Topic: 550 rocker cover fix

[BomberMann650]

I don’t think drilling more holes into that part will net any horsepower gains 

The only reason the valve covers get damaged was because the shaft would rotate and push its way into the metal.  If the shaft didn’t rotate, we wouldn’t see this problem.

[strynboen]

yes 40 years of bad engine oil..is the real killer..thats vhy some engines dies and other lives onn..no matter of miles...dirty oil grinds the soft alu..the hardent pin holds fine..so the soft parts must go...

back then noone thorth this bikes vil live for 40 years+...so thange oil vas not somthing all did..at regulær basis...
not like today..vith long intervalls..oil vas short lived back then..like thepy oil today..

[titan joe]

Just my thoughts here... And this really plays no bearing on the subject of thread -  repairing a bad valve cover....

I drilled oil holes for the pins a cover that is in very good shape. Here's my thinking...

The pistons are a fully floating type which means that the gudgeon pin floats on the oil in the connecting rod and in the aluminum piston. Most pistons have a hole of two in the cylinder to allow splash lubrication to oil the pin. We don't see these wearing out and they transmit full engine power to the rest of the system. Floating pins have less friction than stationary ones, or so I have been told when reading about SBC 350s. I thought I read a reference to floating rocker arms on the 750 in the thoughts of Hondaman thread and that locked-style ones rob power. BUT, maybe the pistons are made out of a better alloy than the valve cover.

That takes us to the next aluminum/steel oil film interface, the camshaft journals. These are force-lubricated from the bottom and with a significant gap between the top and bottom journal halves. Not my favorite design, but they seem to work. Most of the force exerted on the cam journal is in the direction of the head where it is receiving fresh oil, so this is probably not the most fair comparison either.

Given the position of the one that wear I would guess that the oil is cooked and looses viscosity and allows metal to metal contact and wear in the bore. Really the oil should keep all rotating parts from touching stationary parts in the engine and if there is that oil, a hardened steel shaft should never wear out a lead bore. These old bikes are known to cook oil pretty quickly, like strynboen is getting at.

Anyway, those are my thoughts. I would love to see a bushing insert repair to maintain the fully floating rocker design, but I think that it will require an oiling hole regardless.

Here's what I did and we'll see what happens. This may be baloney.

[dave500]

small end wrist pins have more of a round and round even pressure cycle than the rockers up and down up and down back and forth partial rotation with constant steady heavy valve spring pressure in the same direction on them.

[BomberMann650]

If you’re keeping all eight rocker shafts in a good cover.  Use those holes to sink a screw into the shaft. The problem is not oil starvation.

The odd thing about the wear patterns on the 550 rockerbox is the lack of consistency.  You can have 3 worn bores, you can have 1, maybe 5 if someone wasn’t paying attention to the noise.  It seemingly happens at random.  Like a lighting strike.

The manifacturers proven way to keep a good head from eggin out, is to keep the damn things pinned in place.  No oil pathway needed.

[Hasenkopf]

here you go......

[TwoTired]

here you go......

Nice.

That's what I'd planned to do in my spare time, (like I have some).

When is the install and test run happening?

Cheers,

[ts354]

Hasenkopf - are you going to do anything to the rocker arm shafts?  Like grind a flat on them where the set screw will be?

[Hasenkopf]

yeah, they won't be going anywhere.

[Bootsey]

Thats looks like a solid fix Hasenkopf.

I've often pondered if the valve cover end caps could somehow be modified to keep the shafts located - an adaptation of the plug portion that has the o-rings, made to have something press into threaded hole in end of the shafts as it is fitted.
Whether or not this is feasible, or could be done so to be aesthetically pleasing may be the question.

[RAFster122s]

As the rocker shaft wear upward it is wearing the outside of the bore first, but as it tips to an angle it is also wearing the other end of the shaft because the wear on the cam and the rocker arms shifts because of that rolling motion or tilt.
But if it wears at an angle then it is digging into the bore at the opposite end  in the opposite direction, right?
Since we have 8 short shafts would it be better to replace those with one long hardened tool ejector pin cut to length needed?  Then seal the end with, cringe, a blob of RTV or Hondabond?
Will you need to secure it in multiple places? If  locking the shaft in one place like the later cover is enough to prevent spinning, you should not have movement unless the bores were worn, then each shaft would need it at both ends so it would even out the pressure. If you eliminate spinning you eliminate ability of it to wear into that bore.  Are dry film coatings of a rocker shaft possible to increase oil clinging to the surface and therefore not causing the rocker arms to wear...their oil  ports should not allow them to wear significatly unless any hardened coating were worn away.  New rocker arms only have their stellite or hardened faces on the rocker arm lobe, right?

[TwoTired]

As the rocker shaft wear upward it is wearing the outside of the bore first, but as it tips to an angle it is also wearing the other end of the shaft because the wear on the cam and the rocker arms shifts because of that rolling motion or tilt.
But if it wears at an angle then it is digging into the bore at the opposite end  in the opposite direction, right?

I didn't see that in the covers I have.  When it wears, it wears upwards.  Forcing the shafts back down with the set screws, corrects the rocker arm geometry.  The rockers readily pivot on the steel shafts.  The shafts don't need to spin.  I would expect just about any device that hinders shaft rotation would prevent further cover wear.

Since we have 8 short shafts would it be better to replace those with one long hardened tool ejector pin cut to length needed? 

Wouldn't hurt, and you could then use just one set screw per shaft.  There is still some supporting material, just not at the end of each of the 8 shaft ends.

Then seal the end with, cringe, a blob of RTV or Hondabond?

If you are not boring the cover shaft ends, the orings in the end caps should still function as before.  That surface doesn't wear.  No need for extra sealant.

Will you need to secure it in multiple places?

The eight shafts, yes.  16 set screws.  Or, one for every worn shaft bore bearing surface.   If reducing to four shafts, probably only need one set screw per shaft, just to keep it from turning. 

If  locking the shaft in one place like the later cover is enough to prevent spinning, you should not have movement unless the bores were worn, then each shaft would need it at both ends so it would even out the pressure. If you eliminate spinning you eliminate ability of it to wear into that bore.

Yes and yes.  Agreed.

Are dry film coatings of a rocker shaft possible to increase oil clinging to the surface and therefore not causing the rocker arms to wear...their oil  ports should not allow them to wear significatly unless any hardened coating were worn away.  New rocker arms only have their stellite or hardened faces on the rocker arm lobe, right?

I've not seen ANY shaft to rocker wear.  I don't know if the rocker shaft bores are hardened.  I wouldn't expect that , though.

I did try to fit the Honda 4 shaft solution into the old rocker cover.  It was too long to fit without modification to cover (bore deeper), or shaft (cut shorter).

Do you have covers that need fixing?

Cheers,

[RAFster122s]

Yes I do, one lightly worn and the one currently on the bike is significantly worn...
Would prefer to have a late cover...but sometimes it does not work out that way...

David