Topic: Some 650 questions

[Scott S]

 I just picked up a 650 engine for future transplant into my CB500. I'm pretty ignorant about the 650 and have been doing a lot of research and reading.
 
A) I tried joining the HondaCB650 forums but haven't been approved by the mods yet...

 B) The engine I picked up is # RCO3E 2302422. Can anyone tell me what year it is?

C)  It came with two partial sets of CV carbs. I thought maybe I could make one good set, but they have two different #'s on them: VE 54A and VE 65A. Are the parts interchangeable at all?

 D) I still need to check out the charging system, but someone has started changing the rotor. There's a spare in the box, as well as the ignitors. The seller told me he bought this bike for the regulator/rectifier, so I know that's missing.
 When searching Motogrid, it appears that only one year used the ignitors. Can someone educate me a little on the ignition system on these engines and what it would take to make it work in my 500?

 That's it for now, but I'm sure I'll have more questions soon.

[kslrr]

The difference in the carbs could be: slide profile, needle tapper, jets......I believe all years of the 650's used igniters......I have an '81 bike with a '79 engine as well as a spare '81 engine and CV carbs.  I'll check the engine numbers and carbs numbers tomorrow (Tues) when I stop by the storage lockers.  I might also have a reg and rect.

[Scott S]

 Is there anything special about that reg/rect. or will the ones that are now on my CB500 work?

[kslrr]

I'm not sure if the regulator off the 500 would work.  The alternators are different.

[geminimotors]

a question thats come to my mind lately, is how much of the 500/550 charging and ignition stuff transfers directly to the 650 engine?

[trueblue]

http://forums.sohc4.net/index.php?topic=40414.0

Most of your questions will be answered in the above thread.  The reg/rec unit off the DOHC 750 will work on the 650, you just need to change the plug.  The ignitors are easy to get a hold of, last I knew Dave Silvers was selling them new.  The ignitors were used on all years of the SOHC 650.  I think they also were used on the DOHC 750, but I'm not sure of this.  The ignition on these bikes is fairly simple, they still run a mechanical advance, essentially they have an electronic set of points in them.  The charge rotor off most of the DOHC engines fits the 650.  Also one more thing to note, if the ignitors have black goop oozing out the back of them it doesn't mean they are no good.  I have a pair on my bike that have had the goop oozed out all over them since I bought the bike over 2 years ago and they are still working fine.  I have been told that it is caused by leaving the key turned on for too long without running the engine.  It overheats the modules and melts the goop.

[Scott S]

 I've read the hybrid post before. I'm not really combining the two engines. I hope to drop in the 650 engine as a complete unit.

 It's funny you mention the black goop, as it's oozing out of the ignitors that came in my box of parts. Is there a test for these?
 The rest of the charging system is there, except for the reg/rect. I still need to test everything if I ever get off of overtime at work.

 I'm also unsure about the carbs clearing the petcock. I have a lead on some PD series carbs. I've seen pics of the CV carbs and it looks like they clear the petcock, but I'mnot certain.

[onepieceatatime]

Also one more thing to note, if the ignitors have black goop oozing out the back of them it doesn't mean they are no good.  I have a pair on my bike that have had the goop oozed out all over them since I bought the bike over 2 years ago and they are still working fine.  I have been told that it is caused by leaving the key turned on for too long without running the engine.  It overheats the modules and melts the goop.

I have had the goop run out of a set that was sitting on the shelf in the garage. They can be refilled with a 2 part epoxy such as JB weld.

[trueblue]

The carbs aren't interchangeable, the port spacing was changed to accommodate the CV carbs.  The CV carbs are also huge in comparison to the PD carbs.  The CV carb head from 1-2 and 3-4 is 65mm, in between 2-3 it is 92mm.  The PD carb head the measurements for 1-2 and 3-4 are 76mm, and 2-3 is 81mm. These measurements are centre to centre .  Here is a picture of a set of CV carbs against a PD head. 







The main reason I included the link is it outlines most of the bits that can be interchanged between the engines.  Also the reason I mentioned about the black goop is because nearly every ignitor for these bikes has it oozing out.  I have never bothered to refill mine, they work just fine.  I have only ever seen one go bad.  The only way I know of to test them is to hook them up and see if they fire the coils, if they do, they work, if not, they're junk.  They either work or they don't.  The charge rotor on these bikes are becoming a common issue, but don't forget they are 30 years old now.  On my 650Z the rotor shorted out and fried the reg/rec unit, a common issue.  The rotor should read (off the top of my head) 5 Ohms, if it is in good shape.  You can make the charging system off the 550 fit the 650, but the 650 system pumps out a lot more power and isn't as unreliable as the reputation it has earned.  The main thing to remember is the rotor is 30 years old and the insulation in it is getting weak.  I bought an exchange rotor that had been rewound for my 650 rather than get one that appears in good shape but is still 30 years old.

[kslrr]

My '79 engine is '2020144 and my '81 is '2223201.  Looks like you have at least an '81.  Also, engines after '79 do not have OHC 650 on the rocker covers.  The tote where my CV carbs are is buried.  I'll dig it out tomorrow and check the carb body numbers.

[Scott S]

 So, if I have an '81 I'm stuck with the CV carbs unless I change the head?

[kslrr]

Correct.  I believe there are threads on swapping the heads.