Well after a month away from the hobby to move house, look after my kids whilst my wife went to hospital and had another baby, and generally sweat it out whilst our monsoon season rapidly approaches, I have finally found the time to get back into things. I have fixed my plane after the crash and although it does not have that new look anymore at least it can fly again. The main problem I am having now is with the engine. When I get it started I start turning the mixture screw in and usually only get around half a turn in and the engine dies.(Im starting the plane with the screw 1 and a half turns open). The other problem I have is at full throttle the engine surges as if it is losing fuel. I have checked the fuel tank and bung for leaks and it seals tight and I also checkd the fuel lines but they too seem okay. Anyone have any suggestions??

Regards,

Troy P.

Welcome back troyp,open the needle valve 2 to 2 1/2 turns,start the engine,give it 3/4 to full throttle,the engine should be rich and 4 cycling,pinch the fuel line if engine speeds up,which it should then lean the engine,screw in needle valve, continue doing this until when the fuel line is pinched ,nothing happens,that is max,richen the engine so when line is pinched the engine rpm goes up 300 to 500 rpm ,after high speed is set,check low speed ,go fly

What he said... You are starting at a very lean setting.

Let us know what happens!
james

Thanks for the tip, I will give it a try. One thing though, why do you say I am starting at a very lean setting? My manual says to start with the engine 1.5 turns open for the 40 and 46la and 2.5 turns for the 65. My engine is a 40la so thats why I am only opening the screw 1.5 turns.
Also will this solve my problem of surging at high revs?

Thanks,

Troy.

Hi troyp,I have a drawer full of manuals and on page 16 of the copyright 1999 OS manual that is exactly what it states. I try to start all engines on the rich side if the needle valve is not set correctly so as not to overheat or damage the engine,if you can start the engine then use the pinch test and go from there.

Troy...the needle valve assembly is probably the least precision made part of the whole engine so what's given in any manual is only a guide. Remember that an engine will start and run even if it's way too rich but if it's too lean then it'll likely just fire up then stop. It also depends on what fuel you're using. Lots of nitro (not usually a problem in Oz ) means the needle has to be opened more than with low nitro so I've never understood these suggestions about "open the needle 1 1/2 turns" without it even being said with what fuel!

Hi troyp,did you get the engine running good?

gday John,
I must admit I havent had a chance to give it another go yet as I had a few things on this week after work. I hope to give it a try on Saturday sometime. I'll keep you posted.

Thanks,

Troy.

Troyp: The engine surges because it revs up and burns all the fuel in the crankcase. Then when it sags the fuel has time to build up in the case until it picks up and burns it out starting the cycle all over again. You can leave the heater on and run a really rich engine, but a lean one won't run without fuel. Better to start a little rich and set it than to try to set the needle exactly. I always open my engine a few clicks then lean it out. This is just my starting routine. Some engines will keep a setting for a long time. I've read about people who set it in the spring and don't change it for months. Also unless a plane is really underpowered, I don't lean it out trying to get the last few rpm out of it. This gives me some room for the mixture to vary a little without making any difference in performance and avoids a lean run.

Thanks EC121, thats one of the best explanations I have heard.
I took my plane to a mate who runs a small engine shop (lawn mowers etc) and he helped me to set it up so it runs right and showed me how to do it. One tip he did give me which works great was to use a squirt of aerostart to get the engine to fire. He said it will not harm the engine and it works great especially because I do not have an electric starter and have to use a chicken stick. The enigne fires after the first flick of the prop.

Regards,

Troy.

To start a two stroke by hand I put my finger over the carb then turn it to pull the fuel up. If you do this with the heater on it, the engine will kick back(while you have a good grip on the prop). when the mixture is right. When you feel this kick, get your chicken stick and flip it. The starting fluid will work, but it is also something to have to keep track of. I forget enough things already. Just for fun I sometimes start my four strokes by flipping the prop backwards. If I get a good prime, the engine will backfire when flipped. Since I am flipping it in reverse, the backfire starts the motor!! If it doesn't start right away or burns the prime out, I go ahead and use the electric persuader. :-) One fellow in our club starts his 4S by spinning the spinner backwards by hand. Just a little flip and it starts idling.