Help needed with which carbs for my CB650

[G9DUB]

Hi all

I after some help, I recently purchased a CB650 and it came with two sets of carbs and the owner wasn't sure which ones were the right ones.

The problem I have is the bike is registered as a 1982
Frame No. RC03-2101843
Engine No. RC03E- 2227120
From what I could find out is the frame No. is for a 1979 model and the engine No. is for a 1981/82 model. Hope your all still with me.......lol

So should it have the PD51A carbs or the later CV carbs.
I've got a set of PD51A and VB54D

Any help would be great as I'm ripping my hair out trying to find the answers.........

[Volker_P]

Welcome here!

As you have everything, the question is easy to solve. Intake spacing of piston and CV carbs is different. Due to this, there are two different cylinder heads (up to 80 / 81-on). The heads only differ by the intake spacing, heads and head parts are completely interchangeable.
So just check out which carbs line up with your engine head intakes.
Hope you also have the proper carb boots and throttle cables as they are different, too. Some small rubber hoses may also look different.

[G9DUB]

Hiya thanks for the add.......

Well the VB54s line up but I thought they should be VB44s?????? So what do the VB54s come from?????
Also I see honda do sell a 2mm offset carb insulator for the CB650 which I thought about using to try and get the PD51s working......

[Volker_P]

The French 1981-on CB650 have stock VB54 for sure.
Maybe others, too. Where are you from?

Never heard of CB650 offset boots from Honda. Would be interesting if they exist and one could still get them.
Someone proposed Kawasaki boots to fit 81/82 carbs on a 79/80 head, but this would be of course the other way round: viewtopic.php?f=4&t=722

[G9DUB]

The bike is in the UK but I don't know where it was before I had it as it was re registered in 1997 so it could be an import....????
I'll see if I can find the link it was on eBay.
Thanks.....