New member, new project

[scott s]

Hello all. New to HondaCB650.com and to the 650 engine in general, but I've been in the SOHC4 world for a few years now.

I currently have the SOHC4's:
- a '78 550K with ported an dpolished head, CB650 cam, 1.00mm overbore, jetted carbs and a Jardine 4-1.
- a '75 CB550 frame with a 500 engine. This was my "Sweep the Floor" bike, built from leftover parts.

...and a '72 CB500 with (currently) a CB550 engine. This is what bring me to this forum.
Before, after it sat in a barn for 28 years.

After:


I just picked up a CB650 engine and am planning on transplanting it into the '72. I've been doing lots of reading and research but still have a lot to learn about the 650.

The engine number is RC03E 2302422. I'm told that this is at least an '81, but would like some clarification on this.

It came with two partial sets of CV carbs. They're marked VE 54A and VE 65A. I believe the 54A are the correct carbs, right?
Is it also true that, if this IS indeed an '81 or '82 engine, I must use CV carbs with the port spacing on the head?

I'm sure I'll have some questions about the charging and ignition system. I still need to test it all out and see what I have and what works.
Thanks in advance, and I look forward to getting to know you guys and gals!

[onepieceatatime]

Welcome. I followed your sweep the floor build.
The VB44A is the correct for the 81 cb650, VB44C for 82. They are interchangeable, but the 44C had removable slow jets, the 44A had press in.
The head port spacing is different on the '79 and '80 than the '81 and '82, so you have to use the CV carbs or one of the options listed in these threads
http://www.hondacb650.com/viewtopic.php?f=4&t=722
http://www.hondacb650.com/viewtopic.php?f=4&t=6553

There is a lot of good information, sorted by topic, thanks to our moderator Volker, here:
http://www.hondacb650.com/viewtopic.php?f=8&t=3064

I have some 44a parts and might have a '79 or '80 head if you wanted to swap to the PD carbs. Let me know and I'll sort through the parts if you are interested.

*edited to correct part numbers*

[scott s]

Thanks for the reply. I have a lead on a complete set of carbs and boots from an '81. Any reason they wouldn't work OK?

[scott s]

I've yet to copositively ID what I have, but I think the engine is from an '82. I also believe it was from the Nighthawk SC model. Someone please correct me if I'm wrong.

I wrote down the VIN from the frame it was in, but this was all in a pile of parts and I can't be sure that the engine and frame were "born" together.

Frame VIN: JH2RC05 09CM302378
Engine # : RCO3E 2302422

I'm almost positive that's a "3" and not an 8 in the engine #.

[Volker_P]

Welcome here, Scott!

Great work on the 500!

If the CV carbs fit, it is at least 1981, Engine number starts RC03E.

If the engine number starts RC08, the engine should be black and it would be from a 1982 Nighthawk. Note that 1983 Nighthawk is DOHC, completely different (RC13 I believe).

Earlier (79/80) engines also start RC03E, however intake port spacing is different for the PD carbs. Heads are a simple swap.

I have a lead on a complete set of carbs and boots from an '81. Any reason they wouldn't work OK?

They would fit 1981/1982 engines but no idea if you get this into a 500 frame just like that.

I am a bit irritated about your CV carb numbers.
For the CB650 I know VA44, VB44, VA54, VB54(France)
So VE54 should be a version of CB650 carbs for some country.

RC08E engines only appeared in RC08 frames (1982 Nighthawk).
All other engines are RC03E, regardless of frame numbers RC03 (Z-Model 79-83, '79 US) or RC05 (80-82 US standard and all Custom).
There is no RC05E engine at all (although engine covers are visually a bit different for all engines placed into a RC05 frame), but RG01E would be a police version engine. I hope I completed confusion...

[scott s]

Well, I have an RC05 frame and RCo3 engine. The engine is black, but it's obvious that someone has spary painted it.

I also measured to spigot spacing on the head and it's certainly a CV carb engine.

[onepieceatatime]

I am a bit irritated about your CV carb numbers.
For the CB650 I know VA44, VB44, VA54, VB54(France)
So VE54 should be a version of CB650 carbs for some country.

Thank you for the correction Volker.
I should have been typing 44. I corrected the above post.

[scott s]

OK, so I have carbs that are NOT from a '79-82 SOHC 650 and what is most likely an '81 engine.

Right?

[onepieceatatime]

Here is some other useful carb info.
http://www.motorcycleproject.com/motorcycle/text/specs.html

[scott s]

Wow...the carbs I have aren't on that list at all!
I have some CV carbs from an '81 lined up.

I was planning on using the stock 4-2 headers and some shorty mufflers, but then realized why there was that odd dent in one pipe. There's no way they would work with the 500 kickstand and still look good. Oh, well....a 4-1 isn't so bad.

[scott s]

New question: Are the valve cover gaskets different?

Motogrid states "GASKET, CYLINDER COVER | Use up to Engine SN 2206140" on the 1981 model, but it lists the same # for all models.

Oh, and the more research I do, the more confident I am that I have a 1981 engine and frame frome a standard model.

[Folsoml]

The serial number is visible on the right side of the engine just above the clutch cover. I know I ordered a gasket kit once that was for a "1981 CB650" and the cylinder head cover gasket did not fit. It did not specify an engine series.

[scott s]

That's why I'm confused. As listed above, my engine starts with 230XXX.
But when looking at part #'s on Motogrid, it lists the same # for the valve cover gasket for '81 and '82, even though it has that warning.

[Folsoml]

As listed above, my engine starts with 230XXX.

I should have read the whole thread, sorry. I've used Powersports Plus before, and they list three different part numbers.

http://www.powersportsplus.com/parts/search/Honda/Motorcycle/1981/CB650+A/CYLINDER+HEAD+COVER/parts.html

[Volker_P]

For the gasket between cylinder head cover and cylinder head (camshaft level) I just used an "O-ring" 1240 x 3.5mm (cemented from 3.5mm rubber cord) because the original part they sold me had a poor surface.

The rocker cover gaskets are interchageable, although the outer rocker covers look different for '79 and Z-models. There you need four additional special bolts with rubber gaskets also at the outer covers like the two for the center cover.