Topic: Do the VB44B carburetors come stock on the 1980 Honda CB650C Custom?

[verro]

It is my first project bike and I haven't been able to confirm that the carbs that came with the bike (which isn't running) are the correct/oem ones.

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-Name

[fizzlebottom]

There were no VB44B carbs that came stock on any CB650 sold in the US.

VB44A carbs came with the 1981 CB650, CB650C, and 1982 CB650
VB44C carbs came with the 1982 CB650SC Nighthawk
PD50B carbs came with all 1980 CB650 models
PD50A carbs came with all 1979 CB650 models

If you have VB44 carbs on your 1980 CB650, then you have a cylinder head from 1981.

[verro]

You say the cylinder head on it is not stock if the VB44B's are on?

[fizzlebottom]

You say the cylinder head on it is not stock if the VB44B's are on?

Correct. The only difference between the 79/80 cylinder head and the 81/82 cylinder head is the intake spacing. '81 is when they switched from PD to CV carbs, which required different spacing. So some PO of your bike wanted to change the carbs and needed to change the cylinder head as well. Hell, you might have a completely different engine like I did. Check the casting code on the left side flat part below the #4 carb and above the clutch cover. It'll say RC03 or RC05 probably. I suspect your carbs came from Canada or Europe though since no US carbs were stamped with VB44B, only VB44A and VB44C. If you do have an '81 or '82 engine, the only real difference aside from the intake spacing is that you'll have a very slightly different transmission ratio: Final reduction of 2.376, 2.314, or 2.294 instead of 2.5 or 2.438.

[verro]

Ok yeah the engine says RCO3F even though on the vin it says RCO5. So am i correct to assume that this is not the stock engine?

[Don R]

 Am I the only one that sees 44A?

[verro]

Am I the only one that sees 44A?

It lists the A on the stamp but the B has a box around it and I am assuming that that means it is the B. I could be wrong?

[fizzlebottom]

Am I the only one that sees 44A?

It lists the A on the stamp but the B has a box around it and I am assuming that that means it is the B. I could be wrong?

Yeah, they're VB44A carbs, not VB44B. That means you have press-in slow jets. Not the worst thing in the world, but not easy to clean properly. What a lot of folks do is drill them out and install screw-in jets. But only bother with this if you're having legit issues cleaning the carbs.

And about the motor, I'd bet it says RC03E, not RC03F. We might be able to figure out if its the original motor or just the later model cylinder head from the rest of the motor's serial #. RC03E-XXXXXXX. Not guaranteed, but possible.

Either way, motor parts are all the same. Nothing different at all. If you rebuild carbs, just need to get kits or parts for the 81/82 models. Yours came with #120 main jets. And you would have to use the 81/82 carb insulators, not the 79/80.

[verro]

Ok so it is RC03E-2214227. Anything you can tell from that?

[RAFster122s]

The exterior of those looks pretty rough...

Gonna need a commercial ultrasonic cleaner usually to clean up well and CV carbs and a very good aluminum safe cleaner. The PD carbs are so much less problematic...

[verro]

The exterior of those looks pretty rough...

Way more worried about getting the bike running right now. Cosmetic comes after.

[RAFster122s]

inside condition can reflect the care of the outside

[verro]

Oh I opened them up and inspected them after I purchased them and only had to clean them up.

[fizzlebottom]

Ok so it is RC03E-2214227. Anything you can tell from that?

I don't think there are any definitive sources from Honda about serial numbers, but it looks like you might have an '81 motor. Someone probably swapped both the motor and carbs from a wreck over to yours from 1980. It isn't uncommon to have part swaps like that.

Like I'd mentioned, this changes absolutely nothing about any parts you would obtain for work aside from the carbs and carb insulators.

[verro]

Thank you very much for your help!

[Don R]

 Or, your bike was built late in the year and got the updates early. Honda didn't set aside parts on a certain date and switch to the next model, they used what they had until a batch ran out then switched whenever possible. 

[fizzlebottom]

Or, your bike was built late in the year and got the updates early. Honda didn't set aside parts on a certain date and switch to the next model, they used what they had until a batch ran out then switched whenever possible.

Could be? I haven't seen every SOHC/4 CB650 built, but I haven't run across any that spanned the transition between 80 and 81. I did hear of a few '82 CB650SC Nighthawks that got the unpainted motors, but who knows? Maybe there were a few '80 models with the '81 motors.