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Carb cleaning manual

Posted: Mon May 08, 2017 10:25 am
by Folsoml
When you first bring home your new (to you) CB650, the carbs will almost certainly need to be cleaned. This link is to a manual on cleaning the VB style carbs--like the ones that will be on your 1981 or later CB650, CB650C, or CB650SC Nighthawk.

http://www.cb750c.com/publicdocs/SeanG/ ... l_revG.pdf

This manual is actually for the DOHC style carbs like those on the CB750C, but the techniques you will use are the same.

Unfortunately, the 1979 and 1980 CB650's had PB51 carbs--which are completely different from the one shown in the manual. The manual will not help.

Re: Carb cleaning manual

Posted: Wed Jun 14, 2017 6:39 am
by fatk1d1980
This will save someone a lot of time! Thanks for posting this.

Re: Carb cleaning manual

Posted: Thu Jul 13, 2017 4:37 am
by Hutch1
Can anyone confirm if the fastener sizes listed on p. 6 of the manual apply to a 1982 CB650SC? From the manual, these are the recommended replacements:

 Qty 8 3mm x .5 x 6mm socket button-head screws (for the choke plates)
 Qty 12 4mm x .7 x 16mm socket-head screws (bowl screws)
 Qty 11 4mm x .7 x 10mm socket-head screws (air cut covers and accel pump cover)
 Qty 16 5mm x .8 x 16mm socket-head screws (top caps and rear frame)
 Qty 8 6mm x 1.0 x 12mm socket-head screws (front frame)
 Qty 23 4mm split washers
 Qty 16 5mm split washers
 Qty 8 6mm split washers

Re: Carb cleaning manual

Posted: Thu Jul 13, 2017 7:18 am
by Folsoml
Hutch1 wrote:Can anyone confirm if the fastener sizes listed on p. 6 of the manual apply to a 1982 CB650SC? From the manual, these are the recommended replacements:


 Qty 11 4mm x .7 x 10mm socket-head screws (air cut covers and accel pump cover)



All of them apply with the exception of this one. Your carbs do not have air cuts, so you only need three of these. Also, since you don't need eight of these, you can get by with 8 fewer of the 4mm split washers.

If you are ordering the set from SeanG (the author of the manual), you can get the complete set for $20 shipped, so you might as well have extras. The O-ring kits he sells will also work on your carbs.

Re: Carb cleaning manual

Posted: Thu Jul 13, 2017 1:08 pm
by Hutch1
Thanks Folsom, I just placed the order.

Re: Carb cleaning manual

Posted: Wed Jul 19, 2017 7:08 pm
by Hutch1
Can anyone tell me if the pictures below are part #16038-422-004 SCREW SET D? I see that the part is obsolete, and I'm missing one of the 4 screws? The overall length is approximately .8mm and the head diameter is approximately .7mm.

How can I determine the size screw and type of thread, I'd like to find a replacement at boltdepot.com.

Re: Carb cleaning manual

Posted: Thu Jul 20, 2017 5:32 am
by Folsoml
Hutch1 wrote: The overall length is approximately .8mm and the head diameter is approximately .7mm.



I would double-check these measurements. Less than a millimeter is pretty tiny.

Those screws cover the holes where you would connect a vacuum sync tool. Did you order the complete bolt kit discussed earlier in this thread? I would try those screws to see if one matches the thread. You will then know the size you need, and can just adjust for length.