Topic: Honda CB750 valve cover dilemma

[kyle750]

My valve cover looks terrible and the flaking looks very similar to my oil filter housing unit.  The oil filter housing was chrome plated (not painted) and the remaining plating could not be sanded off.  Super strong bond.  I cleaned up the oil filter housing as best as I could and repainted in a high temp silver.  Looks OK but not great.

I suspect the valve cover has also been chrome plated and not worth the trouble to refinish

I'm looking at replacement valve covers and plenty are available and for sale.  As this is not a high demand part prices are cheap. I can buy an original with factory original finish or a vapor honed cover for about double the price.  There are also polished covers that looks nice and shiney but too much bling and future maintenance for my liking.

Late Edit:  I tried test sanding the valve cover and the plating will not sand off.  Definitely chrome plated like the oil filter housing.   IMO just not worth the time and expense of having the cover blasted.   

[Ozzybud]

Originally they were satin polished and clear coated. Its a great look.and requires no maintenance.

Until it yellows 40 years later.

[kyle750]

^ ^ ^  Looks Perfect ^ ^ ^ I would be thrilled with that look!

[HondaMan]

The acid-dipping process that was often used for the plating of these covers was really harsh on the zinc-aluminum pot metal they are made from. It made the copper (if even used) undercoat for the chrome plate to be erratically attached (and not) in spots. I have not seen a chrome-plated cam cover survive to even the 1990s. I have used them as tools, though: I have [at least] one with the tops cut open so I can watch oil distribution in real-time when running an engine, or when oiling-up a freshly rebuilt one: you can watch the oil arrive and how it distributes across the rockers (it gets messy above 4k RPM, though...).

[spotty]

i've got a really scruffy one that will go on the chopper in the future, for now its going to get the fins removed and probably the valve inspection holes filled and sanded smooth, won't need them as there's plenty of room in a chopper frame to get the rocker cover off in the frame and lets be honest, who's ever done that before, might also weld and smooth out the breather in the centre too, or get proper hard fins ( as opposed to the soft woosy ones on the rest of the valve cover ) milled into it then weld it on

[Don R]

 Here's a chromed one that survived. I do have others that did not survive the journey to 2025.

[kyle750]

^ ^ ^ WoW ^ ^ ^

[kyle750]

I will try to post some CB750 valve covers that are currently for sale and available

1.  Sand Blasted

Not for me! Too much of a dull grey color and too much texture

[willbird]

I have had some stuff sand blasted and then vapor blasted, IMHO it looks nicer than just vapor blasting. I have a local guy who can vapor blast stuff for me, does nice work.

[kyle750]

I have had some stuff sand blasted and then vapor blasted, IMHO it looks nicer than just vapor blasting. I have a local guy who can vapor blast stuff for me, does nice work.

I'm not exactly sure if I understand what vapor blasting is?  High pressure water with different mediums added??

[Stev-o]

I have had some stuff sand blasted and then vapor blasted, IMHO it looks nicer than just vapor blasting. I have a local guy who can vapor blast stuff for me, does nice work.

I'm not exactly sure if I understand what vapor blasting is?  High pressure water with different mediums added??

Yes, also called water blasting or vapor honing, same basic process.  IMO, the best process to restore bare aluminum.  I had the entire engine [case, cylinders, heads and carbs] vapor blasted when rebuilding my Kawasaki 750, still looks great 3+ years later [the Kaw's motor did not come painted from the factory]

[kyle750]

Thanks for the explanation Mate.  Vapor blasting on the Kaw engine really turned out well. 

2. Vapor honed

Here is a listing for a Honda CB750 valve cover that has been vapor honed according to the seller.  I really like this look.  Old clear coat is removed,  aluminum is cleaned of debris and grease, and any ageing spots or black stains are removed.  IMO this cover looks great and the aluminium has a natural looking finish. 

[MauiK3]

Either satin sanded and clear coated or vapor honed would be my choice. I did some buffing before clear coating

[HondaMan]

The vapor-blasting outcome is terrific: it helps to seal the porous casting surfaces. Sadly, the one place here that did a great job of it closed up during the Covid nonsense, never reopened.

[kyle750]

Here is another vapor honed CB750 valve cover currently for sale

[kyle750]

Either satin sanded and clear coated or vapor honed would be my choice. I did some buffing before clear coating

Beautiful work!  Everything turned out looking fantastic.  Wonderful to see all the parts in a group and excellent project planning to finish them all at the same time so they are uniform and matching.    Very, Very Smart!

[kyle750]

Here is another valve cover currently for sale as a comparison

3.  Painted

Not for me!  Although this painted cover looks great (to my eye the color and texture looks similar to sand blasted) I have no idea how well the aluminum was cleaned and prepped. Eventually and over time it is very likely the paint will flake or peel.   IMO painted looks perfect on engine cases with slightly rough, textured surfaces but not on smooth covers.

[spotty]

Well it seems I won't be welding up the valve inspection holes, got these off Terry out of his stash of rare and dusty parts. Don't know if they're one offs but they were definitely hand machined not cast, the lathe marks are still visible in the centre

[bryanj]

Somewhere i have a set of those bought many years ago from fleabay

[kyle750]

4.  Chrome plated

This vintage CB750 valve cover has certainly aged gracefully and is in much better condition than my chrome plated cover. Very shiney and bright but chrome is brittle, chips, cracks, and is very difficult to refinish.  Aluminum is a wonderful metal  - why cover it up with chrome? 

[MauiK3]

I've never been a fan of chrome plating aluminum engine parts, I've seen many flake off. Some of the "vapor honed" parts look a bit rough to me, very dull. Makes me think the process is done differently by different people. Some look excellent, some not so much.

[kyle750]

Some of the "vapor honed" parts look a bit rough to me, very dull. Makes me think the process is done differently by different people. Some look excellent, some not so much.

Totally agree.  Vapor honed covers I have seen for sale are very inconsistent.  Maybe just different lighting in the photos but some look like a dull grey rather than a bright silver. 

5.  Polished Aluminum

Honda CB750 valve cover from a well known seller who sells polished parts.  I've never polished aluminum so I can't comment on the quality of this type of work. Expensive cover but looks like lots of time went into this. IMO a great looking cover - smooth finish and bright silver color.

[spotty]

Somewhere i have a set of those bought many years ago from fleabay

Excellent, now you need a chopper to put them on

[kyle750]

Last Option (perhaps there are more options that I am not aware of?)

6.  Vintage Original Factory Finish

Lots for sale in various condition with some in very good shape.  Not refinished, not blasted, not vapor honed, not polished, not painted, not chrome plated.  You have to look through many for sale in well worn and rough condition but there are some good ones for sale.  Cheap too!

In this photo you can see that the original clear coat has yellowed but the aluminum appears to be in decent shape without a lot of wear or staining.  I believe this cover would refinish nicely.

[willbird]

I've never been a fan of chrome plating aluminum engine parts, I've seen many flake off. Some of the "vapor honed" parts look a bit rough to me, very dull. Makes me think the process is done differently by different people. Some look excellent, some not so much.

IMHO you are exactly right, there are far more than one maker of vapor honing setups and then some folks create their own setup. Whether or not the part is dry blasted first seems to make a difference, I prefer the look of dry blast and then vapor bast.