1979 cb650 resto-mod

620dark

You can always get it running with time or money.
Thanks for the luck and the link - I'll be sure to use that.

Of course, now that I've rebuilt the forks, mounted a new tire, and am overhauling the stock brakes, I don't want to spend money on a replacement front end :) Too many options!
 

interceptor

Member
Ha. I know what you mean. I'm trying to keep my bike stock but I'm always thinking of how I can modify it. Then I hit myself in the nuts and tell
myself to cut it out and just get the damn thing on the road. ;)
 

620dark

You can always get it running with time or money.
I feel that if a part fails and a better/newer replacement is available, then I should consider "upgrading." Car's clutch wears out? Time for a lightened flywheel and a stronger clutch! Bike's clutch springs are worn? Time to put in 10% stiffer springs! :D

However, I try (try being the operative word here) to get any vehicle, car or bike, running well stock before I start messing with things. I'm not sure where I'm at with this bike, however :) It seems like every time I get it moving under its own power, I end up tearing into something else and it becomes immobile again. Someone's going to end up with a very thoroughly sorted bike when I'm done with it, however.
 

620dark

You can always get it running with time or money.
After getting the incorrect set in the mail, I finally received the proper K and L brake master cylinder rebuild kit, and used it to overhaul the gummy master cylinder.

For reference, here's a picture of the order that the pieces go - you will probably be able to figure it out like I did, but I'm such a nice guy that I'll save you the effort:



The piston was snapped in half. Oops.



Also, as you clean out the master cylinder casting, make sure that you open BOTH of the holes that lead from the reservoir to the cylinder bore. In this picture, you can see the larger fluid hole on the left, and the smaller bleed hole on the right. You may have to use a very small drill bit (I used a PCB board dill bit) or a piece of sharpened guitar string to open up the smaller hole, as mine was stuck tight with old brake fluid.



Voila, a working reassembled master cylinder. I replaced the o ring that seals the reservoir to the casting, but chose not to spend the $60 for a new reservoir as even though mine is ugly, it is solid.

 

620dark

You can always get it running with time or money.
Welp, I pulled the carb needle shims, thinking I had fixed the idle issues that had been plaguing me.

I guess I should have not been surprised it idled like crap and had to have the throttle tickled to stay running until I turned the idle knob in big time.

After much head scratching and thinking, I came to the conclusion that the slow jets must be the issue - the bike has plenty mid range and up top when it is running almost exclusively on the main jets, but idles for crap, takes forever to warm up, and tends to stall when the clutch is let out. Rather than drop $22 + $13 in shipping :eek: for a set of new #35 slow jets (the press in jets are a real PITA to find), I opted to order up a $13 pin vise and drill bit set. A #80 drill bit is 0.3429 mm, which is pretty darn close to the 0.35 mm hole diameter of a #35 Keihin slow jet.

I carefully started to "drill" through the slow jet, and was surprised to dislodge crusty crap. It appears all the slow jets were reduced to almost half their diameter by crap. I had soaked these jets in old school carb cleaner, and then in the Pine Sol dip of doom, cleaned them out with copper wire, and there was still crap hanging on in them. Gah!

Next step is to reassemble the carbs and try again. Hopefully I'll get a decent cold and hot idle out of the bike now.

Also, the master cylinder reservoir is leaking. The plastic of the reservoir is shrunken with age, and will not seal right. Rather than spend $60+ on a new reservoir kit, I opted for this ebay find:

http://www.ebay.com/itm/150814486315

$27 shipped for a brand new master with an integral reservoir. I will be sure to let you folks know how good it is when it gets here. The old master, leaking and all, felt great with the rebuild kit in it and the braided stainless steel line. Anyone want to buy a rebuild brake master with a leaky reservoir to further fund this madness? :)
 

620dark

You can always get it running with time or money.
Yup, cleaning out the slow jets with a drill bit did it. Of course, now I have to readjust the choke idle speed, because with the choke out it wants to idle at 6k RPMs. Oops.

With the cleaned slow jets and the 110 mains it is running great, but a bit rich. As an experiment, I pulled the air filter and opened up the air box some. Still runs and revs well, so I'm thinking velocity stacks. Everyone loves velocity stacks right? The stock air box plenum is distorted by heat or time or general bloody mindedness, and it keeps pulling the rubber boots off of the intakes for the carbs, which does me no favors in getting this thing tuned.

Has anyone put something like foam over velocity stacks to keep more than just small birds out of the motor? Velocity stacks are great and everything, but I would like to avoid doing a Cucamonga rebore on a bike with only 8,000 miles.
 

620dark

You can always get it running with time or money.
After getting some input from forum members, I decided to try to repair the stock intake system. I bought a good used air box off of ebay, and seeing it makes me really understand how messed up the one that came with the bike was. Hopefully that will help with tuning, as I know that intake air leaks on any vehicle can cause issues.



The new box isn't as "mushy" as the old one either - it actually feels like hard plastic. More news after the box is installed!
 

620dark

You can always get it running with time or money.
So, what started out being a quick removal of the air filter housing / rear fender in order to install a replacement carb -> filter housing air box turned into removing the swing arm and all the ancillary bits, cleaning off 33 years worth of oily mud and muddy oil, and then priming and painting lots of the bike.

Spoilers; eventually I did install the replacement air box.

In this page from the service manual you can see how the air intake system works. My biggest issue was that what is labeled the air cleaner chamber was melted and smashed in where it joins with the air filter housing / rear fender. I was able to find a good replacement on ebay, and it was immediately obvious that the one on the bike was a mess.



However, to do it right, I felt that I needed to remove the air filter housing / rear fender. To do this, I needed to disconnect the shocks and lift the back end of the bike in the air to give myself enough room to remove the housing. Of course, there were about 1,000 other pieces that had to come out first, like the battery and the rear chrome fender.

Once I had the air filter housing out, I discovered that the crankcase ventilation hoses were hooked up to the wrong spots on the air filter housing. Huh, having the valve cover vent going into the wrong spot can't help anything, and no wonder I never got any water out of the condensation trap drain!

At this point, I was feeling saucy, so I decided to partially strip down the bike and get some paint on the frame. It was a beautiful sunny day, not too hot, perfect for painting. I removed the rear wheel and then pulled the swing arm. The next step was cleaning 33 years of grunge off the swing arm and rear wheel, and cleaning 33 years of chain lube out of the drive sprocket housing on the side of the transmission. The chain, a non O-ring unit from DiD, got a dip along with the sprockets in some 87 octane. The swing arm and the sprocket cover ended up in there too, as there was a lot of crud caked onto those parts.





The engine and center stand were cleaned on the bike, and really shined up nicely. I took the wire wheel to the swing arm to get some loose paint and surface rust off of it, and then wiped it down with acetone. I hit it with three coats of self etching primer, and then with two coats of satin black. It ended up looking sharp!



I also cleaned several areas on the bike where there was surface rust, and hit them with the self etching primer and the satin black. There was no bad rust on the bike, only some surface rust from being outside. Someone took care of this bike at one point, but it had become neglected in its later life.




After the paint had dried, everything had to go back together, starting with the swing arm and rear wheel. I lubed the swing arm bushing while it was off the bike, as the zerk fitting is hard to get at on the underside of the swing arm. Everything went back together well, except I discovered that the right hand exhaust mount was bent, causing it to foul the swing arm at full droop. I straightened that out, touched up the paint on the swing arm, and finished that up.





Now I could actually install the new air cleaner chamber, along with the air filter housing / rear fender. Everything went back together nicely, and for the first time since I've had the bike, the carb boots slid right into place. I reinstalled the plastics, seat, and tank, and had a bike again!

After some fiddling, the bike fired right up without the choke. Hmm. It is running pretty rich, which is about right since the 90 main jets have been replaced with 110s, and the air box is now leak free and almost all stock, with the exception of the air filter cover being missing. I think I'll try 95s or 100s and see if the bike stops fogging for mosquitos.

 

620dark

You can always get it running with time or money.
Woo, read over 1000 times!

The new master cylinder is Bethpage, NY as of today, so hopefully it should be at my door soon. I'll be comfortable with putting paint on the tank when I no longer have a brake master gently sprinkling the tank with brake fluid. On the plus side, there is a lot less paint to strip...
 

CHOPPERRICK

New Member
Looks like you"ve got a good start it! It's nice to see another CB650, They're very rare in my area. Everyone thinks it a 750. I just sold mine(with many tears :'() after 18 years of working on it. Here's a few pics of how it finally turned out.
 

Attachments

620dark

You can always get it running with time or money.
That is a hot bike! If you miss yours, you can always buy mine when I'm done with it, muhahahah!
 

CHOPPERRICK

New Member
Thanks for the offer, but you know what they say, you can never go back! I'm now in the process of tearing apart a pristine '84 Goldwing Aspencade with all the bells and whistles. Not sure how far I can go, buts it's fun getting there! And it's just as much fun watching the looks of the Goldwing guys when they see it!! You know, Honda never offered the Goldwing in flat black?????
 

620dark

You can always get it running with time or money.
Oh man, I've seen some very hot minimalistic Goldwings. Do you have a build thread up here? I think they look very cool stripped down - they have a very sleek look for such a large bike, and the flat motor is very visually interesting. Good luck with that one!
 

620dark

You can always get it running with time or money.
The brake master cylinder arrived today from China. It was advertised as for a '90s CB400, but should work well with the single disk setup on the CB650. The quality of the part seems ok - the finish isn't perfect, but the action is smooth.

Without further ado:

Website name provided without comment


The integral reservoir lid should prevent leaking


I may replace the Allen screws with stock 10 mm hex heads. Note the integral sight glass - it is actually glass!


It came with a new brake light switch as well, which is a nice touch


Not sure if I'm going to paint it black or leave it silver. I'll have to see how it looks on the bike.
 

620dark

You can always get it running with time or money.
The master cylinder bolted right up, and best of all, doesn't leak! :D

I swapped the #90 main jets back in, and balanced the carbs using my trusty $2 vinyl tubing and ATF tool plus some motion pro 5 mm carb sync tubes.

However, what made the biggest improvement was upgrading the ignition system. I tried my homebrew GM HEI system again, but that still wasn't working right. So, I tried using the GM coil packs with the stock Honda ignitors. Surprisingly, that worked great! I was worried the increased current draw of the new coils would overheat the ignitors, but they didn't even get warm.

I take no responsibility for you cooking your bike with my half assed upgrades, however :)
 

620dark

You can always get it running with time or money.
Now that the bike is running well, I've moved back to the cosmetics, as the bike is far from pretty even with a shiny frame.

I started by replacing the torn seat cover with a new reproduction from David Silver Spares UK for a little less than $40 shipped. I couldn't do better than $60 or $70 in the States, so I was pleased and amused to do better buying a part that had to cross the Atlantic to get to me.

http://www.davidsilverspares.co.uk/CB650Z/part_29115/

The cover was a little short in the rear, but some stretching and the cover provided by the chrome trim strip made it look fine. I suspect the UK model CB650Z has a slightly different seat than the US model. Replacement was otherwise straightforward and really cleaned up the look of the bike.

Next it was on to paint. The tank was covered in peeling black over bad primer over what was left of the original paint, all half eaten by brake fluid leaking from the original brake master cylinder. Nasty. At least there was less paint for me to remove :)

I had some old school paint stripper gel - I think it's probably illegal now. It eventually dissolved extra thick Nitrile gloves, and let me tell you, I knew when I got a little bit on me. It worked great on the four layers of paint on the tank though!



The tank was is great shape underneath the nasty paint. I hit it with the wire wheel to clean up a couple of rusty spots where the paint had been scraped off, but that was about it.



Next, self etching primer, wet sanding, and more self etching primer, and more wet sanding. I love this stuff. It sticks like hell to bare metal and makes a nice hard basecoat.



Finally, time for color. This is a GM color - a dark metallic red. Lots of light coats, wet sanding, more light coats, and then two heavy coats. I'm giving it time to let it really set up, then I will wet sand it again and clear coat it. The pictures doesn't do it justice - the color looks almost sinister it's so dark red.





I also cleaned up the side covers the best I could - the stickers would not come off. So, I used a high build primer with lots of heavy coats to smooth them out. The side covers had some cracks in them that I had fixed with epoxy, so the heavy primer also helped fill those in too. After I wet sand them I will shoot them with color too. I might try to find reproduction stickers for the panels, but I'm not sure anyone made them for this one year wonder :)

 

620dark

You can always get it running with time or money.
I also rebuilt the petcock with a new gasket from Sirius Consolidated Inc. off of ebay. I drilled out the rivets, hammered flat the bent retaining plate (how the hell did this get bent!?!?!?), and replaced the gasket and the seal where the petcock attaches to the tank. Two new rivets, and it was back up and running!



Now I need to find a replacement for the missing left side Honda tank badge, and I think the bike will be about done!
 

YogiBear

New Member
A new paint job does so much for a bike. Can't wait for some high res pics with the clear finished :)...... About the petcock, is it the same style as the dohc 750s?
 

620dark

You can always get it running with time or money.
YogiBear said:
A new paint job does so much for a bike. Can't wait for some high res pics with the clear finished :)...... About the petcock, is it the same style as the dohc 750s?
Lol, I'd have to get a better camera than my phone then, but thanks. I will share pictures when it is finished.

This is the petcock it has:



It appears it is the same as at least the '79 DOHC CB750. $65 new on ebay, yikes! It does not have the vacuum operated petcock shutoff, however. I don't miss it - those have left me at the side of the road in the past, once on a Nighthawk with a dying charging system, making it the only reason I didn't get home. I was not amused.
 

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