I am looking for Suzuki 2007 C90 Boulevard battery I can't find one for FTZ 16 BS-1 12v, 18ah

SOURCE: i'm looking for battery motorcycle suzuki

the factory size battery for a C90 is YTX16-BS-1
you might also try UTX16-1.
I just bought a replacement for my 05. Got it on
ebay. shipped to me for around $80.00 including
acid.

SOURCE: where is the air filter on a 2007 c90 1500 suzuki boulevard?

The gas tank is under the seat. To get to the air filter, you have to remove the speedometer chrome cover and the upper side covers.
I can do mine in about 10 minutes. I also have a '07 with 17000 miles on it now.

SOURCE: I'm after a diagram of the Boulevard C90 original

The exhaust for the 2005 & 2007 are the same as the 2006. They all use the exact same parts and part numbers.

SOURCE: Boulevard C90 Having trouble w/keeping battery charged.

to determine that, you will need a voltmeter and a battery charger. first, put battery on level surface and check to see if the acid is at a good level, if not, you will have to get some at a parts store and refill it to level indicated on the side. fully charge the battery over night with the charger taking the battery out first. the next day, disconnect charger and write down voltage obtained from voltmeter. next, install battery on motorcycle and try to start it. if it's starts, use voltmeter to check voltage at battery while running engine, write it down. let it run a few minutes like 20 and shut it off. check voltage, if it droped, your alternator is not charging. if it's the same as when you first tested it at 12 volts, you might be good only if you had to refill it, if not, the battery is defective and must be replaced.