Topic: 550 rocker cover fix

[BomberMann650]

Adding a sleeve and a set screw seems to be the shared idea.  Just a matter of making it a practical repair.

[TwoTired]

Upon first encounter with a worn cover, I had thought a sleeve bushing was the best solution.  The cutting head needs to be a pretty long machining rod to reach all the surfaces, which leads to a support of the cutting bit head issue.  Normally, to make a hole bigger, I use the existing hole as a pilot surface to hold the cutting head/reamer.  But, with an oblong hole, keeping it centered might be a challenge, particularly when you reach in from the end and get near the chain tunnel.
Ironically, it would be easier to bore the hole bigger for a bushing on a cover that doesn't actually need it. 

I couldn't find any off the shelf tooling to bore a hole that deep, either.  But, I might not be looking in the right place.  I'm just an amature machinist.  Later I thought of the set screw possibility.  But, I'd rather have a repair that was invisible from outside the motor.

When I last addressed the worn one, a new cover kit was still available from Honda.  So, I used that instead of reworking worn ones.  I also bought a couple 77-78 covers off eBay for my fleet.  So, doing a refurb cover went on the back burner.

Cheers,

[scottly]

I think the most viable option is set-screws, but to make it economically feasible would require a certain amount of investment in tooling. In other words, the first part may cost $600, but the following parts may only cost $60 each, just for example...

[dave500]

im in the "just find a locked type shaft one"?mind set,if you have a minimal wear one its worth dinking with it,if you can grub screw it itll be better than nothing,it aint like these are super rare and every single one is worn out?

[BomberMann650]

We've had this discussion ad nauseum 

[calj737]

I couldn't find any off the shelf tooling to bore a hole that deep, either.  But, I might not be looking in the right place.  I'm just an amature machinist. 

An idea for you, Lloyd, using a reamer (best idea in my opinion) do only half of the cover from one direction. Then flip the cover, and do the other half. This eliminates the rigidity issue of an extra long reamer. Using a collimator, you can level the cover exactly again once flipped, and if you’re equipped with a DRO, you should be fine.

I’ve bought reamers through MSC Direct in exact sizes and found them to be very reasonably priced.

[Lostboy Steve]

Fellas, fellas!  We're all friends here!

One day I'll get off my arse and mail some dead heads to lostboy and we'll see if there is a cure for the curse!

This is all your fault cow. I could have been well on my way to permanently fixing a rocker by now.


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[Lostboy Steve]

I have a very good friend who has an R&D style machine shop. That's the only reason I offered to work up a solution.

Initially I was only going to repair the bad ones which seem to be left side intake on the few I've seen that are bad. I have already sketched a few ideas and taken others ideas into consideration. For my own rocker if I ever get the time and space to pull it off, I was going to use a single one piece shaft that is enlarged in the cap area. The actual cap area is still round so that can be used to center the cover. Anyway some semblance of a cure is on its way.


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[TwoTired]

I couldn't find any off the shelf tooling to bore a hole that deep, either.  But, I might not be looking in the right place.  I'm just an amature machinist. 

An idea for you, Lloyd, using a reamer (best idea in my opinion) do only half of the cover from one direction. Then flip the cover, and do the other half. This eliminates the rigidity issue of an extra long reamer. Using a collimator, you can level the cover exactly again once flipped, and if you’re equipped with a DRO, you should be fine.

I’ve bought reamers through MSC Direct in exact sizes and found them to be very reasonably priced.

The reamer was my intention.  Note, that the shaft holes do not pass through the cam chain area.  So, I think the method you suggest is the only way to enlarge the elongated holes.  It would be four drill/ream operations, at a depth of some 6-7 inches.  Still no support for the cutting head end, and the oblong holes will tend to place side pressure on the cutting end to have an offset hole in deep.

I don't have a collimator.  Will have to research that.  Don't have a DRO either.  But, I do have plans to add one to my lathe/mill/drill.

I did briefly explore using a single shaft for the rocker upgrade "kit".  But, it was too long,to fit into the old covers.  So again, it needed to be drilled, 7" deep.   I couldn't find a cutting method that deep, off the shelf.

Then there was the bushing material to locate and press in (straight without distorting/cracking the cover), in short sections for each shaft bearing position (16).

That's when I sought alternatives and the set screws came to mind to push and hold the existing shafts back in their original positions.

Cheers,

[TwoTired]

I have a very good friend who has an R&D style machine shop. That's the only reason I offered to work up a solution.

Initially I was only going to repair the bad ones which seem to be left side intake on the few I've seen that are bad.

I have an example cover that was used well after the left side intake shaft holes went oblong.  There are positions for 2&3 cylinders that are also oblong.  Just fixing the outer intake shaft positions will not be a complete cure, imo.  Each and every floating rocker shaft has the ability to rotate and wear the cover.  Some positions just wear faster than others for reasons I do not fully understand.

Here is a pic with the right end worn, as well as the left.  Positions with 2&3 rocker shafts worn are present in this example, too.

Cheers,

[Lostboy Steve]

I have a very good friend who has an R&D style machine shop. That's the only reason I offered to work up a solution.

Initially I was only going to repair the bad ones which seem to be left side intake on the few I've seen that are bad.

I have an example cover that was used well after the left side intake shaft holes went oblong.  There are positions for 2&3 cylinders that are also oblong.  Just fixing the outer intake shaft positions will not be a complete cure, imo.  Each and every floating rocker shaft has the ability to rotate and wear the cover.  Some positions just wear faster than others for reasons I do not fully understand.

Here is a pic with the right end worn, as well as the left.  Positions with 2&3 rocker shafts worn are present in this example, too.

Cheers,

I had also intended on using a single shaft in place of the pair even on the good ones.


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[Gene]

This is the most entertainment I've had in a while. Thank you all.

I replaced my worn cover with one not worn and employed the O-ring bit. Only time will tell if it works. #1 intake - yup.

[RAFster122s]

If you had a long shaft capable of reaching farther than from one side of the cover to another after drill a hole through the tunnel you could slip the bit in from the side you wish to machine  and the cutter could be drawn back through the cover to cut the cover oversized path. To do it half way and then flip you would need bushes to slip over the shaft in the newly cut holes to support the shaft while doing the opposite side. If you are doing it completely from one side to the other replacing all the shafts.  Heating the cover to do the inserts but the fit would be less than 1 thou to prevent a crack in operation between the bushing and the cover.  Or it is a friction fit and you glue in the bushings or set screw them into place.  Pinning the shafts from inside the underside of the cover could make it  a nearly transparent repair without removing a cover.  You would likely need to rtv or plug the holes to the cam chain tunnel. An oil stable plastic plug could be popped into the holes with a thin film of rtv to seal the oil from wicking through.  Bringing the cutter through slowly would lessen deflection, or you do it in small nibbles reaming/cutting the holes to oversize for the bushings. The shafts are not having an oil passage to lub the shaft in the cover, are the rocker arms and shafts seeing an injection somewhere?  I have not looked at a cover of late...
David

[TwoTired]

Has anyone found suitable bushing material?

Does this have to be fabricated, too?


Cheers,

[RAFster122s]

Sized to fit would require a bit of lathe work and I was thinking that bronze being the appropriate material.
You know the size of the ream or milling bit, so you shpuld be able to have it made in advance.  If tool steel ejector pins that are nitrided would be suitably hard for a replacement shaft.  So, you then just calculate the tolerance needed for the bushings.

[ts354]

I have a 550 apart right now, wondering what I needed to do to it to make it a reliable and maybe a little bit stronger bike.  I started going down the rabbit hole of should I buy new valves/guides/rocker arms etc, etc......  Well after reading all the above, why would I spend a lot of money on these things?  I think I will just clean everything up good, hone the cylinders lap the valves and clean the carbs and slap it all back together and just not worry about anything.  When I started building this bike I bought a spare 550 engine.  The original was a 76 and the spare was a 74.  Guess which one got stolen from my storage unit? yup the 76.  From the looks of things, the way these engines were built, they are pretty much a one time use type bike engine.  Meaning, yes you can rebuild them but they were not designed to be rebuilt a bunch of times.  They were designed to sell to the public in mass.  They aren't bad bikes, just regular ole bikes.  I just want it back together, not smoking, running smooth, so I can ride it.

[RAFster122s]

If you do not have rocker shaft wear dropping a 650 cam in gives you a nicer torque curve and powerband with no changes needed to pistons, etc.  Likely will need to cut some clearance reliefs for the cam lobes.

Hondaman recommended a 1st over is a means of restoring 5-10% power back because the metal surrounding the cylinder liner making up the cooling fins allowed them to shift and move a bit during heat cycling after operational.  That robs the bike of power.  Align boring the cylinders restores that lost power.  No worries about this drift as it only occurs once, you will not need to do it again.  You will need to make sure it is align bored and not just a bore job, small setup difference and few more measurements when boring is not happening by a cnc machine...they should be setup to align bore by default, but you never know.
Mark also outlined basic perf enhancements easy to do for a tad better perf while having one opened up.

If your cam cover has rocker shaft wear you will be wasting money on a good cam unless that cover is replaced with a good cover.  Same is true for rocker arms.  Usually you will not see significant wear on cam or rockers if the motor didn't have issues.
Oil starvation will roast a cover/head/cam/rocker arms, etc
Cover wear kills the cover of course but also the cam, rocker arms and usually rocker shafts.

[ts354]

No.1 and No.4 intake rocker arm shaft holes are wallered out.  Anybody got a good rocker cover you want to sell? 

[Lostboy Steve]

Has anyone found suitable bushing material?

Does this have to be fabricated, too?


Cheers,

Bronze and yes. 


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[RAFster122s]

Ts, wrong thread to ask for one when most hear are looking to see if there is a way to fix.  Try the wanted section to post a wanted listing.  Or, go shopping on ebay.

[titan joe]

So this is the reason why my #1 intake valve lash adjuster is screwed really far in to get it set right? And why the rocker and cam show uneven contact?

[TwoTired]

So this is the reason why my #1 intake valve lash adjuster is screwed really far in to get it set right? And why the rocker and cam show uneven contact?

Well...  Those ARE the symptoms.

Cheers,

[titan joe]

Good to know

@Lostboy Steve: I have a spare cover I can mail your way. I think that the one on my bike is in worst shape, but I've only begun to learn about this issue. I may swap it with the one on my bike just to see which one has more life and just in case nothing comes of this. Would you want the cover fully loaded with rockers and shafts or just the plain cover?

[titan joe]

I'm going to take mine down to my machinist friend hopefully tomorrow. The one on my bike was very very bad. One idea I thought of was has anyone drilled a hole to lubricate the bore? All the rocker arms are lubricated from the camshaft splash. There is a hole on the top of the rocker arm. Has anyone tried putting a similar hole for oiling the bore in the cover? **Edit** only possibly helps a cover that's in good shape, not much of a repair like what this thread is about.***



Like in that location. I would think that this is more of a lack of lubrication problem. There really is no provision for supplying oil to the pin bores in the cover. That's what I think, so that's why I ask if this has been tried. The aluminum journals for the camshaft stay happy.

[dave500]

theres plenty of oil there,its the spring pressure that dosent help.