Topic: Cb500 Street "Race" bike refresh

[Korven]

Hello! Been around the forum for about a year, not made much posts but really like the knowledge and the members that hang around here. Starting up this thread for my project, a 1975 CB 500. To collect any questions that i might have instead of starting alot of threads. Im the second owner on this bike, the first owner had it sitting in his garage since -88 and hasnt been outside (atleast not alot) since then. checked the papers, last time it passed automotive inspection was -86. So the Thought is to freshen up the bike while still preserving it in time. Motor had a engine noise that turned out to be a valve seat that was unproperly seated. the engine is being fully rehauled atm. This is my first time doing an engine rehaul by myself but i've assisted on another cb500 engine last winter. Alot of progress has already been done and ill bring you up to speed. I didnt have much time to write alot of text but i've posted alot of pics. If someone knows the "spoiler" command, please tell me so i can change it so we dont have this wall of pictures.

Specc on bike thats not stock (as far as i know)

-Lester rims
-Checkerd flag front forks
-john tickle rearsets.
-Yoshimura 550 high comp piston
-Yoshimura daytona Yr-2-31 cam
-Heavy duty springs (cant remember what brand)
-Rickman fairing
-MM front fender
-the 4-1 looks kinda homemade (?) sounds great though. pics further down
-Koni shocks

Color is called "mustard yellow"

First of: the bike when i got it was in good looking condition (althought the pictures i took of it wasnt)











I started to work on the Front end. Giving the fork lowers a good rubbing. Brake hoses were exchanged to steel braided type.










 Brakecaliper painted. Note the last picture is taken about 6 months after i polished the fork lowers, that magnesium is really oxidising fast. Gonna get some good quality clear coating on that this winter hopefully.








Stacks looking rough




Engine Tear down



Removing that primary carefully.





Getting rid of that broken of cylinder bolt as you might have seen in an earlier post.


Loose valve seat

Looking good now!



Yoshimura pistons soda blasted (grooves been cleaned out aswell)



Crank is well within spec


Newly painted, Used that RH Lack brilliant silver with etsing primer


Where we at now

The engine to the right is the one that was assemblied last year, its going into an orignal cb500 restoration (next years project) underneat is a spare one that acctually had some okay compression although cylinder walls are kinda rusted. maybe just rebore that at some point.




some inspiration



Cleaned up the electronics and powdercoated baseplate.


Found some brassrods and decided to do some stuff. not sure how well that will hold up.




Powdercoating some stuff



Wonder if powder coating will hold up on the silencer, you will only know if you try it.


The Horde

[minimo]

Looking like a fun build so far. Lovely looking Horde too.

[calj737]

Fork lowers should be cast aluminum, not magnesium. Unless they’re special aftermarket units? Aluminum oxidizes instantly as a means of self protection against the elements.

[754]

Yes he said Checkered Flag fork legs, they were like 99 bucks when they were new..
 They look a bit like Betor fork legs, like Rickman used, i like the 4 bolt bottoms.
 Looks like first generation Koni,s like I had.

Be careful on the brake rod,  brass is not very strong, it could let you down.

[Korven]

The fairing ive got is a rickman according to the previous owner. Seems wellmade. Frost fender is from a musclemachine.

[seanbarney41]

Very nice project and I love what you are doing with it.  Those forks are fantastic, there can't be many of those left in the world. 

I have used a set of very similar Tickle rearsets for a 400f only I adapted them to a cb750.  They are excellent, but beware if yours use the u-bolt around the frame tube mounting as they are capable of crushing your frame tube.  Also my footpeg rubbers wore very quickly.  I discovered that 1960's BSA footpeg rubbers fit well.

[Korven]

Very nice project and I love what you are doing with it.  Those forks are fantastic, there can't be many of those left in the world. 

I have used a set of very similar Tickle rearsets for a 400f only I adapted them to a cb750.  They are excellent, but beware if yours use the u-bolt around the frame tube mounting as they are capable of crushing your frame tube.  Also my footpeg rubbers wore very quickly.  I discovered that 1960's BSA footpeg rubbers fit well.

Yeah I think these are for the 400 as well. These use the u-bolt. You know what BSA footrubbers that fit? I don't even know a single BSA model. These seem to fit but look kinda bulky. Would be nice since the originals are cracked. I only glued them together with mediocre result.
I' was thinking of getting raasks since I live close to his shop/storage, but these turned out pretty decent. He's still got alot in stock it seems but a bit expensive at 300£

[seanbarney41]

I don't know the exact models that used them.  I knew the Tickle rearsets were made in England so I asked a local expert on british bikes and that is what he came up with.  Your ebay  ad looks close to what I used.  Yeah, kinda bulky, but holds your foot in place well.
550 etc 046 by Sean Barney, on Flickr

[Korven]

I don't know the exact models that used them.  I knew the Tickle rearsets were made in England so I asked a local expert on british bikes and that is what he came up with.  Your ebay  ad looks close to what I used.  Yeah, kinda bulky, but holds your foot in place well.
550 etc 046 by Sean Barney, on Flickr

They had a inside measurement of 16mm so I'll just have to measure mine once I get home. Noticed your 750 from some other post but the pic was rather blurry. Would you care to post some of your seat/backend, it caught my eye. I kinda wanna go with some more "modern" removable cut since sometimes GF wants to tag along.

[seanbarney41]

Hmmm, not sure what you are looking for pictures of.  I have had several cb750's posted on this site over the years.  I will post pictures of the two that I ride currently.  The gold bike has no provisions for passengers.  Orange bike is basically stock in the passenger department.DSCN1019 by Sean Barney, on Flickr
KIMG0059 by Sean Barney, on Flickr

[Korven]

Hmmm, not sure what you are looking for pictures of.  I have had several cb750's posted on this site over the years.  I will post pictures of the two that I ride currently.  The gold bike has no provisions for passengers.  Orange bike is basically stock in the passenger department.DSCN1019 by Sean Barney, on Flickr
KIMG0059 by Sean Barney, on Flickr

The first one I was referring to, sorry for the confusion. I like the bracket for the plate and brakelight. Image a seat just like that one with a removable cut (am I saying that right) throw on some nuts with wings for the footpegs and your ready to go if you got company. Not sure if there is some finished version of this.

This is what the back end looks like Atm.

[seanbarney41]

I think I know what you mean...a removeable cowl that goes over a stock sized seat, so that when in place you have a racy single seater, then just pop it off for an extra special passenger, like several more modern super sport bikes offer.  I think that is a great idea but quite difficult to make it look right on these old bikes. 

My suggestion would be to keep the stock seat with a bobbed rear fender...keeps the tailight and license plate looking period correct.  Maybe look at what old AMA Superbike Racers did with stock seats...simply took the seat cover off re-profiled the foam to be less bulky, and replaced the stock seat cover.

[seanbarney41]

My tailight is simply a stock early model tailight screwed to a stock grab bar with a hand bent and shaped aluminum license plate bracket incorporated.
DSCN1198 by Sean Barney, on Flickr

[Korven]

Bottom half is almost assemblied! Before appliying hondabond i was test mounting both crankcases just to see that i got everything just right. Righthad crankseal got a little beat up, dang it! not sure if its supposed to be fully pushed in or out, that aluminium edge is really sharp. Anyway, i need to source a replacement and im gonna get 2 extra hands for next time.

The new cam chain is a "heavy duty" RK chain.
Replaced the middle shiftfork and the "Exiting" double bearing

I Will work on getting the top end Ready while waiting for spare parts.

[Korven]

So i've got a replacement oil seal from a friend rebuilding his 750! (its the same number) Didnt have to wait 2 weeks for delivery. Bottom half is assemblied! Was pretty hard getting those Shift forks right while keeping everything else right, especially since you have that gasket paste! Was alot easier with help.

So found this instruction for the valve springs, but dont really understand the part about the progressively thingie (bottom left). I dont see any diffrence on both ends? As i understand it there should be more "laps" or "rows" on one end.

Edit: the text says "some" now I feel stupid. Hehe

[Korven]

Valves and springs are installed! Clearances all measured up!



Check out these 3 diffrent types of Spring retainers. The Bottom one is oem. the top one is with a grove so that the seal doesnt contact it i think.


 prepared the Cylinder by cleaning it ALOT after the honing. New piston rings ready to be installed.


in the last pic i found this plug in a box, i think its for the Starter perhaps? it had a little play in the hole but not sure what else it could be?

[calj737]

Starter block off plug

[Korven]

Starter block off plug

How am i supposed to use it? It doesnt stay put in the hole.

[754]

It should have an o ring groove, do you have lathe access ?
 Silicone or urethane might hold it.
 You can also drill and tap one side and use bolt and washer to hold it, but most are O ring.

[Korven]

It should have an o ring groove, do you have lathe access ?
 Silicone or urethane might hold it.
 You can also drill and tap one side and use bolt and washer to hold it, but most are O ring.

I was thinking of making A copy of that oil gallery plug, only bigger. This one is in some kind of hard rubber/plastic but there is nothin more to it.

Or perhaps one could do something like this. Had a few beers so this might not be the best idea. Check out those Paint skills!

[Korven]

All piston and piston ring clearances were within spec. Now just to get those pistons in that cylinder.



Ao before I get to installing the camå. Do I need to grade this can? If so, I don't have a adjustable sprocket. Can one of them be machined or should I get an finished product?  I was looking at the cams at webcam. Their streetcams have 280degree duration whilst this one seems to have 257/260, is this a really mild cam? The middle one is the yoshi cam.

[Korven]

Steady progress


So been researching about timing the cam. Since the sprocket has 35 or so teeth the cam could be as much as 10 degrees out of alignment without the adjustable sprocket. I'm gonna see what kind of play I get with the original sprocket just in case, if not for learning this process.

So if I understand I correctly. I align the cam with the marks in the head as one normally would do.  Then I would proceed to put the engine in true tdc

At .05" I would want the intake valve to be at 25 degree and also 50 at closing. Then see how much it is off, then either adjust a tooth or get a sprocket.

Now for the questions. Do I check this with .006 tapper clearance? It also says I should check piston to valve clearance (minimum seems to be around .060-0.080 according to the forum. Should I leave the tappets without clearance to check this (as when the motor is hot) or is this calculated in the minimum play?  Not sure if .006 tappet clearance adds the same amount piston to valve clearance?

Anyways would be greatly thankful for any response since the YouTube videos leaves me clueless.

PS. Saw that many cams use .006 for racing and .004 for street use. I won't be using this for racing.

D's. The cam card mentions 50 degree ignition. I wonder if this is the full advancement or if one locks the ignition at this position all the time. Not sure how I would run at idle with that setting.

[MRieck]

 Remove the rubber from the cam sprocket and slot it on a rotary table.

[Korven]

Big update!

I had some trouble fitting the chain to my sprocket but removed the rubber (was told this was a stupid thing to do, but cant really see any problem with it except it might be noisy.) the chain just wasnt seating properly with it. It was needed to come of anyways if the sprocket needed to be machined for the cam adjustment (it didnt)




So i managed to time my cam.

The values i got at .40 valve lash was

After 10 engine revolutions and taking the even of these 10 values (they were about 1 degree off, take that as measuring fault ex. 24,24,25,25,25,25,25 etc.)

In Opening spot on
In Closing 1 degree late
Out opening 1 degree early
Out closing 2 degrees late


One thing i noticed while timing the cam is that the inlet valve is begining to open at 49-50 btdc, Thats where the cam card says ill want ignition. My question is. if the valve is closing at 49 and the ignition occurs at 50 does this do any damage to the engine or just a powerloss?


Valve to piston clearance checked at 0 valve lash (as when engine is hot i suppose) aprox 2.5mm Inlet aprox 3.5 outlet







Wasnt sure if there were supposed to be copper washers on here. Cmsnl shows its normal ones but both this engine and my spare had copper washers here. There was an alu one where below the bracket but just went with double copper there since its discontinued. I didnt use Oem washers here since i cheaped out (they were like 3£ a piece on david silver) anyways easy place to change washers incase it leaks. The bike came with Allen heads on most visible screws so decided that it was an "upgrade" from the standard JIS. Not sure if this is something someone would do "back in the day" Anyways, they will do better on a original engine after some new zink.



Covers on just for "feeling" Not sure what i am gonna do with them. i bought an eastwood Clearcoat for my fork legs, maybe some of that on there after a good polish (and wax cleanup) (it was rated 150c)


Tires arrived, one of them was a 160/60 -17 Offroad supermoto tire so is awaiting a replacement. Had a really hard time tracing down valves for the lesters but i got a hold of some on ebay after spending hours googling. 11.5mm Tire valves are standard but the lesters are an uncommon 8.3mm. Once i get the back tire on and all assemblied i can get to work on the front end, again. Fork ears are getting removed since they dont have a function anymore. One brake hose needs to be rerouted or maybe get some other type of banjo connection that allows better routing. it hits the Head light slightly when doing full steering. Fork lowers are getting polished again and clear coated.

I ended up rebuilding the master cylinder. It was on the bike when i bought it but seemed to be leaking. Is the original master cylinder fine with dual discs or is it a big no-no? I think i have some weak memory that you can use the GL1000 master cylinder since it has dual brakes, not sure about this tho. is it really needed tho?

thanks for reading!

[flatlander]

One thing i noticed while timing the cam is that the inlet valve is begining to open at 49-50 btdc, Thats where the cam card says ill want ignition.

did you measure that with 0 lash or at running clearance?

Wasnt sure if there were supposed to be copper washers on here.

easy to remember: if there is oil underneath the bolts, use a sealing washer. meaning, one from a soft metal like copper or alu.

Covers on just for "feeling" Not sure what i am gonna do with them.

that breather cover is on backwards

I ended up rebuilding the master cylinder. It was on the bike when i bought it but seemed to be leaking. Is the original master cylinder fine with dual discs or is it a big no-no?

it's a matter of preference. there are people who use the stock size, and others who prefer a bit larger. mine is 16mm and i'm happy with it. at the same amount of lever travel, a larger one moves more liquid. so it's a compromise between those things the downside being that you can loose "feel" if the cylinder is too large.
all in all, with dual disc i'd say 14mm or larger would be best.