Topic: CB500 K1 – 1972 – Everyone’s building one, so I’ll give it a try !

[cantarauk]

The bike is completely stripped down and engine is now out so I have a base to work from.

Work on tearing the engine down will commence this weekend and going to take this very slow with loads of pictures. Never attempted something like this before so fingers crossed it will not be too a daunting experience.

The questions will be coming in thick and fast to community from here in I am sure of it. Hopefully you will all chip in with best advice and what to watch out for.

[marting100]

Welcome from Canada!
Nice project! ....following it.
Cheers!
M

[cantarauk]

Hi Marting100 welcome,

Forgot to add that I tried to get the centre stand off but the pin was stuck solid. Tried soaking the frame/stand in penetrating oil as well as acetone for a few days with no luck. Tried the heating approach again with no luck and in the end had to resort to cutting one side of the pivot and forcing the centre stand off the frame. NO damage but did take some patience and accurate cutting.

Will post photos tomorrow.

[Mace]

Make sure you take lots of pictures as you disassemble every bolt etc. That will prove invaluable for when you come to rebuild it. Oh, and don't forget to buy lots of plastic containers for you to put stuff in. That worked a treat for me.

Sent from my E2303 using Tapatalk

[cantarauk]

Hi Mace,

I sure have been taking picture every step of the way so hopefully have all I need to get it back together.

Now that I am tearing down the engine I have been doing some additional reading to gather information as what to check before putting it all back together. A question to the community what are the most important things to be checking and also what are the most common parts to be replacing.

I plan on replacing all seals, gadgets, bearings and both chains in the engine but what else should I consider ?

Also on inspection of the cylinder head the camshaft bearing surfaces seem scratched/marked/worn but at what level of worn should I worry and be looking to replace. I have attached some images so that you can gauge the level I am talking about.

Glenn

[cantarauk]

I am glad I decided to rebuild the engine as I found a chain link in the bottom of the oil pan which I am guessing is not good ?

[calj737]

I am glad I decided to rebuild the engine as I found a chain link in the bottom of the oil pan which I am guessing is not good ?

Depends. Good that you found it. Not good that its there.

[marting100]

Hi Mace,

I sure have been taking picture every step of the way so hopefully have all I need to get it back together.

Now that I am tearing down the engine I have been doing some additional reading to gather information as what to check before putting it all back together. A question to the community what are the most important things to be checking and also what are the most common parts to be replacing.

I plan on replacing all seals, gadgets, bearings and both chains in the engine but what else should I consider ?

Also on inspection of the cylinder head the camshaft bearing surfaces seem scratched/marked/worn but at what level of worn should I worry and be looking to replace. I have attached some images so that you can gauge the level I am talking about.

Glenn

Sorry, I would like to help but I have no idea since I never did a motor rebuilt. I am sure someone around had similar questioning about the camshaft bearing surfaces. You might find some answers in the "Proven Tricks & Tips / How To's - NOT for Quesions »Engine"... (for some reason the search engine does not work for me).
Good luck and keep us posted.
Cheers!
M

[cantarauk]

The past two weekends I have taken my time and the engine is now completely stripped down with some further inspection to see if I am left with anymore surprises.

What I did notice and I wanted to ask the community for some advice on is the black carbon type burn in number 2 which is present on the piston surface as well as the valves. What would usually cause this and what if anything should I be looking out for before rebuilding. See images below





Then if I could get some further advice on the bottom bearings to comment if these are still fit for purpose. Or is it best just to replace these as a matter of caution ?







After finding the a primary chain link in the engine I was expecting to find a missing link off the primary chain but alas did not. So this must mean there was attempt to do some work in the lower part of the engine at some point. What I did notice is that there is a link added to the primary chain which is broken one side and a different colour so to play it save I am going to go with new chains throughout.

I have also made a start with milling and cleaning up the top triple tree which has had some weld added in the underside so that the usual holes are not exposed. This will need some more weld and then some filing and lastly a complete cleanup.



The final update is that my seat from Benjie is complete and should be with me soon I am undecided on the colour so the current colour is just a primer for when I am decided.

[cantarauk]

Engine is starting to get a long overdue clean which is starting to show up some of the wear and tear that I may require some advice on. Through some long and hard scrubbing and stripping I have managed to get the black engine paint off which was not best is best of shape as show in the before and after photos

Before





After



Now I just want to be sure that before I send the pieces off to be vapour blasted I have any servicing/repair work done first. See the images below which is referring to the wear I mentioned. This is from the bottom case showing the crankshaft journals.







And then below shows the wear on the crankshaft which I would be interested to hear as to how I can be sure that this is still usable.





On a positive not some more parts have arrived which for now are been added to the pile.

Rear brake light



Steering bearings



And then the best one is the seat that has arrived from BCR which look great in my opinion. Still undecided on cover scheme but have narrowed the choice down.

[calj737]

My opinion, the cam and rockers need to be refurbished. You can send them into MegaCycle or WebCam and have them hard welded and reprofiled.

The crank bearings look to have suffered some oil flow loss and "would" be a good candidate for replacement in my book. Not the end of the world, but worth doing.

[cantarauk]

Hi Calj,

I am speaking with some engineering contacts here in the UK to see what is possible from a full refurbish perspective as there may be than just the head that needs some tlc. There is a lot of work that may be required and I am going to get the whole lot done at once.

Part here in the UK seem to be the problem so I may be looking to source things like shells from the US. Would you have a contact for me to approach or a preferred site. 

[calj737]

For the Megacycle cam and rocker welding, contact Mike Rieck (member here) and he can manage that for you. He's in Boston, MA. As for bearing shells, use www.davidsilverspares.co or your nearest Honda dealer.

[cantarauk]

Hi Cal,

Thanks I tried David silver spares but was not able to get shells I required at the time. I have managed to get hem though through the engineering contact that is doing all the engine work for me.

G

[cantarauk]

Hi,

Update coming real soon but in the meantime I have a question to the community about tyres for the rims I have. Currently I have 19x1.85 in the front and 18x1.85 rear which I am lead to believe was the standard size for these bikes. When I check the Avon website for suitable tyres I get the following

CB 500 K 0-2 (1972 - 1975)
Front Tyre
Roadrider
Front size:  3.25-19 54V

Rear Tyre
Roadrider
Rear size:  4.00-18 64V or 120/90-18 65V

For the rear the rim sizing when checking the specifications they are listed as:

Roadrider AM26
                            
size - 120/90-18   
load/spd index    - 65V
rec rim (in) - MT2.75   
alt rim (in) min/max   width (mm)- 2.50 - 3.00

Any suggestions ?

G

[cantarauk]

Hi,

Its been a while since I posted a update and its been a long and cold winter with very little progress.
To add to that I have been away from home working on some large projects which have taken priotity (Pays for the bills so needs must)

Progress since the last post -

The worn engine components have been sent to a motorcycle engineering company (SEP) for refurb. What they have been working on is as follows:

- Measure and replace conrod bearings
- Measure and replace crank main bearings

- Re-surface the camshaft journals in both the cylinder head and cam cover to repair wear
- Hard-weld and grind the camshaft to new cam journal profile

- Valve seats 3 angle cut
- Valves removed checked and cut to match

- There was some damage on the lower case on the points side which they are repairing

- All part will be blasted before been returned

While the engine is been worked on I have been doing odds and sods so as to move forward. The wheels have been torn down so that I could get the hubs to the blaster for a cleanup. These will then be polished and ready for rebuild.





The wheel hubs back from the blasters made a real difference but there was some damage from oxidisation and age but sanding that fit seemed to solve the issue. Will be cleaning and polishing over the next week ready for rebuild.





Bearings removed using the rail bolt method since nothing else seemed to work. I have then received new spokes and new bearings so once the polishing is done I will be ready to rebuild the wheels.









The front rim was badly rusted and had a hole in it so I ordered a used replacement since these were going to be cleaned and then powder coated. I am pleased with the outcome but still a bit undecided on using the original rim thickness on the bike or going for a little larger on the back.

[cantarauk]

Additional Update

I have been working on some mock-ups for the rear sets so that I can explain this to the guy who will be doing some welding and fabricating for me. I am going of a Kott cycles look for the rear sets and am hoping to use the original rear foot peg mounts to achieve this. Like I said it is a mock-up so bound to change. These are very rough but I hope you get the idea.

[SOHC4 Cafe Racer Fan]

I would de-burr that foot peg backing plate, or your pants or boot will get caught on it,

[cantarauk]

Not sure I will be going with that shape as I thought the same. Will use these purely for the mock-up and then get some steel laser cut mounts made up.

[cantarauk]

Been spending today polishing a few parts that are going to be require for rebuilding in the coming week. The wheel hubs are looking good and shiny and after some Mothers polish will be ready for a build.

Rear


Front


The forks lowers have also has a good polish and once the sanctions and other components arrive this week I will be putting them together.

[SOHC4 Cafe Racer Fan]

Very nice!

[Stev-o]

Very nice!

+1...love polished aluminum

[cantarauk]

The wheels have become a priority as my inexperience has caught me out.

I was working on the frame removing tabs and cleaning up where I can getting it ready so that it can be sent off to be powder coated. The next step was to figure out where all the electrics would be positioned and now most of this can be hidden in the spaces under the cowl and seat.

It was then pointed out by the guy who will be doing all the welding and fabrication that I had not worked out my clearances for the back wheel. By this time the tyres are already off and spokes cut so before I could do anymore frame/fabrication planning I had to get the wheels complete and shock dimensions worked out.

So some wheel hub polishing and wheel rims powder coated as mentioned earlier it was time to build these up. There is something to be said about lacing a wheel that is quite relaxing.









Wheel laced and then off to for truing and tensioning and also new set of rubber. I went with the Avon road-riders and rather than getting a wider rim stayed with the stock 18x1.85. Very pleased with the outcome.






Now that wheels are complete I have been speaking with the guys at Hagon to best advice what shock preferences I have based on the wheel clearances. They have advised 335mm with 20mm restriction giving me a 60mm travel. Shocks are as shown below accept with clevis option.



And now back to where I need to be working on the frame

[cantarauk]

Update -

I have been speaking with the guys at SEP and they have finally received all the bearings so now the engine work can begin. They are going to measure and fit all the bottom end bearings including the conrod bearings which should save me a job.

Then the cam was in a bad shape as shown above in the post which is going to hard welded and then machine measured to the cam journals. The journals were also very in a very bad state and will be machined repaired. They will also be looking at the rockers and if required hard weld these too.

The engineering works seems to be a tall order but I am glad to be repairing items rather than looking to replace these but and I am a bit worried about the costs but in for a penny in for a pound.

All been well these will be back with me fairly soon which will and then the engine rebuild can begin.


What I was going to ask the community is about engine painting as I seem to get mixed reviews from different sources. There seem to be people that powder coat engines with a thermal type coating and then others go with the VHT rattle cans spray job or other spay types. Not sure what is best and if not painting would be a good option. If I go with not to paint what would the general up keep be like and is there some treatment options that would be required to protect the engine ?

What is the general consensus and/or advice on this?

[calj737]

If you hard weld the cam, the rockers need to be hard welded too. The material hardness difference will eat the rocker faces very promptly.

Regarding painting/coating/not painting - Aluminum oxidizes immediately. It continues to oxidize forever and depending upon its exposure to moisture, your engine cases will turn a chalky, silvery grey. To prevent that, paint them or powder coat them. Else you will need very regular maintenance cleaning and buffing with some type of aluminum "wax". Not so hard to do if the motor is on the bench, no carbs, etc. A major pain in the arse assembled in the bike.

Paint or powder coat is perfectly fine for regular performance. The thermal coatings are typically applied to the head and jugs to assist in dissipating the heat internally and promoting cooling by the air flow around them.