Topic: 1972 CB500 - Rebuild Project

[Puffin]

A few months ago I bought a non-running CB500 that was destined to be some sort of show piece.  I knew there was a lot of assembly and mechanical checking to be done to ensure it was road worthy, however I saw potential in it and a lot of the time consuming work in cleaning and powdercoating had already been done.

I was after something that I could turn into a hobby project and so this ticked the boxes. 

The bike came as a frame and wheels plus a load of various parts in several boxes

This is what it looked like when I got it home and had mocked up all the key components to see what I had and what I was missing...

[Puffin]

As you can see some very ''interesting" cosmetic choices were being made however these can be dealt with later.

The first job was to check the bike out fully, see if I could get it started and get a better sense of what I had got myself in for.  As the bike had not been registered since the mid 1990's I have to go through a comprehensive testing process at the testing station before they would give me the certification to get it back on the road.

Apologies if my terms are a little unusual but I'm currently living in New Zealand but I guess the process is pretty similar in most countries.

[Puffin]

The first thing I noticed was I was never going to get spark.  The old coils were both shot and the wiring harness was burnt out in the middle section.  Somebody had lovingly tried to resolve the wiring problem by wrapping the burnt section in Electrical Tape and pretending nothing had happened.

Anyways new 5ohm Dyna Coils were ordered and I set about making my own wiring harness out of whatever was salvageable and whatever I could find in the several boxes of random stuff that came with the bike.

Now it's probably worth noting that I had have never done this before so most of the time was spent staring at wiring diagrams and scratching my head....  My top-tip for this however is find yourself a very large table and break it down wire-by-wire!

[Puffin]

Whilst I was at it I cleaned up the rest of the electrical components.  The shop manuals were pretty useful here as they have all the electrical specs and detail all the tests you can do to make sure everything is working ok.

[Puffin]

The hardest part I found was matching the wiring harness to the non-CB500 switch gear I had to buy (originals were missing).  These are new Kawazaki Z1 switches which have the same functions and look pretty similar but are a third of the cost.  Luckily there is good support for these bikes as well and so a wiring diagram for the new switches was easily available.

The Honda starter switch earths at the switch whilst the Kawazaki switches earth at the starter solenoid.  Once I had the eureka moment and figured that out everything was hooked up the electric side was sorted.

My intention here is more of a resto-mod than a concourse restoration.  I'm after a reliable bike with some modern upgrades.  I love the 70's simplicity, the flashes of chrome, and the styling but I also like a modern edge and some modern upgrades.

This bike will be ridden around the country so an initial touring type set up is probably where I'm heading.... i'll probably change my mind a 100 times so it will be interested where I end up

[Puffin]

New coils & plugs.... Think I got these from Z1Enterprises?  Did some research and these were the cheapest and their international postage rates were good.

As I'm in New Zealand international postage is what's going to kill me on this project.   I'm trying to do large orders in one go but also stay under the customs radar.  My mate just had a complete Dyna coil and ignition set posted but Customs seized it and demanded $120 in import duties...!

[SOHC4 Cafe Racer Fan]

You may want to ask some of our friends in the land of OZ about who they use to source replacement parts (Terry in Australia, Retro Rocket, Dave500).

[Puffin]

Ok so Step 1 complete and I could now get Spark.  Next step to check everything working ok before I attempt the big fire up.

After setting all the points, the chain tensions, tappet clearances and everything else I read that there was another filter inside the lower crankcase so I removed the sump to make sure that was all clear...

That's when I saw the Primary chain was eating into the engine case...!  It was very loose and also appeared to be rubbing on the side of the Cam Chain tensioner which had not been installed correctly.  The bottom end of the tensioner should be sitting in a small recess cast into the engine case.  You can see in the photo it's missed it completely.

All I know about the bike is that it was an old NZ Police bike and it had been off the road since about 1994.  I can tell this because the stock dials and headlight were changed for an integrated set as the speedo's were often removed and calibrated.  You can see the different set up in my first photos.  If anybody is interested I can post a pic of  the different dial the police force used to use?

A bit of research on this forum revealed this is quite a common problem as there is no primary chain tensioner on this model.  Once it is worn you basically have to replace it and hope you were lucky enough to catch the problem before it eats through into the oil gallery.

So engine tear down then to replace the chain.  Probably a good idea anyway seeing as the old speedo was reading about 85,000 kms.

[Puffin]

You may want to ask some of our friends in the land of OZ about who they use to source replacement parts (Terry in Australia, Retro Rocket, Dave500).

Yep good tip thank you...  I've just read through MickB's CB500 rebuild thread as well.  He's another one down our neck of the woods.

[Stev-o]

Subscribed...

[Puffin]

Rocker cover and cam - all looks ok..... to me at least. 

By the way if anybody sees things differently, or something I have missed at any point please do feel free to pipe up.  I have never stripped an engine before so my knowledge is mostly based on Haynes, Clyma and Honda Manuals, Dino's Hack-a-week YouTube channel and this forum!

Cam lobes and journals within spec and no signs of excessive wear on the bearing surfaces of rocker arms.  I know the CB500's have an issue with the rocker arm rods spinning and wearing into the castings but to be honest I couldn't see much of a problem and I tried jiggling them about and didn't get any noticeable movement except for one which was extremely minor.  The holes don't appear to be lobed at all either.

I've heard you can put an extra o-ring in the end when you put the Cam side covers back on and this adds pressure to the rocker arm rods and reduces the movement?  I think when I get to the stage of rebuilding I'll do some more research and see if somebody has come up with any better preventative measures.

[Puffin]

Cylinder head removal was fairly easy.  No evidence that the rings were leaking however that pile of rust at the base of the cylinder studs means I'll defo be getting a new set of studs.

The cylinder sleeves don't show any signs of wear but I will be cleaning stuff up and measuring against the specifications to make sure.

[Puffin]

Some more pics...

[Puffin]

Here's a tip.... if you have to smash something this hard to make it function as it was designed to do then the chances are there's something wrong and your making it worse??

The clutch push rod was also snapped.

I believe these are all common CB500 clutch problems?  Luckily there are a couple of Japanese Bike Breakers around and I found a replacement rod pretty easily.  The Clutch adjuster seems easily available internationally but no luck locally yet.

[Puffin]

Once the top end and covers were off I took the lower section out and started on the studs.

The double-nut trick worked well.  These are long thin studs however and the torque bend from loosening them from the top was scary.  If I wasn't replacing them I would have probably gone and splashed out on a stud remover tool.  2 were loose, 5 were a pita, and the last one was a pure B***ard!  Even after a week soaking in WD40 it wouldn't budge.  I guess they have been in there for 45 years and had clearly been getting water to them.

Anyways I pushed my luck with the last one and even though it had started to go it eventually gave up on me........  !

[MickB]

Go puffin, hit me up if you need  something. If I can help I will, go Wallabies.

[Puffin]

Hi Mick, thanks for the offer.  I've been following your efforts with great interest.  I should probably point out that I'm actually not a Kiwi before we enter into some sort of 'Who's got the better Rugby team' debate.  As Pommie I'll just agree that you win..... usually at everything.... except maybe darts??

[Puffin]

Does anybody have an opinion on these shifter forks?  The books say the key part to check is the fork end width which all are well above the minimum thickness. 

There is clear wear happening down the base of the fork however?  I can't see how this really is a problem so unless anybody knows better I was just planning to clean them off and gently remove any burrs or rough edges.

[Puffin]

I used some Plastiguage (or Flexiguage as it's known around these parts) to test the Crankcase bearing clearances. 

For those who don't know how this works it's basically a little strip of waxy plastic that you lay over the bearings shells, insert the crank and the other side of the case and torque the bolts down as per the manufacturers specs.  The plastiguage gets squashed to a certain width and the packet has a scale printed on that tells you how much clearance is between the bearing shell and the journal.

For the CB500 the maximum you want is 0.08mm.  It looks like I have a good 0.05mm on all bearings except the outer edge of the #1 bearing where the rotor sits.  I guess the weight of this rotor may wear the outside of the bearing a little more or maybe the seal wasn't quite aligned and it didn't squash down as much?  Either way it's still ok and I think i'm going to carry on without new shells for now.

I discovered this process from Dino on his Hack-a-week CB750 YouTube series.  Well worth checking out for any other noobs out there.  He does some amazing educational videos.....  Thanks Dino... It was great to put this into practical use and you can see it worked perfectly.

[Puffin]

Some more pics

[Puffin]

So I've pretty much got myself up to speed as to where I am at the moment.  I have been meaning to start this thread for months so I have 100's of photos I've been trawling through and trying to remember what happened.

Last week I got the engine cases back from the shop where they were washed, dipped and bead blasted.  They also removed that broken cylinder stud for me as well as a couple of stripped screws that I had partially drilled out.

Before we start the debate on bead blasting.... If you don't mind I'd like to just endulge myself, and others with a similar disposition, with a string of engine-porn photos.....

[Puffin]

.... soooooo cleeeeeeaaaann

[Puffin]

... and more 

[Puffin]

With bead blasting I know some people say never do it and others say you can but make sure you are super confident all galleries etc are spotless to avoid disaster later on.  I figured that given the extent of the breakdown here I was in the perfect position to ensure everything was cleaned properly.  The shop took a lot of time cleaning and even drilled out the gallery ends to make sure they could access all areas. 

This means I now have removable plugs which grants access to some of the harder to reach places if this engine ever gets torn down again.

As well as the shop spending the time to clean I will be doing my own cleaning process as well to make extra sure.

To be honest I wasn't 100% sure this was the right thing to do but looking at my ''as new engine" now I'm pretty damn happy

[Puffin]

Ok so I think that's more than enough posts for one day...!

I've got a full Vesrah gasket kit, oil seal kit and some other goodies on the way but I still need to order the Primary Chain and a load of other goodies.

I pulled out all the wheel and steering bearings last weekend (thanks again Dino for the video on that, probably saved me hours of trial and error!) and I have a complete All-Balls set on the way.

Also sourced some brass swing arm bearings from Germany at a good price.

Cannot get Hondabond here and can't find anybody who will ship that outside of the USA so probably need to have a rethink on what to use during assembly.  Can get it in Australia but the shipping charges are criminal and I'm just not prepared to pay what the guy was asking.

Anybody got any alternatives?  There must be something with similar properties?  They do sell it on 4into1.com but currently out of stock so I might just have to be patient and wait till they get some more in.