Topic: The Gift Bike

[North Bike]

Hi All!

I was recently gifted a 1981 CB650 that is in rough shape, but I believe that it has the good bones needed to come back from the grave and I intend to see that happen! I've worked on CL200's, CB350's, and CB360's, but this is my first time with the 650 class and I'm sure that moving from 2 to 4 cylinders/carbs/etc will present me with some new learning opportunities!

The first thing I want to do is to get it back into factory spec and part of that is to get the right exhaust. Currently I have a very nice looking exhaust that came with it, but it doesn't fit. I saw a thread about exhaust's in this forum, but it didn't seem to mention the 650 model at all and I didn't want to post there till I had the right info. After looking around on the web, I've noticed that there were several variations to the 650 in the early 80's which might account for why the exhaust I have (while looking correct) doesn't fit.

When I say "doesn't fit" what I mean is this, the headers fit into the engine very nicely and the bolts line up there. The right side bolts up perfectly, but then on the left side, the pipes hit the kickstand/ mounting and are unable to bolt up in the rear. Are there any 650 experts who can tell me if there is one very specific exhaust that fits this model? Should I sell these and move to a 4-1? Advice in this area would be very welcome!

[North Bike]

Adding some Pics

[Stev-o]

First off, welcome.   I know very little about 650's as I only have 450/550/750's.

A quick search turned up the Sankei 2061 is for the CB650C  [Custom?]

http://www.sohc4.com/cb550/cb650/

What model do you have?

Here is the model guide if you need help to determine model, compare your VIN to the guide...

http://www.sohc4.com/cb550/cb650/

[North Bike]

I had looked at this but was a little confused as my SN reads JH2RC050X as opposed to the listed JH2RC0507. The rest of the numbers there make me think it's just the regular CB650 (JH2 RC050X BM203715). I don't suppose anyone can confirm if the exhaust should be 4-4 or 4-2? OR there are any recommendations for 4-1 that people like?

[rb550four]

 The 650 standard comes with spoke wheels and the custom comes with Comstars is the only way I can remember. and the 81 is the 1st year of the stock 2 rotor front brake....on the custom only. No one here has been successful  at adding an additional rotor and brake setup on a spoke 650 yet. 
  There has been some differences over the head configuration over the years . I haven't noticed any change in the frame from 80 on, but that doesn't mean that there wasn't  different mounts that were attached between  the muffler and the frame.....I haven't had all the models from all the years of chain drive 650 yet or aftermarket pipes , and the ones I do have aren't on the property right now, so I can't be sure that any of this is true or just a possibility. Have you had all the exhaust joints loose (and not just some of them ) to see if they just need to be tweaked one way or another as to not interfere with the kick stand? and do they go under the engine on that side or do they go on the outside of the frame or do they split leaving the kickstand between them?  If they are a really nice set of pipes, can you make a flat stock mounting plate that would attach to the pipes and then to the frame? ......to keep a more stock look. Headers are well ...they are just headers , and all the exhaust goes out one side leaving the other side pipeless and the center stand will be hanging out back there in plain view , all by itself , in that nakedness ,with that gigantic part that you step on to operate the center stand hanging out in the wind. Quite unattractive to my mind for one thing , but , the worst part of this center stand extention is that it is severely limiting to laying into a left hand corner with or without pipes and may require an underwear change if you survive it....ask me how I know.
  That looks like a nice machine to bring back from the grave. Does it run? How deep was the grave?

[desertrefugee]

...and the center stand will be hanging out back there in plain view , all by itself , in that nakedness ,with that gigantic part that you step on to operate the center stand hanging out in the wind. Quite unattractive to my mind for one thing , but , the worst part of this center stand extention is that it is severely limiting to laying into a left hand corner with or without pipes and may require an underwear change if you survive it....ask me how I know.

Boy do you and I agree on this! Believe it or not, I was just commenting on my disdain for centerstands in general on the naked Goldwing forum earlier this evening. Funny.

[MauiK3]

I’m afraid I like center stands, makes service easier

[rb550four]

   I like the center stand at chain lube  time and polishing time. all my bikes are always on a kickstand .
 I have taken some center stands off the bikes I get frisky with , they are easy enough to put back on when needed. I find no enjoyment or benefit once everything goes silent except for the wind in your ears as you float freely still  wondering when the last time this feeling came upon you....until the realization of the ground coming up to meet you momentarily.... that is the moment when you remember when the last time you had that feeling was.
   It's one of those things we have to remember and always adjust for while riding, but sometimes it all happens too fast to react and it's out from under you before you know it. The  4 into 4 650 pipes will treat you the same way without the center stand too. So I guess if you don't get frisky ,ever , those may be the pipes for you. But if you already know you are a balls to the walls kind of rider perhaps the 4 into 1 header (without a center stand) is what you need.

[SOHC4 Cafe Racer Fan]

Nothing a set of swingarm spools and a rear stand can't solve when you want to have the bike perfectly upright and/or the rear wheel off the ground. Just some minor drilling and tapping on the swingarm.

[North Bike]

Hey rb550four!

Thanks for the great thought starter/advice. The "grave" wasn't too deep, but there are lots of little parts missing from some previous owner who must have had project A.D.D or something.

I was able to slap the right side exhaust on and bolt it up no problem, but regardless of how loose the left side is and how much I fiddle, I've come to the conclusion that it's not gonna fit without "relocating" the kickstand mounts. The pipes come under the frame and split with ALMOST enough room to get the stands to split the pipes, but not quite.

To keep the project moving forward while I source the right exhaust, I decided to tackle the carbs next. I've finally given in and ordered an ultrasonic cleaner but in the mean time I began disassembly and evaluation. I was surprised to find metal "diaphragms" where other Honda's have had rubber in the carbs! A very interesting design, however I'm missing a slide return spring... I also noticed that the pilot and secondary jet don't have screwdriver slots to remove the jets. Anyone know how to get those out? Or maybe I should just leave them in and clean it that way?

In my excitement to disassemble, I also removed the choke plates, however when trying to screw the old screws back in, it appears the cut and flaring of the screws will require me to get new screws or risk cross threading the brass mounting shaft badly. Annoying, but not the end of the world, It appears in retrospect that it is necessary though to allow me to replace O-rings on those little "pipes" between carbs.

Anyone know of a good way to make their own or buy new T fittings for fuel lines? The ones here are 100% shot.

Also, I  found this brass piece in the bag of miss-matched carb parts that is clearly broken off in the threads. Anyone know what it's for? I couldn't find any threaded hole with the other half in it.

[North Bike]

Many long hours have been spent researching these carburetors and I've finally gotten some answers! The small brass "nozzle" is in fact a vacuum port (PN#16026460731) for the automatic petcock which mounts to the top of the carb assembly. Taking apart the automatic valve, it appears to be in good shape, so I'm going to see if I can find a replacement port of some sort and get that piece working again. Internally, I've come to the conclusion that there is only one adjustable jet in the 1981 CB650 Carbs. I don't see any damage to suggest tinkering and no possible way to access the slow and midrange jets I see in there, so I'm going to leave them and clean them the best that I can.

I also wanted to post here in case anyone is coming across the same issue that the '81 has an accelerator pump with a shorter plunger rod than everyone sells online, however, all other specs are the same, so you can just order the longer one and cut it down to match the old one.

I found some new T boots on cmsnl, but they are a little pricy. Anyone know where I could get new ones for less than $80 bucks?

Also, I'm trying my very best to do the carbs 100% right on the first try so I don't need to pull them off multiple times. The ultrasonic cleaner I just got is a part of that effort, but I was wondering, to clean all the internal passages, would you recommend that I use something stronger than simple green and water as my mixture?

[RAFster122s]

Check out South Sound Honda of Olympia Washington for stock Honda parts. Probably lowest price in nation and their shipping charges are reasonable. If Honda still has it they can get it and ship it to you. Their discount on Honda parts offsets much of the shipping charges on big orders if not offsetting it completely.
Great service and pretty good turn around on the orders.


https://www.southsoundhonda.com
https://shop.hondabikes.com

David