Topic: '82 CB650 never got no love...till now!

[ViscerallyChallenged]

Hey there! so this website has been a WEALTH of information and help, thank you much motorcycle sages!

Anyway on to the bits!

I recently bought my first motorcycle a 1982 Honda CB650 standard US

picked it off from a previous manager/now friend for a sweet 200$, and he even threw in a helmet that cost as much as the bike did for me!

10k miles
it Was not running

He said he ran it for a little while, however it choked on the freeway one day for him and he decided to try some repair work of his own!

I'm not sure what he did exactly, but from what he's explained and what I found out, I'm more sure than he is about what he did.

Starting with the obvious, he cleaned and repainted the gas tank a solid black, and replaced the gas tank lock

The solenoid had also been replaced, apparently in a vain attempt to solve the lack of power problem

Apparently he couldnt "get the cables" to reach correctly after installing the solenoid

and the relay to starter motor cable was damaged, as the insulation was scraped off.

going with a tape-shrink-tape method as replacing the entire cable seems unnecessary because the strands are in tact and the cable wont be recieving constant load

Next issue, a fried wire, that is to be assumed why he "stopped messing with the thing" when he couldnt get the battery installed correctly

According to helpful advice on this forum, and a careful analysis of the wire diagrams

He must have wired the battery backwards and he fried the Clutch Switch Diode otherwise known by part name Silicon rectifier diode


Next on the list of my rebuild...
THE CARBS

I have been told they were leaking, which was my first hint at fuel system problems for that freeway death!

Breaking them down, I realized I do not have a manual available with the Keihin style carbs my bike has. Again back to using the parts inventory to give myself a little more room to see what's going on

the common service manual combined with a parts catalogue  filled in a lot of the blanks for me!

I have a disc type carb without a diaphragm. I dont really know what type of carb I actually have, but I now know the only diaphram these have is in the throttle or something pump under carb number two.

Anyway I have a basic rebuild kit, and Thankfully I ordered it because MANZ these jets were in TERRIBLE CONDITION

even if they are salvage it's not worth the cleaning for me

three main jets/slow jet? whatever were covered in orange crust and took some force to break loose and even had to dig a little into the crust flush with the screw head bevel

these things may never have been taken apart

curiously enough, only one gasket was actually cracked!

the idle screws at the bottom of the bowls were crusted in, and the springs didnt release until sprayed out with carb cleaner

Oh and here's a tickler, not a single jet had an o-ring come out with it. actually I found maybe two o rings in total across the assembly that weren't on the drain screws

And now we are up to my most recent hiccup

after figuring out that these carbs have a drain specifically to remove the assembly  (thank YouTube and common service manual)

that explained the orange buildup at the bottom of the bowls

crack loose the rusty drain plugs

every single one is perfectly shiny new UNTIL

the tip, which looks literally as if you were to make a bullet projectile out of the most porous rust, and put it in a brass casing.

so the threading and o-rings are doing just fine

but it is amazing how precise of a line that tip is just rusted out(back to never been taken apart in its lifetime)

so now I'm waiting to order a set of drain screws to replace those and finish the cleaning process

would LOVE to seperate the assembly and put these into a soda blaster and get them sparkling again. in between each unit it is so crusty and filthy and their just isnt much I can effectively do even on the surfaces I can reach

Their is a plastic kidney shaped piece inside the cap side of the carbs that I have yet been able to identify or find direct literature thereof. it has a notched leg that enters the groove of the piston(?) and the only thing troublesome for me is they all have this paper gasket underneath and #$%* all if I'm getting it new. otherwise I'm clueless to this armature and I will be replacing it as it was



FURTHER TROUBLES AND CONCERNS

1-no choke cable, definitely psyched to hold my hand in the middle of my engine assembly until the idle holds

2-i have no idea what other problems the electrical has in store

3-odometer was reported as not functioning, speedometer device at wheel seems suspicious too but tachometer seems possibly legit at engine

4-definitely needs a new chain and grease, possibly new sprockets. cant find what size chain to get. chain illiteracy is a growing problem these days

5. after rolling off a flat bed ramp, the front brake seems to have seized. To no surprise  their doesnt seem to be any brake fluid either. The reservoir seems like it's ready to move on so I will let it take the cable with it and hope my pistons arent warped and fresh fluid will change the attitude

6)I have no idea or any excited interest in changing the front brakes, and I'm even less amused by entertaining the idea the rear brake is actually a brake. the manual tells me its simpler but I'm not buying it.

7.Its covered in cracked rusted chrome

8.I am a little isolated and without another vehicle, with very basic tools

All in all, the manuals leave you a little blind, but they do all seem to work on the same principles, just in some oddly different approaches

I'm really excited to get this thing together again

I would love to do a full restore and bring her further than she was out of the factory

but currently I just want/need to get this thing at a safe operating condition, and worry about investing after it gets me to places that make my pockets deeper

I've gone a little crazy with the knowledge cram and motorcycle mechanic crash course

but it's been really enjoyable despite the hangups and frustrations

and while I feel like every step I take I find a lot more ahead

I'm glad I'm not taking steps backwards and actually making headway at diagnosing problems, and solving them correctly!

without further ado

PHOTO DUMP

pretty much a quick photo overview of the work I've dug into, and some of the reference shots I've made for putting the carbs back together

definitely took out a few more pieces than my rebuild kit can replace

but I think the only pertinent replacement I dont have is the drain screws, check out that last image to see EXACTLY why these things were dripping gasoline (according to last owner)

let me say also it's amazing that everything electrical wise accumulatively can be replaced for at or below 600$

I want to run these carbs into pieces before spending 1200$ on fresh brand new carbs thoo







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[Bankerdanny]

Your carbs are Constant Velocity (CV) carbs. The throttle moves the butterflies to control the flow of air into the carb. The movement of air creates a vacuum that raises the slide and its needle rather than the throttle cable like all other SOHC4's.

Cleaning the stock brass is very much worth the effort unless you got genuine Honda carb kits with actual Keihin jets. The brass in the aftermarket kits are notorious for not being the size they say they are and for needles not having the same profile as stock.

A guitar string (the e-string) is very useful for cleaning out clogged jets without damaging the inside.

The plastic kidney shaped thing in the carb is the float. It controls the flow of fuel in the carb. As the fuel level in the bowl falls the float sinks allowing a needle to drop and fuel to enter through a small port. When the fuel rises to the correct level the float rises also and pushes the needle up and into the hole, closing the flow of fuel.

The photo with the screw driver pointing at the square piece of brass is pointing at part of the accelerator pump, which is located in the space ship looking part of the carb with the shaft sticking out of it. When you open the throttle quickly part of the throttle arm pushes the shaft squirting fuel into one of the cylinders.

If your master cylinder is pumping fluid use it to push out the brake piston so that you can clean out the caliper. Replacing the piston seal is probably worth doing, but not always necessary.

[ViscerallyChallenged]

Your carbs are Constant Velocity (CV) carbs. The throttle moves the butterflies to control the flow of air into the carb. The movement of air creates a vacuum that raises the slide and its needle rather than the throttle cable like all other SOHC4's.

Cleaning the stock brass is very much worth the effort unless you got genuine Honda carb kits with actual Keihin jets. The brass in the aftermarket kits are notorious for not being the size they say they are and for needles not having the same profile as stock.

A guitar string (the e-string) is very useful for cleaning out clogged jets without damaging the inside.

The plastic kidney shaped thing in the carb is the float. It controls the flow of fuel in the carb. As the fuel level in the bowl falls the float sinks allowing a needle to drop and fuel to enter through a small port. When the fuel rises to the correct level the float rises also and pushes the needle up and into the hole, closing the flow of fuel.

The photo with the screw driver pointing at the square piece of brass is pointing at part of the accelerator pump, which is located in the space ship looking part of the carb with the shaft sticking out of it. When you open the throttle quickly part of the throttle arm pushes the shaft squirting fuel into one of the cylinders.

If your master cylinder is pumping fluid use it to push out the brake piston so that you can clean out the caliper. Replacing the piston seal is probably worth doing, but not always necessary.

what I'm talking about absolutely is not the float and is not on the float bowl end

believe me I am well aware of every piece that goes to this bike that has a name

the only thing I've found (not that I'm looking heavily

is that it's part of the "packing set"

as well in the diagram the section shown pointing at a square  is not described  in the assembly only the throttle pump

I'm pretty familiar with all this

but here is the photo specifically of the "kidney shape" that is on the piston(top side) NOT THE FLOAT SIDE

I thought I was clear when I said kidney shaped plastic piece with a channel that matches with the piston slide, on the piston side not the float side

so he is a pic of the channel

and the plastic piece in question that I am not sure how to replace the now orange paper gasket

ordering the packing set from CMSNL would  include all the screws for the full assembly  as well as the "packing set" and o rings

my only issue I'm having so far with the carbs is knowing where all these extra o rings go!

literally nothing had an o-ring but the delrin cap covering the main needle in the throttle slide piston

I have a very general concept of where most of the O-rings might go, but again some parts are kind of leaving me blind

Other than being a CV style it is also diaphramless with a concentric float system

this is important because the piston/slide/entire top half of the carb is different than anything in the manuals I have available

either way the only reason the carbs arent back together is because I need to wait on the drain screws for the float bowl

which by the by isnt described on the parts catalogue the way you would normally find it

also back to the photos, I believe this piece is part of the slow jet? as it was described in the common service manual that the slow jet is not removable it is press fit




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[ViscerallyChallenged]

Again the common service manual is my best reference.

All of the SOHC4 engines to my knowledge are Constant velocity

however the specific type of carb my bike possesses is identified/described as an intermediate system with disc throttle valve and diaphragmless vacuum piston

I'll admit i am a little overwhelmed in describing it all accurately

 I believe this retainer cover has something to do with the atmospheric pressure relief as well as retaining the position of the vacuum piston

it is never specifically described to my knowledge

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[Hutch]

O-rings:
Fuel rail
Air mixture screws
Float bowl drain screws
Float bowl #2 accel pump

This will help http://honda-cb750-s.456789.n3.nabble.com/file/n4046333/Honda_Carb_Manual_revD.pdf

[Gublonge]

The link Hutch provided is a MUST HAVE Manual. These units-being operated by air pressure rather than a mechanical slide-in my experience can be quite finicky sometimes if some of the passageways are gunked-up. All of the various pressure differentials and vacuums and such.

I recall still reusing the paper thingies, since I haven't found a source..

The gaskets, springs, washers etc. with the adjustment screw will occasionally disappear

I have a laminated copy of that carb rebuild manual: The CV carbs have the potential to require constant attention, especially if you can't find the good fuel. (but that's a different story)

A thorough rebuilt works wonders, but careful breaking the carb bank if you don't have balancing equipment for the rebuild....
 

[Hutch]

The link Hutch provided is a MUST HAVE Manual. These units-being operated by air pressure rather than a mechanical slide-in my experience can be quite finicky sometimes if some of the passageways are gunked-up. All of the various pressure differentials and vacuums and such.

Not everything in the manual applies, don't short cut the cleaning.  I no longer favor a soak in pinesol or simple green. A soak in Berrymans followed by cleaning with a guitar string and compressed air works great.  I didn't bother removing any pressed in jets.  I highly recommend removing the vacuum assisted petcock.  Try this for cleaning the accelerator pump jets if necessary.

http://forums.sohc4.net/index.php?topic=91557.0

Far and away for me the most difficult is mating the bank of carbs back together.