest position. This helped for a while, but once again the motor is not getting to max revs (Manufacturer states 7300rpm, I'm seeing around 6200). I'm suspecting wear of the needle or needle jet - But maybe I'm way off track. One thing I did change was the fuel lines - Could this possibly have an impact?

Does anyone know where I might locally find spares for this carb, or perhaps even a new carb itself??

Or maybe where else I should be looking??

Cheers

Roz.

Have you checked if there might be another reason for drop in rpm? Always treat a sudden change in your engine performance with caution. There is a reason for it. The jetting will not change all of a sudden, it will be a gradual thing over time. I have read somewhere that the jet wear is about 4 % on 350 hours. Those needles are supposed to last about 300 hours. Check for Leaking/worn carb rubbers, maybe the heads need a re-torque etc etc. See the engine manual for details.

Comet Aviation supplies should have a overhaul kit for the carb, just check your jet sizes. http://www.cometaviationsupplies.co.za/

I agree jets and needles last quite a long time. it sounds to me like youre exhaust could be carboned up . If this is the case and I might be wrong no amount of jetting tuning tourqueing etc will fix youre problem , could you perhaps borrow a pipe from a motor that is running fine and try it? Most people laugh at my next question (normally moto x riders) Do you understand 2 stroke fuel mixtures ie 30 to 1 . 50 to 1 etc suprisingly most people dont so much so that dirt and quad magazine aked me to write an article on this for them. lets take 32 to 1 , most people assume 32ml of 2 stroke oil to 1 litre of petrol Wrong! firstly how the hell do you measure the 2ml ? The correct way is 32litres of petrol to one litre 2stroke oil the one is always one litre of twostroke oil and the 30 ,32 ,40, 50 etc is litres of petrol , so if for example you were to run 40 to 1 and were mixing oil into ten litres of fuel you would put 250ml of oil in, twenty litres of fuel at 40 to 1 =500ml and finaly 40 litres of fuel=1 litre 2 stroke oil. I apologise if you do know this and im not insinuating that you dont , someone else that reads this however might not , and it might help them. It might also have absolutely nothing to do with the current problem, just a thought,,,

http://www.csgnetwork.com/oilfuelcalc.html

The above web site make it easy,

Roz be very careful weakening mixtures on a 2 stroke or your asking for an engine seizure...the petrol charge helps cool the piston and you know what the oil does...weakening the mix and you piston will run hotter expand more and can become tight in the bore...with less oil due to a weak mix to lube it,

What made you think it was running rich???

The plug colour is a good indication of the fuel mix.

Nick.