Topic: 1981 CB650: 1st Time Project for 1st Time Rider

[JetLifePaperPlanes]

Hey all

New to motorcycles and new to the forums! I recently took a motorcycle safety course and received my M license (I had been browsing for a used  Honda SOHC motorcycle long before then) and have just purchased a 1981 CB650 Standard for my first bike!

The good news is I got it for $500. The bad news is it isn't street ready/ride able yet. Apparently he got it with intentions of making a cafe racer but never had the time or $$$ to so it has been sitting for some time. The PO started it up and got it running but said it was not able to idle or run without the choke off because the carbs did not have any boots on them, however he did still have the boots themselves! The front brake has absolutely zero resistance when squeezed so I suspect it needs to be bled and cleaned or maybe even have the master cylinder replaced/rebuilt. The only other noticeable repairs/replacements were the tires, some serious rust on one of the mufflers(although the PO included another set of pipe with the bike) and the gas tank could use a good cleaning. I am hopeful that with these and just a few other minor repair and replacements I can get the bike street ready before the riding season is over!

TO-DO LIST

Clean Gas Tank
Attach Carb Boots (Possibly Clean Carbs?)
Replace Air Filter
Fix Front Brake
New Rubber and Tires Balanced
Install 2nd Set of Exhaust Pipes (Possibly Replace With 4-1 Exhaust)
Replace Spark Plugs
Replace Oil Filter/Change Oil


As I said I am new to motorcycles (both riding and the mechanical aspect of it) but I have 5+ years of experience with Honda B-series car engines so not all concepts are that foreign to me. I would like to do as much of the repair/work on my own that being said  I have a few questions to ask of you, if you don't mind of course.

- What are common problems on these old bike that I'll need to check and fix? and how would I go about checking/fixing them?
- What are MUST DO things I have to do to the bike before I start riding it?
- I have the bike's workshop manual, are there any other manual books I should need?
- I really wanna clean up the bike, and although it seems there aren't many major fixes there are a lot of minor ones! Where/how would you recommend I start? 

I plan on updating this thread as the project progresses. My plan is to give it a little bit more of a cafe/brat look but my 1st goal is to get the bike up and running correctly before I make any modifications! I am picking up the bike on Thursday I will post more pictures then feel free to post/comment!
 

[MoMo]

Welcome..  If the bike was sitting(and it sounds like it was) there is no possibly clean the carbs.  It is mandatory.  If you don't have a manual usually one can be downloaded from this forum.  Ask questions there is a wealth of knowledge here...Larry

[tomkimberly]

Welcome..  If the bike was sitting(and it sounds like it was) there is no possibly clean the carbs.  It is mandatory.  If you don't have a manual usually one can be downloaded from this forum.  Ask questions there is a wealth of knowledge here...Larry

+1, clean the carbs.

And if the tires are old, replace them.


Tom

[davesee]

it sounds like you have a good handle on it. give the carbs a good cleaning, and consider lining the fuel tank with an epoxy like caswell. this will help you keep your carbs clean.

you can order the rebuild kit for the master brake cylinder at partsnmore or right from your honda dealer. you might as well replace the inner and outer brake piston seals. bleeding the brakes on these can be a pain, but you might get lucky.

you may want to boil the carb boots in water or a wintergreen mixture to soften them up before installing them.

once you have your list accomplished of things you know you need to do, give the bike the 3000 mile tune up from your manual, and that will give you the opportunity to see if everything is ship shape.

best of luck, and we're here to help.

[Bankerdanny]

Welcome.

I think your instincts are good.

Pull the carbs and give them a good cleaning and replace the various internal gaskets and o-rings. I would not spend the $$ to get carb kits with replacement jets and needles as it is highly unlikely (not impossible, but very unlikely) that those need replacing and there have been quality issues on non-OEM jets and needles. Remove all the removable jets and spray cleaner through evey possible orifice to make sure that nothing is blocked. I also recommend hitting up a local guitar shop for some scrap E string. It's great for helping unclog jets.

When removing and installing the carbs, heat is your friend. A basic hair dryer blowing on the carb to manifold rubbers will soften them to get the carbs on and off more easily. A very light film of lithium grease will help get them back on.

Regarding the front brake: I would start with bleeding to see if you can get it to hold good pressure and if the caliper releases when you release the lever. If it functions properly when bled, doesn't leak, and doesn't lose pressure then I would let it be. If any part of the system doesn't work properly, then start with the caliper and work backwards to the master cylinder.

Before you try and start it, cahnge the oil and filter, check the condition of the plugs, adjust the valves, and  check your points for condition and gap (if you have points, I know the 650 went to electronic at some point).

Before you take it on more than a test ride confirm the age and condition of the tires and replace as necessary.

Be prepared to replace the fork seals. On my last two bikes they intitially seemed fine, but after a few rides started to leak.

[MiGhost]

but my 1st goal is to get the bike up and running correctly before I make any modifications!

That is probably the best plan that I have heard from a 1st time owner yet!!

Start out by taking pics of every part of the bike to build yourself a photo diary. When the time comes that you have trouble remembering how a part was installed, or a cable was attached. You will be able to look at the pics to help figure it out.

As you have already gotten a lot of good info. I will focus a bit on some of the trouble spots.

First off. The electrical system on the bike should be gone over completely to make sure that there are no problems with loose, or corroded connections. Any bike that has been sitting long enough for the tires to become questionable has sat long enough for the electrical connections to become questionable also.

The charging system is one of the biggest trouble spots on the 650. This is usually cause by the harness connections becoming loose, dirty, and corroded. The most common result is that the rotor goes bad, and takes the reg/rec with it. Make sure you clean out the carbon dust buildup from the alternator, and check the parts for correct readings.

The problem with the carbs sounds more like the slow/pilot circuit is dirty. This will be the pressed in slow jet on the CV carb, and must be taken out to be cleaned properly. There is a method for removing that slow jet posted here somewhere. I am unable to locate it at the moment. It involves using a screw, and nut to pull the jet up out of the hole that it is recessed in. 

When you have the new tires installed. Have the spokes check for proper tightness also.

One final thought. The cruiser styling of the 650 is tough to work with to get the cafe image from. The frame was changed in the '80 models to allow the drop in the seat. This makes it hard to get that clean, straight line of the tank and seat for the cafe. You might want to look into it more before getting to far involved.

[JetLifePaperPlanes]

Hey Again!

Picked up the bike today and got to work removing the gas tank and carbs, I plan on cleaning both f them this weekend. The carbs came off fairly easily(except for the throttle cables) and they did not seem to be attached securely to the air filter intake side so I am crossing my fingers that with just some minor fix ups and cleaning the bike will be up and running soon!

I plan on cleaning the tank with CLR and Klean Strip Phosphoric Prep and Etch cleaner, will I need to remove the petcock? Any tips/tricks to really clean out this bad boy out? As far as the carbs go I have been watching this Motorcycle Mikuni CV Carburetor Cleaning for Suzuki, Honda, Yamaha Tutorial as well as reading the workshop repair manual to become more familiar with the carbs before I take them apart to clean. Any problematic areas I should know about or special tools I might need for hard to reach places?

Here are some more pictures feel free to comment/post if you see anything worth noting or having any tips/info!

http://www.flickr.com/photos/101367027@N04/

[JetLifePaperPlanes]

UPDATE


Took apart the carbs today to get them cleaned and inspected. They appear to be a Keihin VB 44A carb set from what I've been able to identify... Took out the slides/needles and removed the carb bowls for cleaning as well as the main jet and needle jet but the slow jet does not appear to be removable? Surprisingly the carbs weren't that dirty to begin with but they certainly look good now! Overall they were in good shape, however there are a few screws that are stripped or mashed that need replacing and the fuel overflow "T" hoses that connect carbs 1-2 and 3-4 were ripped up pretty good. How should I go about replacing these T hoses?


Gas tank was initially soaked in CLR which took off almost all the rust, soaking in a Etch and Sketch Phosphoric cleaner overnight will rinse out with water/baking soda to neutralize it. What are some way to emulsify the water from the tank?

http://www.flickr.com/photos/101367027@N04/

[tomkimberly]

You can still purchase those from Honda, P/N 16036-460-771 and 16047-460-771


Tom

[grasscutter]

<<<I plan on cleaning the tank with CLR and Klean Strip Phosphoric Prep and Etch cleaner, will I need to remove the petcock? Any tips/tricks to really clean out this bad boy out?>>>

This is a waaaay better choice than Lining the tank.  Haven't seen pics of the tanks interior, but highly doubtful its got flaky rust.  Surface rust or flash rust, will NOT plug carbs.  Install a small inline filter for insurance.

[tomkimberly]

Yes, remove the petcock, CLR will dissolve it.

Tom

[JetLifePaperPlanes]

UPDATE:

The T joints have finally arrived I've replaced the air filter, oil filter, spark plugs (with correct spacing)! Doesn't look like I will be able to replace the T joints without taking the carbs apart individually, in doing so does this mean the carbs would need to be synced? Any help/advice would be appreciated!

[cb650]

UPDATE:

The T joints have finally arrived I've replaced the air filter, oil filter, spark plugs (with correct spacing)! Doesn't look like I will be able to replace the T joints without taking the carbs apart individually, in doing so does this mean the carbs would need to be synced? Any help/advice would be appreciated!

If you only take the outers off and are carefull not to mix up parts (do one side at a time) and only do the minimal no.   Good time to replace a few other o rings though if they are leaking any.

[JetLifePaperPlanes]

Update:

Got the carb back on the bike and everything looks good except for one hose I can't figure out... The hose in question is on the inside carb (from the right side of the bike) and is horizontal to the other hoses in the picture... Any help or info would be appreciated!

[cb650]

That is just a vent for the vacuum shut off.  Just hangs down.    .should have eliminated it all together.

[RAFster122s]

I am afraid you may need to pull the carbs again to get the slow jet emulsifier tube out to clean it. My CX500 has a model of the CV carbs and they are a real pita to remove. The carbs will develop a white scale as well as other deposits in the jets. The best way to pull the jet is to tap the top of the jet for a 4-40 screw and then pull the jet with a nut being lowered on the screw. If it pulls the jet all is good. If it doesn't, then you will need to use a excellent quality ezout made by SnapOn or Matco, nothing else here as a broken EzOut can turn the carb into junk.
One of mine came out without a problem using a Craftsman(Crapsman) ezout, the other broke the ezout and I had to buy another pair of carbs.
Need to tap it for about 3/16-1/4 inch at most...
The jet holes should be chased with a numbered drill to remove any deposits, you don't want to see any brass chasing the hole with a pin vise holding the bit.
Adding additional emulsion holes can improve fuel economy and any flatspots on the 550, not sure if 650 needs this.

Run some SeaFoam in your gas regularly, it really helps.

[JetLifePaperPlanes]

Also since the carbs do not have gas in them after being cleaned is there a way to prime them or should the carbs fill up with gas automatically when hooked back up to the fuel line/petcock?

[cb650]

With the "auto shut off"  wont prime till engine cranks.  If you have good compression and if it works.

[JetLifePaperPlanes]

Gas goes past the fuel cut off valve but not into the actual carbs... What would be the next step in diagnosing the cause?

[cb650]

Petcock or vacuum (auto) shut off?       Floats or needle valve stuck?