Topic: ‘71 CB 500 Four emerging from a deep sleep - valve cover question

[armyguns]

I have been in listening mode for the past couple of months as I continue to chip away at 25+ years of neglect on a 100% intact 71 CB 500Four.  I have learned a lot about this bike by using the search function and this Forum has been great!  I also have the Cycleserv manual and the Honda Parts List for reference material.

The bike was stored outside, under cover, but not well protected so there is a lot of surface rust that I will deal with.  There was about 2 gallons of what used to be gas in the tank. My first priority was to get the tank off and emptied.  The inside looked a bit rough but nothing that could not be cleaned.  The petcock was beyond hope, so a new one is now waiting for installation.  The carbs were completely fouled with the worst case of varnish I had ever seen.  They were shipped off to Mays Moto who did a fantastic job of bringing them back to life.  While they were out being worked on, I checked compression, set the valves, adjusted the points, set the timing, got a new battery and started cleaning things up.  The compression was 150 on three of the cylinders and 120 on the 4th.  I figured there was probably a stuck ring and I am hoping that will free up with usage.  When the carbs came back, I reinstalled them using an auxiliary tank.  The bike started right up and even idled nicely!  Since the engine seemed to be OK, it was time to get to work.  The clutch friction and pressure plates were pretty much fused together, so new plates were installed. The throttle cables were replaced. The clutch cover, point cover and left side crankcase cover, starter cover, and AC generator cover have been removed and polished back to shiny. 

I want to remove and polish the valve cover before I move on to the front and rear sections of the bike, but I want to be sure of the process before proceeding.  I was successful at getting every one of the pan head screws loosened on the cover. PB Blaster, heat and an impact driver did the trick. Some are slightly mangled and will be replaced.  My confusion is in what comes next.  The Cycleserv manual simply says “…unscrew 12 6mm screws and 6 bolts, and remove the cylinder head cover.”, however it is not clear which specific screws and bolts are to be removed.  What about the 4 nuts that are obviously screwed down onto 4 studs under the breather cover? Also, I have seen other references that state to fully loosen the valve tappet screws prior to cover removal and then use rubber bands to pull the tappets up during reinstallation.  I don’t want to screw something up so I am looking for clear information on the correct procedures. 

Does anyone sell a complete bolt/screw replacement kit for the valve cover? 

Any help will be greatly appreciated! 

[exponent]

The 4 screws under the breather covers are holding the pins for the rocker shafts, no need to undo them to remove the valve cover. Using rubber bands is really important because if not used there's a possibility of bending or breaking the hardened rockers.
Bolt depot has every bolt you could need in the proper strength.

[Stev-o]

First off, sounds like you are doing all the right things to bring this bike back.

+1 to the "rubber band trick".

Use rubber bands over the top of the valve cover, the end loops of the rubber bands go down through the tappet-cover holes and then wrap around the valve lifters. This holds them up and away from the valve stems to keep them from binding as the cover is being screwed down.

It is also important to fully back-out the valve adjuster (the nut-screw combo) so that there is the maximum possible clearance between the lifter and the stem.

I get stainless socket head screws at a fastener specialty store but some guys say their local Ace Hardware has them too.

Or, you can buy this kit...

https://www.ebay.com/itm/132240646570?hash=item1eca2821aa:g:GkoAAOSw7bZdtJDv&amdata=enc%3AAQAHAAAA8A6%2B2zJJnapZlCMaq0hSc%2FKdev0TWw1u1oacWw6f3xVV8ouPQ8gt4OMgqfOgeH%2BTH5xxU0%2FLBfBSTKot%2BINZVMeY9LLJOHc9uoTs%2F5fai5aVdyOCnh4ezYNv6AFePzbc4GU8amPI4%2FkpwiViBPwMJh%2BwXuTs9cZON5MNMbp72zg8F9OdbX%2BNZzH5Ny4IiSzkRLvcV1ewVYOVZyGKtaITEaxX3cmTxi96vJFw9%2F4B%2BK3qU3d%2BYwSfyBnjMKPDaC4sBaJZotHok6CN5w8bVhYWfxyNZ9srdP%2BrM1uJrD6CcqdUwvgqvXAXaN67NEOg3CVUkA%3D%3D%7Ctkp%3ABk9SR_KL6dvlYQ

Consider starting a thread in the Project Shop area so we can follow along. Good luck.

[newday777]

Welcome aboard armyguns

[craz1]

With it being a CB500 and sitting for 25 years i'm surprised it has the later style cam cover from the later CB550(like 1978). But he is describing 4 bolts on studs so it must have been updated. Lucky you!

[calj737]

Be wary of using socket head screws on the valve cover. Some will not permit adequate clearance. What is better is to get stainless JIS screws or stainless button head cap screws. Even sexier are stainless Torx screws if that’s your cup of whiskey…

The 500/550 platform has different clearances on the valve cover than a 750 so that is where the habit of purely using socket heads comes from.

[wolf550]

I remember on some of the screws near the tappet head covers I couldnt use hex or allen bolts due to not being able to get the tappet covers on. either tightening the bolt and trying to put on tappet cover or putting on tappet cover and tightening the bolt so I just used the phillips jis screws.

[armyguns]

With it being a CB500 and sitting for 25 years i'm surprised it has the later style cam cover from the later CB550(like 1978). But he is describing 4 bolts on studs so it must have been updated. Lucky you!

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I have no idea of the differences between the cover styles but I can verify that under the breather cover there are 4 bolts with 10mm heads.  There are also 4 10mm nuts with a washer screwed down onto either a bolt inserted from underneath or a stud screwed down into the cam cover.  Since I have not yet take it apart and I don’t find a reference to those 4 nuts in the Parts List or the Cycleserv manual, I have no idea what I have!  The VIN plate has 3/71 as date of manufacture, and the engine number is CB500E-1001984. Any information that is available will be helpful.  Just point me in the right direction! 

I don’t have any service history on this bike but it was not apparent anyone had removed the cover before me. Same with the clutch cover and other engine covers.  However, the tappet covers had definitely been removed multiple times as some of them were pretty chewed up. Someone had removed the carbs too, based on the badly deformed carb to intake isolator that I found on cylinder 3.  They had somehow folded/rolled the insulator at about the 4 o’clock position, tightened up the clamp and ran the bike that way.  It must have had a terrible vacuum leak, if it ran at all.  I just don’t know. 

[bryanj]

Can you put up a pic of what you see under the breather cover?
If you go to the uk site and look in either alladins cave or ashs dropbox you will find all the bulletins for the 500/550 and one of those explains the valve cover mod.
It may be you have the early "square" front crankcases and possibly the early neutral detent mechanism

[armyguns]

Here are a couple of pictures of the top and bottom of the valve cover and a picture of the top of the engine showing the cam and valve springs.  In the cam picture I am pointing to a missing seal.  Near as I can tell, this seal just covers over access to the head bolt nut and really doesn't "seal" anything.  It just wasn't there when I removed the valve cover.  Is this something I should be wary of and should it be replaced while I am in there?  Can anyone enlighten me on what style of valve cover this bike has?  By the way, the bottoms of the rocker arms and the cam lobes look fine.  No obvious signs of wear. 

[Stev-o]

In the cam picture I am pointing to a missing seal.

The missing seal is what we commonly refer to as a "puck", Honda calls it a sealing rubber.  You def want to replace all these as it will prevent your motor from leaking, a very common issue.

Here is a link to the part, #18, and the parts fiche, bookmark it for future reference...

https://www.southsoundhonda.com/--xpartsstream#/Honda_Powersports/CB500K1A_MOTORCYCLE%2c_JPN%2c_VIN%23_CB500-2000001/CYLINDER_HEAD_%2b_CAMSHAFT/893400f5-1ca1-4586-9ff3-e8a62d9107fb/9d652b7b-2713-4800-bbfb-255b8af9415a/y

[craz1]

It appears you have the later cover. The difference is the cb500 and early CB550 had 8 rocker shafts, one for each rocker. These were not pinned and would rotate causing wear on the cover itself, where the pins slide into. After many miles it would be hard if not impossible to set clearances because the shaft and rocker would have that extra up and down play. The newer cover has 4 long shafts each holding 2 rockers and are pinned (the four nuts/pins you see under the breather). The pins prevent the shaft from rotating so no wear on the cover. These cover are getting hard to find. I just sold one that I was hanging onto.

Also that missing seal looks to be sitting on the cylinder head. Take a look at you last picture, it's on right of the photo. May have fallen off and landed there when you removed the cover. Make sure you replace those and use a sealant.

[newday777]

Your missing puck......

[RAFster122s]

HondaMan, Mark Paris has noted that the Honda OEM pucks haven’t been the proper thickness for several years now leading to leaking not long after reassembly. There are a couple aftermarket shops that have proper thickness pucks. The South Sound Honda shop is one of the cheapest sources for OEM original Honda parts, so keep them in mind for bigger orders of Honda parts. Their shipping fees are typically that of what they incur, better than many shops fees. Their discount often covers the shipping fees when buying many things. Local dealers you should try to keep in business too, so throw some business their way and after a while they may offer some small discounts on some things.

David

[armyguns]

It appears you have the later cover. The difference is the cb500 and early CB550 had 8 rocker shafts, one for each rocker.
<snip>

Also that missing seal looks to be sitting on the cylinder head. Take a look at you last picture, it's on right of the photo. May have fallen off and landed there when you removed the cover. Make sure you replace those and use a sealant.

Thank you for the clear explanation of the cover difference!  Thank you, again, for spotting the wayward seal!  I was so focused on the fact it wasn’t where it should have been that I totally missed seeing where it was.  Hidden in plain sight. 

[armyguns]

HondaMan, Mark Paris has noted that the Honda OEM pucks haven’t been the proper thickness for several years now leading to leaking not long after reassembly. There are a couple aftermarket shops that have proper thickness pucks. The South Sound Honda shop is one of the cheapest sources for OEM original Honda parts, so keep them in mind for bigger orders of Honda parts. Their shipping fees are typically that of what they incur, better than many shops fees. Their discount often covers the shipping fees when buying many things. Local dealers you should try to keep in business too, so throw some business their way and after a while they may offer some small discounts on some things.

David

David-  I have been locally sourcing a bunch of the parts. The Honda parts guy has been really great in helping me find parts that he doesn’t have in stock, but other local dealers do. 

You mentioned some aftermarket shops that source the proper thickness seals.  Can you recommend someone to check with?  I see that the seals are pretty commonly available by searching the OEM part number, but if better fitting seals are available I would rather get them.  Thanks for your help!

[RAFster122s]

HondaMan, Mark Paris has noted that the Honda OEM pucks haven’t been the proper thickness for several years now leading to leaking not long after reassembly. There are a couple aftermarket shops that have proper thickness pucks. The South Sound Honda shop is one of the cheapest sources for OEM original Honda parts, so keep them in mind for bigger orders of Honda parts. Their shipping fees are typically that of what they incur, better than many shops fees. Their discount often covers the shipping fees when buying many things. Local dealers you should try to keep in business too, so throw some business their way and after a while they may offer some small discounts on some things.

David

David-  I have been locally sourcing a bunch of the parts. The Honda parts guy has been really great in helping me find parts that he doesn’t have in stock, but other local dealers do. 

You mentioned some aftermarket shops that source the proper thickness seals.  Can you recommend someone to check with?  I see that the seals are pretty commonly available by searching the OEM part number, but if better fitting seals are available I would rather get them.  Thanks for your help!

Had to use a little Google Fu to dig up HondaMan source mentioned…

PartsNMore

https://www.partsnmore.com/parts/?q=91318-300-013


To use Google search for the site use format of your search term(s) followed by “site:forums.sohc4.net”

[newday777]

HondaMan, Mark Paris has noted that the Honda OEM pucks haven’t been the proper thickness for several years now leading to leaking not long after reassembly. There are a couple aftermarket shops that have proper thickness pucks. The South Sound Honda shop is one of the cheapest sources for OEM original Honda parts, so keep them in mind for bigger orders of Honda parts. Their shipping fees are typically that of what they incur, better than many shops fees. Their discount often covers the shipping fees when buying many things. Local dealers you should try to keep in business too, so throw some business their way and after a while they may offer some small discounts on some things.

David

David-  I have been locally sourcing a bunch of the parts. The Honda parts guy has been really great in helping me find parts that he doesn’t have in stock, but other local dealers do. 

You mentioned some aftermarket shops that source the proper thickness seals.  Can you recommend someone to check with?  I see that the seals are pretty commonly available by searching the OEM part number, but if better fitting seals are available I would rather get them.  Thanks for your help!

Had to use a little Google Fu to dig up HondaMan source mentioned…

PartsNMore

https://www.partsnmore.com/parts/?q=91318-300-013


To use Google search for the site use format of your search term(s) followed by “site:forums.sohc4.net”

Any idea how much thicker they are than the Honda seals? Any reference to actual measurements?

[RAFster122s]

PM Mark or drop him an email, he is super analytical and would have that data. I'm sick with a respiratory virus since last Sunday and trying to limit bright screen time as the headache is a bit photophobic...

[RAFster122s]

They need to be .040" thicker than the puck recess depth for a good seal (and you should still use sealant on them)
That’s all I have found…

I sent Mark an email asking him to pop by with some info…

David

[armyguns]

They need to be .040" thicker than the puck recess depth for a good seal (and you should still use sealant on them)
That’s all I have found…

I sent Mark an email asking him to pop by with some info…

David

I look forward to info on the better pucks!  Any recommendations on what sealant to use for the pucks and also for the valve cover packing?  I see that the original packing had some sort of brownish gasket sealer on it.  I assume that was applied to help keep it in place during installation of the cover.  I have a tube of Hondabond 4. 

[newday777]

Yes hondabond is the stuff to use.

[HondaMan]

You guys have it right: the proper seals for these engines are about 0.040" (0.1mm) thicker than their holes' depths at the grooves around the perimeter. The sources I've most used recently are PartsNmore.com and CB750Supply.com . They sell 2 different brands: PartsNmore is selling the black ones individually and CB750Supply is selling the blue ones that come in a pack of 6. Both work fine.

A looong time ago I dug into the sealant Honda used in the K2 engine (mine) and the closest stuff I could find in the US that was like it was/is Permatex#2. I've seen the Hondabond/Yamabond used as well, and both seem to work. The seals are much harder to remove once the Hondabond-ed ones cure, though.

I've also seen the mistake of someone using the Permatex#1 instead (hardening type), and it wasn't good. It was used on the too-thin ones that we were getting around 2000-2006 or so, and the goo turned to concrete with the top end heat, make it real hard to clean away - and they leaked like they weren't even there!

[newday777]

You guys have it right: the proper seals for these engines are about 0.040" (0.1mm) thicker than their holes' depths at the grooves around the perimeter. The sources I've most used recently are PartsNmore.com and CB750Supply.com . They sell 2 different brands: PartsNmore is selling the black ones individually and CB750Supply is selling the blue ones that come in a pack of 6. Both work fine.

A looong time ago I dug into the sealant Honda used in the K2 engine (mine) and the closest stuff I could find in the US that was like it was/is Permatex#2. I've seen the Hondabond/Yamabond used as well, and both seem to work. The seals are much harder to remove once the Hondabond-ed ones cure, though.

I've also seen the mistake of someone using the Permatex#1 instead (hardening type), and it wasn't good. It was used on the too-thin ones that we were getting around 2000-2006 or so, and the goo turned to concrete with the top end heat, make it real hard to clean away - and they leaked like they weren't even there!

Mark
What is the thickness needed of the seals?
And are the current Honda seals too thin now?

[HondaMan]

You guys have it right: the proper seals for these engines are about 0.040" (0.1mm) thicker than their holes' depths at the grooves around the perimeter. The sources I've most used recently are PartsNmore.com and CB750Supply.com . They sell 2 different brands: PartsNmore is selling the black ones individually and CB750Supply is selling the blue ones that come in a pack of 6. Both work fine.

A looong time ago I dug into the sealant Honda used in the K2 engine (mine) and the closest stuff I could find in the US that was like it was/is Permatex#2. I've seen the Hondabond/Yamabond used as well, and both seem to work. The seals are much harder to remove once the Hondabond-ed ones cure, though.

I've also seen the mistake of someone using the Permatex#1 instead (hardening type), and it wasn't good. It was used on the too-thin ones that we were getting around 2000-2006 or so, and the goo turned to concrete with the top end heat, make it real hard to clean away - and they leaked like they weren't even there!

Mark
What is the thickness needed of the seals?
And are the current Honda seals too thin now?

The correct ones are 2.90 to 3.00mm thick at the outer rim.
The incorrect ones are 2.6 to 2.7mm thick at that rim.
I've seen even thinner ones, but they were not for bikes (that I know about?).