Topic: 81 cb650...one mismatched carb???

[nuzzi]

i just started to dig into this bike i picked up recently and noticed the second carb in (from your left leg) has a different bottom cover, it has some kind of adjustment screw on it or something, i didnt really look to far into it as i had little time, is this normal or do i need a new carb now? the tops look the same.

[Bankerdanny]

I don't know about 650's, but the #2 carb on my 550 is slightly different than the rest in that the slide does not include the adjustment screw on the top for synching that the other 3 carbs have. Other than that it is physically the same as the rest.

[JimJamerino]

 Given that your bike is an '81, you should have CV (Constant Velocity) carbs, which are somewhat different from the mechanical carbs most of us have.  As compared to the carbs on my '80 CB650, the #2 carb is the baseline for the others, and mine has an accelerator pump on the bottom of the #2.

Your first line of defense is your repair manual(s), followed by the search function here.  There's some good info in the FAQs and How-Tos, too, though info on our 650s is sometimes limited.

[OrganDonor]

The second carb should also have an accelerator pump which feeds all carbs from the #2 bowl.  The accelerator pump shows up as an extra cover with 3 screws on the inside of that carb and to the rear. 

[Frankenkit]

I thought only the 79-80 #2 carbs had the accelerator pump?

[cb650]

All the 650's have a accel pump.

[nuzzi]

thats what i assumed, thanks!