Motorcycle Repair: V-Starr 1100ccc exhaust-carburetor, air fuel mixture, v twins

Question
Recently installed pair of Cobra Slach-cut mufflers for my 07 V-Star 1100. had a mechanic install recommended Cobra jets. I noticed slight power increase and also noticable smell of gasoline. I could never find the source. I went on a road trip of about 400 miles and into the second hour noticed a lage brown band forming arount the muffler. But only the top muffler, no discoloration on the bottom one. When I got to the halkway point I noticed the top pipe was black with exhaust soot, but the bottom pipe was like out o the box, all shinny and new. Also My mileage dropped 15-20 MPG. My mechanic says that just the way it is and that all V Twins have this happen, but several folks at bike shops think the problem is simply that the rear carb is running way too rich. Whose side are you on?

Answer
Hi Skeezy,

I will say that the rear cylinder runs hotter than the front cylinder, however with that said, it will need more fuel to run correctly and if anything it'll run more lean due to the heat (rear cyl wont see as much moving air as the front one) My guess is what your local mechanic did was just increase the air/fuel mixture screw, which is NOT the proper way in re-jet a bike to increase fuel flow to the carbs alone. Did he give you your old jets back after the re-jet? If not he more than likely didnt do the re-jet and what he did was not the way it should be done, not to mention is dishonest. I know of techs who do this to make the extra money without the actual expense...
  When a re-jet job is done (unless this is a rocket which its not) Is to ONLY bump up the PILOT jets 1 size bigger, leave the MAIN jets alone, turn the fuel/air mix screws out to 2.5 turns and install a .30 shim under the main jet needle.

I have done MANY carbs jet jobs, and know to be fact this works perfect for your application.

Tell them you'd like this done, and I guarantee this will give you the results you seek..

Hope this helps!!

~Mark Panka