Topic: 75 550 fix typical rocker shaft wear?

[hellraiserDLX]

I know this can be fixed with the updated valve cover/rockerbox assembly , but I can't seem to come across one. I think I saw a write up on how to fix the old ones with set screws, but I can't find it anymore with the search.  If anyone could help out with this topic my bike and my ears would be very appreciative!

[TwoTired]

I suggested this a a possible fix.  But, I haven't had the time to implement it.
I know Scottly asked for a cover to experiment with.  But, I haven't heard whether he got one to try out.

I do have a spare worn cover to try it on.  And it seems straight forward enough to implement.  I just need the time to try it.
 The valve spring pressure wears the shaft holes oblong and upward, leaving the bottom half of the shaft bore intact.  There are eight shafts in the cover which need each end of each shaft forced down to the bottom of the shaft bores.   The idea involves drilling in from the top of the cover into the shaft bore, then tapping the hole for a set screw which would then be installed after the rockers and the shafts were in place in the cover.  I guess 16 holes and screws would be needed for completeness.  But, it might also be done to only those positions where the wear is excessive.  Personally, I'd want to at least stop each shaft from turning even if they currently had good bore positions, and one set screw per shaft would do that.  However, to insure that the shaft geometry was maintained, worn shaft holes would need two set screws per shaft. 
I have both a drill press and a Drill/mill/ lathe which seem handy for the project.  I suppose with sufficient care, even a hand drill could be used, though.  Prowess dependent.  I'd select Loctite 2422  to seal the setscrews and keep them from loosening, as well as withstand the heated environment.

I'm supposed to be prepping the house exterior for paint and then painting for upcoming sale.  But, that isn't very exciting or interesting.

[hellraiserDLX]

I knew I saw something like this before. Thank you for that. I guess ill just have to pull it apart to see where the screws would be able to be put in place. I have a few buddys with nice machines to use, but the actual placement of the set screws is my only delema. It would be a lot easier if I jad the cover sitting in front of me I suppose haha.

Don't feel so bad about painting the house.  I clean cars for a living hahaha

[754]

You will have to set the bores up so they are in a perfect straight line, then clock in the unworn part, the bore out or use and endmill in a fairly rigid spindle,
 If you offset the bore you can get away with a possible slight ratio change or adjustment screw problem.  How far apart are the bores ? And is there a straight shot at them
?

[Duanob]

TT you might have a side bidness for fixing the older style covers. 

On the subject of the OP can't find one there are usually quite  few of them on ebay. You need to know how to ID them. Older style on top two pics, newer style bottom two. There are four keeper studs inside the camchain cover.

[Trad]

I just put an o ring between the cover end caps and the shaft ends. It sandwiches the shafts and prevents them from spinning. I have zero rocker wear on my old style cover. Just a thought. If yours are already worn this will only prevent future wear not fix what you already have going on.

[hellraiserDLX]

I have been trolling the bay for awhile in search of the new style but with no success. Thanks for the pics though. The rattle ia bad enough by cylinder one that I don't think I even need to look at the wear physically to know that the o ring wrong work on that one.  I think ill just keep looking for an updated version and tinker with the old one when I swap em. Thanks guys!

[Hasenkopf]

you could always bore the shaft and pressueize the hollow shaft with oil and an external line.....

[wally550k0]

I found the kit at http://www.hondarestoration.com but I think I got his last one.  Try CMS.

[scottly]

I suggested this a a possible fix.  But, I haven't had the time to implement it.
I know Scottly asked for a cover to experiment with.  But, I haven't heard whether he got one to try out.

No, I never did, but after seeing Duanob's pics, I have a much better idea of what would be involved. The hole locations would have to be mapped from the bottom side of the cover, using the dowel holes as the reference points, then flipped over for the machine work. A flat spot would need to be milled for each hole before drilling, as a drill will drift when feeding into an angled surface. This is a mill job. 

[TwoTired]

I had some time to take some pics.

The first shows a wooden dowel which is now inserted in the shaft bores.
I've taped the end cap and it's dowels onto the end to register where the end of the shafts will be after assembly.
I also taped the shafts onto the top of the cover to register where the set screws should contact where the rocker bearing surface is not.

The second pic shows the coarse location where the set screw holes would be drilled and tapped marked in red grease pencil.

The set screws should push the shaft down onto the bore "floor" which doesn't have the worn surface to upset rocker geometry.

[TwoTired]

A mill would be great for this job.  But, you could chuck the end mill in a drill press to flat the surface, and then drill into the flat.

I can't imagine the set screw locations are super critical.  But, the setscrew must hit the highest point on the shaft somewhere along the screw end width.

I thought about the set screw gouge later in life when dissassembly is required.  Maybe there should be a flat ground on the shaft set screw points, so the gouge cant score the rocker inner bearing surface during extraction.

[scottly]

I also considered the gouge left by the set-screws; this shouldn't be an issue with bores so worn that they need this fix? Most drill presses have a lot of slop in the spindle, and don't make very good mills. My concern is how much "meat" there is to support the load on the screw threads in the cover where the holes go.

[Duanob]

Not many available currently. I guess timing is everything. There were lots earlier this past summer. I found one but it seems pricey for the condition. However it does have free shipping. If it doesn't sell maybe you can make the seller an offer.

http://www.ebay.com/itm/1976-HONDA-CB550-CB-550-VALVE-COVER-HEAD-ENGINE-MOTOR-/390343513170?pt=Motorcycles_Parts_Accessories&hash=item5ae2495452&vxp=mtr

[TwoTired]

I also considered the gouge left by the set-screws; this shouldn't be an issue with bores so worn that they need this fix?

Not worried about the shafts scoring the cover bores.  Rather sliding the rockers off the shafts and scoring the bushing in the rocker.

[hellraiserDLX]

 This sounds like I should send mine to twotired when he seals the deal

[TwoTired]

you could always bore the shaft and pressueize the hollow shaft with oil and an external line.....

I don't believe it is an oiling issue.  The bores on the failed units I have seen were always well oiled, flooded in fact.  The rockers are supposed to rotate on the shafts.  Shafts are steel and the rockers are bushed, I think.  Sometimes the rockers are tight enough on the shaft that the shafts turn in the soft aluminum along with the rocker movement.  Even if oiled the aluminum is sacrificial when rubbed on by steel.

I'm not convinced that the orings against the end shafts are an effective cure.  I don't think they hurt.  But, there hasn't been evidence that it is a long term cure.
The worst part about the wear is that it is not even or equal at each end of each shaft.  This tilts the follower face at the cam lobe interface, leading to galled cam lobe and follower faces.  O rings certainly won't cure this uneven wear geometry issue.

[scottly]

I also considered the gouge left by the set-screws; this shouldn't be an issue with bores so worn that they need this fix?

Not worried about the shafts scoring the cover bores.  Rather sliding the rockers off the shafts and scoring the bushing in the rocker.

Good point. Are the rockers bushed?

[bwaller]

No.

[scottly]

Thanks Brent. I didn't think they were, but wanted confirmation from a 550 expert.

[TwoTired]

I also considered the gouge left by the set-screws; this shouldn't be an issue with bores so worn that they need this fix?

Not worried about the shafts scoring the cover bores.  Rather sliding the rockers off the shafts and scoring the bushing in the rocker.

Good point. Are the rockers bushed?

I couldn't remember if they were bushed for this engine or not.  I checked my spares and it doesn't appear so.  But, it is irrelevant to the issue.  I still don't want the rocker bearing surface to be scored by a bur on the rocker shaft as it slides off the shaft.

[TwoTired]

This sounds like I should send mine to twotired when he seals the deal

I expect Scottly is way more interested in getting your business than I am. 

If I do it, it will likely be a trade in affair. 

[hellraiserDLX]

This sounds like I should send mine to twotired when he seals the deal

I expect Scottly is way more interested in getting your business than I am. 

If I do it, it will likely be a trade in affair.

Well I'm not sure what I woukd have for trade if it came down to it but what would you be looking for if that were the case?

[TwoTired]

This sounds like I should send mine to twotired when he seals the deal

I expect Scottly is way more interested in getting your business than I am. 

If I do it, it will likely be a trade in affair.

Well I'm not sure what I woukd have for trade if it came down to it but what would you be looking for if that were the case?

"Trade in" 
You send me yours and if in repairable/ serviceable condition, I send you one of mine with modifications already done to it.
That way, if I screw up a mod, it was on my cover, not a customer's.

I'll be the first to admit, I'm no businessman.  I've never been able to make a business that's profitable, or even self sustaining, for that matter.  I think I'm still a pretty good engineer/craftsman, though.  I just don't have a businessman skill set.

Anyway, I'd rather do trade-in than a "core charge" model of business.
I can't say when I'll get time to finalize the repairs/mods, though.  House painting prep is sucking most of my work time these days (along with feral cat control  ).  And I just can't do the 12 hour works days anymore.  Aging sucks.

[bwaller]

Today I checked both type covers thinking I might join in this conversation, but I don't have much to offer. There isn't much meat in the cover to tap for a good thread. There could be a lug welded on first but that would add to the cost. A 5mm tappet adjuster screw might be a good candidate. I agree with you Lloyd that marring the shafts would be bad, what about machining a slight flat section for the screw to contact. That would eliminate damage to the shaft. 

[scottly]

There isn't much meat in the cover to tap for a good thread.

I suspected that would be the case, but without having a part to inspect I couldn't tell. Machining the shafts alone would drive up the costs, and welding would blow the budget out the window...

[TwoTired]

Today I checked both type covers thinking I might join in this conversation, but I don't have much to offer. There isn't much meat in the cover to tap for a good thread. There could be a lug welded on first but that would add to the cost.

Really?  I thought it looked ok to me.  Which position(s) did you see an issue?  There is enough meat in the cover to support the shaft.  Where wouldn't a set screw fit?   These covers do wear oddly.  Some of the shaft holes only wear at one end. If the upper surface isn't worn on one end, you would only need a set screw for just the worn end, to restore shaft position and keep from further wear, as the set screw would effectively prevent shaft rotation.

A 5mm tappet adjuster screw might be a good candidate.

You mean as the set screw?  I had envisioned something smaller, like 2 or 3mm.  I think that's enough to hold it place.  Why would that be too small for function?  I agree a 5mm screw is too big for the available metal as cast.

I agree with you Lloyd that marring the shafts would be bad, what about machining a slight flat section for the screw to contact. That would eliminate damage to the shaft.

Agreed.  That is what I proposed in reply #11.  I wonder how big bur would be raised?  That would determine the needed depth of the flat section.

[hellraiserDLX]

Haha I missed the "in" part of that statement. The cat situation is probably the most important thing to the care of well I will keep my eyes open for an updated one and when you are done with house painting we can go from there Maybe. I have aaaaaalllll winter now haha

[bwaller]

I wonder about the smaller screw diameter because they will still need to withstand the rotational force as well. Using four longer shafts would be helpful, but if they were available, latter model covers would be as well!

It certainly is worth trying, I'm watching with interest.

[TwoTired]

I wonder about the smaller screw diameter because they will still need to withstand the rotational force as well.

My reasoning is that Honda didn't anticipate or expect the shafts to rotate in the cover.  I'm not sure why, though.  At any rate if oring pressure at the shaft end is enough to stop shaft rotation (I have my doubts about it's complete effectiveness), certainly a grub screw settled into a flat on the shaft will do the job with far more certainty.

I suppose I should acquire some screws for a future test, which means searching for the most promising tip style.  Any thoughts about tip type for the application?
Flat point
Domed point
Cone point
Cup point
Knurled cup point

A flat point may not scar the shaft enough to require a flat.
easiest to find I suspect will be the cup point  Which can probably be ground flat.

I don't favor the domed or cone tip, as they will certainly require a flat, in order to avoid scarring the rocker bear surface upon latter dissassembly.

A knurled cup point might not need Loctite.  But, I'm not sure where to find these.


If I do make the cover mod, it occurs to me I have no engines that currently need it.  All my operable Cb550s have the new style cover already.  Which is why the old cover mod has been on the back burner for so long.

Are there any volunteers out there to be a test subject?

[hellraiserDLX]

How long would you anticipate turn around time to be?

[Trad]

What would you need sent, just the cover and the rockers? Mine currently has no wear so it might be a good subject.

[TwoTired]

I was out so I bought set screws today.  Couldn't find metric.  So these are 10-32,  $5 for the 16.  I don't think the cover will care.     Would have been nice to keep it all metric, though.  I'll keep my eye out for them in future travels.

If the threat of rain becomes real, it will drive me indoors from house painting and I'll start drilling/milling one of my spare my worn covers.  Then I'll find out how long it will take and whether it's cost effective.  I suspect it will probably take me all day to do the job.  I'm known for accuracy, not speed, ha ha. 
I figure the day will come when there is no choice but to repair.  But, a late model cover is still likely the cheaper route at this time.

As for trade-in, if I need to flat the shafts, probably need to trade those as well.  The rockers should stay matched to the cam, so those won't be part of the trade-in.  The set screws I found are cupped.  We'll see how much they gouge.

I guess painting the cover is negotiable.  I'll need to fix my bead blast cabinet for that task on the one I have, I guess.  Domino projects. 

[RAFster122s]

My '74 is a likely candidate as it has a little over 30-35k. I have been afraid to pull the caps to look as the bike has been a off and on project since I got...mostly off. I have parts for an upgraded performance upgrade with a 605cc Henry Abe I was going to install along with a 650 cam. I want to know the difference in performance. So, I am willing to tear down twice.

How long are you wanting the trial/test?
Tell me more...

I wonder about the smaller screw diameter because they will still need to withstand the rotational force as well.

My reasoning is that Honda didn't anticipate or expect the shafts to rotate in the cover.  I'm not sure why, though.  At any rate if oring pressure at the shaft end is enough to stop shaft rotation (I have my doubts about it's complete effectiveness), certainly a grub screw settled into a flat on the shaft will do the job with far more certainty.

I suppose I should acquire some screws for a future test, which means searching for the most promising tip style.  Any thoughts about tip type for the application?
Flat point
Domed point
Cone point
Cup point
Knurled cup point

A flat point may not scar the shaft enough to require a flat.
easiest to find I suspect will be the cup point  Which can probably be ground flat.

I don't favor the domed or cone tip, as they will certainly require a flat, in order to avoid scarring the rocker bear surface upon latter dissassembly.

A knurled cup point might not need Loctite.  But, I'm not sure where to find these.


If I do make the cover mod, it occurs to me I have no engines that currently need it.  All my operable Cb550s have the new style cover already.  Which is why the old cover mod has been on the back burner for so long.

Are there any volunteers out there to be a test subject?

[RAFster122s]

Yes, I can confirm the shafts have worn holes. Guess I should have scooped up thst 78 cover on ebay a few days ago...
David