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Carburettor tuning


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So, my motor is all re-built and working. (yay)

I've adjusted the carburettor and it all starts beautifully. (double yay)

I've let the engine warm up and run it to full power. It accelerates without hesitation but isn't quite getting up to full speed. (Hmmm)

I've read and re-read the manual. It says to adjust the main needle until you get to peak revs and then adjust it back a little to make the mixture slightly richer so you don't seize the engine. Well that seems simple enough... except...

I've adjusted the main needle from one end of its travel to the other and it makes not a single jot of difference. The motor seems to be running too rich whatever I change. It even has a cheeky little back fire when I turn it off. (not so happy now)

Have any of you two stroke experts out there got any ideas? The engine is a Radne Raket 120 ES with a Walbro WG10 carb.

I've spent all weekend tweaking and fettling. I did get a small flight (20 yards in length and 15 feet off the ground) but it just isn't developing enough thrust to climb out. :-(



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I'm sure the WG10 is pretty similair to the WG8, and that means the needle you are turning is the low speed mixture setting so won't make any difference to the high end mixture as it has a fixed high rpm jet (non adjustable).

On mine I had to bend the meter lever to richen the mixture, you may need to do the opposite - google WG8 tuning :).

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I done the same on my wg8 carb and realised there is no needle for top end its a fixed jet inside the carb.

The cone shaped needle is for idle and the other is for low to mid mixture.(if its the same as mine?) 1.5 turns from closed, i remember the Rad i had before being 1.75 turns from closed.

I had my pop off pressure sorted to get things right which you need a tool for which is what Dan suggested but it is very sensitive!

Huury up its gonna be good all week!!!!!!!!!!!

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I had a similar issue on the Walbro 32.

even though the 32 had a hig end et the problem was that even if you closed it completly it was still running too rich.

It turned out the the the pop off presure was wrong and was allowing way too much fuel in.

Adjusted the spring and it was a lot better, I am not sure if you have a pop off spring on that carb but I would get it checked.

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