Topic: 500 big bore carb jetting

[cobrabaggs]

Hi All
I think this site is fantastic and have been coming here for a couple of years now. My question is does anyone have specs on carb jetting for a CB500 that has a 605 cc big bore kit and a mild cam.  Stock exhausts and and air cleaner.Dyne ignition and coils . Some info would be much appreciated.
Allan

[bwaller]

Try raising the needle one notch and going up two main jet sizes to get you in the ballpark. Before you do a plug chop replace the plugs.

[TwoTired]

I venture to guess that no one has your exact combination of mods, particularly with the stock airbox/filter.

Here is some theory:
Larger displacement will draw more air through the carbs and make deeper vacuum in the carb throats.  This would draw MORE fuel through the stock jets/metering devices.  To compensate, smaller metering orifices would be needed.

However, various cam grinds greatly effect carb throat pressures, too.  Without knowing the duration, lift, and overlap specs of your "mild cam", any old wild guess is reasonable.

A Dyno test would speed the jetting process immensely. Otherwise, plan on track runs and plug chops at WOT, 3/4, 1/2 throttle settings.  Most likely the idle mix can be compensated with the Idle Air screws.

Cheers,