Low gas mileage, semi-rough idle, any suggestions?

[Big Bandit]

I have had my 98 Bandit 1200s for about a year.  When I got it, it got 45-50mpg.  The past couple of months that has dropped to 30-35 mpg.  Bike is mechanically stock.  It had 10K on it when I bought it and just rolled over 17K last week.  I can smell gas when idling and she idles semi-rough.  Still runs great otherwise.  I don't see gas leaking anywhere.  No black smoke while idling.  Any suggestions?

[Bob Holland]

tune up, including carbs, float levels, sync, and good cleaning

[rider123]

Try cleaning your air filter it's probably due which would make it a bit rich, hence low gas milage.

[Big Bandit]

I just installed a K&N filter about 1,000 MIles ago along with new plugs and a valve adjustment.  I am guessing bholland is right and the carbs need a good cleaning and adjustment.  I have rebuilt car carburetors back in the day, but the fact that there are four of them, I find intimidating and I have never synced carbs before.  I stopped by a bike shop today and they want $250 to clean and sync them.  Is that reasonable?

[jeepskate99]

I just installed a K&N filter about 1,000 MIles ago along with new plugs and a valve adjustment.  I am guessing bholland is right and the carbs need a good cleaning and adjustment.  I have rebuilt car carburetors back in the day, but the fact that there are four of them, I find intimidating and I have never synced carbs before.  I stopped by a bike shop today and they want $250 to clean and sync them.  Is that reasonable?

Syncing is easy.  Once you get the vacuum caps off and put on some extenders.

[Red01]

Your K&N filter isn't over-oiled, is it? That'll cause a rich condition, too.

[Daytona]

The other day i started figuring to the tee (on handy cell phone calculator) my mpg's! 37.7 per 1 dino gal $2.44 Lots of stuff go into this! Chain can be a factor, next to tire pressure! As long as it running great like a bandit should.. Now like that over powered car we all remember when we were bullet proof young, Romp it and you got to pay!!! I lubed my 20+k mile zvm chain real good, made sure tires were where they should be for me, the bike is running great, went from34 to 37 per.. But keeping it under 120 and not getting there as fast made the biggest diff! 75mph maybe 80 with responsible starts got me back into the 44+ range!!!  Like I said its back to getting lousy miles again!!!   DARN!!!  


Hey Jeepskate99   Just curious, what do you mean extenders

[Daytona]

I have had my 98 Bandit 1200s for about a year.  When I got it, it got 45-50mpg.  The past couple of months that has dropped to 30-35 mpg.  Bike is mechanically stock.  It had 10K on it when I bought it and just rolled over 17K last week.  I can smell gas when idling and she idles semi-rough.  Still runs great otherwise.  I don't see gas leaking anywhere.  No black smoke while idling.  Any suggestions?

Hey i see you have the best taste in bikes! Got questions? i have been thru most of em. Carb sinc made very simple, carb problems, been thru a few, give a shout if you want. My bike has almost 40k and runs great. Just not as good as i want on mpg! same thing as you mpg went down here of late with $ increase. Winter mix i think! Try some sea foam in the tank. from auto store in the can! Adj needed to your primary screws and the carb sinc/ for the gas smell @ idle. Save the $250.00 the shop won't get you the education this will if you do it yourself! $250 can buy alot of gas if its running ok! I would put it towards a zvm chain! you will need it if yours is still the stock one! $123.00 item  

[Banned it.]

I would check emulsion tubes , see if the hole is round or worn oval. If oval will run rich down low. My 98 B12 had dropped to 37 imperial mpg, replaced tubes adjusted needles and now back around 45 mpg.