OK you got me! What is a weedibix???   If your interest can be peaked,there is a topic "tuneing your intake" on 6-30-16 that dove into this very science. I can't speak for others but I learned a lot.

Now it's my turn. What's 6-30-16?

Course

It's best to use a K&N air filter or stock. Then troubleshoot the carburetor. Take a method approach. First open the carb and see what size jets are in it. Main and pilot. Then talk to Lancer about a upjet kit probably 2 to 4 sizes up from what's in there now. Also do the needle valve washer mod with 1 or 2 washers. It's going to be trial and error but you can get the jets and needle out with the carb in the engine. Just pull the fuel tank off for opening the top of the carb. And don't drop any screws.

That's it! Good luck and no real magic is needed.  

Well I went to 6-30-16 and clicked on the link. Thought I'd been directed to some science boffin site! The intricacies of the 4S ICE are very obviously so complicated when it comes down to getting the utmost from an engine. All I really got from it was that the wind likes to have a bit of a journey before it gets to the carb. Sadly this isn't going to happen on my bike. I will try lifting the needle first, and then consider upping the main jet. All I really want is a motor that's happy at all throttle settings, not really looking for a drag strip killer.

Tried that. Doesn't fit. :'(