Topic: Prep for top-end; advice & issues w/ value cover

[bmcdonou]

Hi all,

First time owner of a '75 550 engine sitting in a '73 500 body. I got the bike last spring and noticed small amount of oil leaking from the left side, towards the top. Totally ridable, not even enough to need oil top off. On longer rides, would eventually drip/burn off and smoke a bit, but nothing too major.

Now that it is winter I am prepping to do a top-end gasket change, and looking for some advice. Unfortunately, I live in a highrise and don't have access to a garage where I can dismantle slowly and just figure out as I go. Rather I am considering a DIY garage and so will have to pay a day or week rate. So I need to be calculated and exact - and get it right so I can successfully ride home. As such, I've been reading all the manuals, posts, and watching videos that I can find. But I do have a few questions and unfortunately found some issues already that has me concerned.

Here are my questions:
1 - Recommended kits for sale here in US? I have found ones at Common Motor Collective, but it is a full engine vs just top-end. There is also 4into1 which sells just what I need, but unsure on quality.
2 - Major mistakes newbies make, so I can be extra cautious about them? I've already ready about bending the value arms when removing the cover (as I will be doing in the frame) as well as missing the hole where the cam-chain tensioner goes into...anything else?
3 - Any other tips or tricks to help go smoothly / successfully? I've read about using 'hondabond' on the outside edge of the cover gasket. loosing the values and fixing up w/ rubber bands. using wire hook to stop cam-chain from falling into bottom end.
4 - Anything you would recommend to have purchased ahead of time just in case? I am already gong to purchase new allen-head bolts as I can see some are close to being stripped. Would you recommend having a set of piston rings just in case? Anything I should just replace while I am in there?

Lastly, when poking around I found some issues I did not see when purchasing the bike. First, it seems that one of the breather cover fastenings has chipped away on the head cover. It is super hard to see until I got my face right into it (pictured). I cannot tell if the bolt threads are still w/in the breather cover, so I may have to drill out to remove. Also I noticed some liquid gasket on the left side head cover seam and followed it to under the side cover. There I found more and also it seems a small chip at the seam (about the side of a flat head screw driver), but I can actually see the gasket. So, any thoughts on repair or is my head cover toast? Would prefer to keep it as the PO has it chromed and frankly I like the look. But, if it is pointless to try and patch/repair, then I may try to source a replacement.

[bryanj]

Only repair foracam cover with edge chipped is a different one, all 500/550 will fit 77/78 had modified cover to stop rocker spindles turning.
Common missed leak is the soft wasers on the bolt holding the right angle brackets the end caps screw to.
Not all sets have the rubber pucks between head and cam cover.
You need 0.2 mm thicker O rings for the head gasket.
As a mechanic i refused to leave the cylinder if head came off to ensure no oil leak at base.
Only difference between 500 and 550 sets is clutch cover gasket
Its when refiting cover you can bend valves and you cant change all the screws for cap bolts or you wont get a couple of tappet caps back on

[middletons]

IMHO, If all you need is a new valve cover and to fix those two leaks on the sides, don’t do a whole top end job. If oil is leaking from the rocker shafts on the sides and/or because of missing aluminum washers described above, just fix those issues. You can make things a lot worse by fixing what ain’t broke.

[bmcdonou]

Only repair foracam cover with edge chipped is a different one, all 500/550 will fit 77/78 had modified cover to stop rocker spindles turning.

Good to know. To clarify, are you saying ALL 500/550 cam covers will work, even the modified 77/78, or that all will work except the 77/78 given the modification.

As a mechanic i refused to leave the cylinder if head came off to ensure no oil leak at base.
Its when refiting cover you can bend valves and you cant change all the screws for cap bolts or you wont get a couple of tappet caps back on

I have heard this advice as well, which is why I reserved myself to do the entire topend. I know for sure there is a leak at the cover seal; that is obvious. I've done a couple clean and rides to see if I can tell if the header seal is also leaking; it is hard to tell, if it is it is slow. The cylinder block seal to the base is not leaking, i'm certain. But given the advice you mentioned, figured I'd do all (tho still on the fence).

Good call on the cap bolts, had not though of that. It looks like there would be clearance, but I think you are right. I'll see if I can source new screws then.

IMHO, If all you need is a new valve cover and to fix those two leaks on the sides, don’t do a whole top end job. If oil is leaking from the rocker shafts on the sides and/or because of missing aluminum washers described above, just fix those issues. You can make things a lot worse by fixing what ain’t broke.

Admit I have fear about this. Given this is my first time, I don't have my own garage where I could take time to troubleshoot, there is part of me that just wants to do the cover. The other part of me says do the topend so you know it's done.

I may do a really good clean and run the engine and see if I can confirm w/o doubt that the cylinder head to base seal is not also leaking. If >90% certain, I may take the easy way out and just do the cover. And, I can probably do that in my highrise garage late at night w/o anyone knowing (not supposed to work on vehicles in garage).

[middletons]

I can tell you for sure that all years 550 covers will fit. the 77-78 are better because of the redesign. I'm not sure about the 500 version. If it were me, I'd hold out for a 77-78 version because you can be relatively sure the part you get won't be damaged/worn out already. Sometimes used earlier versions can have enlarged rocker shaft holes.



There are 3 major gaskets in the top end; valve cover, head, and base. any one of those could leak oil. if the head or base is leaking, you gotta consider doing the whole top end.


You can use the hex bolts by the tappet covers, but you have to sand the tops down to make room.

[jonda500]

removing and replacing the cylinder head will not make the cylinder base gasket magically start leaking!
John

[bryanj]

It will if the cylinder block moves which it frequently does

[bmcdonou]

There are a few options on ebay, but looks like I may be playing roulette on quality. I see a few that are covers and heads as a set. Were these manufactured together; any reason to need to buy the 'set' for better matching mating surfaces, etc? Or all good to buy a cover and match with my existing head?

[middletons]

You only need the cover.

[flatlander]

if you get a later cover with the fixed rocker shafts (77/78), then you will also need those shafts and the pins that keep them in place. unless your engine already has one of the newer covers, of course.

[bmcdonou]

Thanks. Is there any documentation or pictures that show this difference? I've searched online but have not been able to locate anything. Just so I know what I'm looking for.

[flatlander]

the later type cover has 4 additional bolt holes compared to the earlier one.
there were some pictures posted here on the forum of the two types of cover. if you do a search they should turn up.

[bryanj]

There was a sevice bulletin on the board somewhere

[flatlander]

here's a pic of the later type: