What is a pretty average # for gas mileage on a stock B20b engine with twin SU's with the stock cam I believe. I don't think I've ever seen it go much more than 210 miles on 45 liters, and that was mostly highway miles. I've always tried to keep the idle at around 900 rpm. I've looked at my spark plugs a few times now and they are usually tan or grey in appearance, which is normal..yet I still get poor gas mileage! The last time I noticed that the #2 and #3 plugs had a bit of oil on them, which may indicate worn rings. I've done the valve adjustment too (set between .020-.022 as it says in the manual) I think I'm going to buy new jets for the carbs and try to install them myself as at least one of the existing jets appears to be a bit out of round. The needles definitely had some wear but apparently if my plugs aren't black the issue shouldn't be with the carbs.
I've also had my mechanic check my timing and he got it to 10 degrees BTDC at 900 rpm. I had to advance it a bit from there to try to get it to pull a bit stronger in the lower RPM's. I currently run bosch electronic ignition that came off a 75 240.

Thanks in advance for any light you may be able to shed