Z1200 runnin 6 miles per litre..

pinging? what kind of pinging and where is it coming from?

pinging, knocking, pre-ingnition causes by either lean mixuture and/or to much compression..... just like a diesel engine

What compression is your big bore? 10.5:1? If so, what octane gas are you using. I don't think you will want to retard the spark much more than 5 degrees. If the gas mile WITH THE PINGING is OK, and the only symptom of a problem is pinging, is there a way to buy higher octane gas? If not, consider picking up a Dyna 2000 where you can vary ignition curves. Varying the ignition curve on a high performance motor using the D2K is a lot more precise than turning the points plate. Dyna gives you about four curves that retard the ignition advance and generally one of them works well. I had a Kaw Vulcan 1500 with 10.5:1 pistons and given their relatively small combustion chambers, pinging was pretty bad till the D2K was installed and the correct curve was found. I don't understand Euro or any overseas octane rating systems but here in the states we have 87, 89 and 93 (typical in TX anyway) and the Vulcan was happy using 93 Octane with the D2k but pinged badly with the stock IC igniter.

Compression is 10.5 to 1. I'm using the highest octane (ron 98)
and yes in the States they use a mix of Ron and Mon figures which is also not making any sense to me.
I just figured out last time I refueld with Ron 95.....
But going back to my qeustion would a bigger main jet or raising the needle cure the problem??

Thanks for your replies George!

The pinging? I don't think either of those things will have any effect on the pinging. Higher octane or retarding the ignition curve will... don't know of anything else unless you want to lower your compression ratio.