OK, here's hoping I get this right in my first post. I'm trying to get the jetting right on my 2000 model FC501 Husaberg. I had a 41mm FCR lying around and thought I'd give it a run on the berger. After a few hiccups I managed to find a needle that seems to work, these carbs have a massive range of them and it's too expensive to buy a bunch to try. I'm using the accessory richer needle from the 426 Yam. Its an OBDVS. With ELF Atmo Rally race fuel I'm running a 190 main , 52 pilot and the needle in the 2nd from bottom notch. The thing is running OK but when I tried 3rd notch from bottom it developed a huge mid-range flat spot. So I figure I need to maybe try a richer needle. Question is do I stay with the same length/taper etc. To work this out I really need to know if the leanness is across the throttle range or only in the middle. So here's the query. Is there a way of doing mixture readings by checking the plug colour at other than full throttle openings?