Motorcycle Repair: Aftermartket exhaust systems, shadow vt1100c, head pipes

Question
I am having poor fuel consumption with Jardine exhuast sytem on my 86' Honda Shadow VT1100C twin. Used to get between 140 and 150 miles on a tank. Now I get 110 to 120 miles on a tank. The exhaust sytem is the Jardine slip-on slash cut pipes. Head pipes are stock. It came with a Dyno-jet jet kit. It includes 144 main jets, (140 is stock) their own adj.jet-needle in the 2nd position from top, (stock is non-adj.) And self tuning the idle mixture screws about 3 turns out. I also have an aftermatket "Uni" foam air filter. No K&N filter is made for this bike. It runs great, idles good but gets terrible milage. My thinking is that the needles are too aggressive since that is where I spend most of the throttle time. (at cruising speed).  Any suggestions?
Thanks.
Lorin

Answer
Hi Lorin,

The engine is breather easier now with the performance parts installed. Poorer fuel economy is the result performance improvements.

I agree and as you suspect, you may restore some of the lost milage by tuning the Jet Needle. You'll have to test and tune to find out.

I find that drop in jet kits get the air-fuel mixtures close, though always need additional tuning. There's too many environmental variables shore to shore to have a drop in kit for all with no tuning.

If you want my carburetor tuning files, send me your email address as requested.

Respectfully,
Mark Shively