Topic: Top End Rebuild Question - Cylinder Head Cover CB550

[campbmic]

Hello! I have a 1975 CB550K1 and just finished replacing the gaskets on the top end. I followed the manual for setting the timing. However, when I try to put my cylinder head cover (the large piece that covers the cam shaft and valves - not the breather cover) on it doesn't seem to sit flush. Theres a gap thats a couple cm on one side, I'm guessing thats from the valve not being compressed but wanted to ask to be sure. Is it ok to go ahead and tighten this down to spec? Or should this be flush and I messed something up?

Heres a link to the pic: https://imgur.com/a/wviGrRl

Also, the engine is at TDC and right now all the tappets have wiggle room, except for #1 on the intake side and #4 on the exhaust side. Does this sound right? I thought 1&4 fire at the same time so I would think they should both be open or closed together but wasnt sure.

Lastly, I was dumb and have mixed up the screws/bolts that tighten the cylinder head cover and possibly have some other screws/bolts in the mix. The manual just calls them 6mm bolts but doesnt specify the length and there's a bunch of different lengths. Does anyone have a resource showing which screws/bolts go where?

Thanks and I appreciate any help!

[TwoTired]

If you have the Honda shop manual it warns about correct cylinder cover installation.  The warning is about tappet alignment with the top of the valve stem during installation . If engaged to the side of the valve stem, tightening down the cover results in bent valves.  And this will also block proper cover fitment.  Sounds like you have already tightened it down with misalignment, likely bending a valve, and now needing head work.

[dave500]

if you havent fitted it yet back the tappets all the way loose.

[campbmic]

If you have the Honda shop manual it warns about correct cylinder cover installation.  The warning is about tappet alignment with the top of the valve stem during installation . If engaged to the side of the valve stem, tightening down the cover results in bent valves.  And this will also block proper cover fitment.  Sounds like you have already tightened it down with misalignment, likely bending a valve, and now needing head work.

I joined this forum back around 2010 and you helped me a ton then! I appreciate all of the help you gave me and glad to see you're still helping us with limited brain cells! Once I noticed the cover wasn't sitting flat I stopped to ask for help so I haven't tightened anything down aside from the cylinder studs. I'm using the shop manual at page 31-32 and didnt see any warnings but I might not have understood correctly.

I can see each tappet is lined up with where they push on the valves to open/close (i.e. its not misaligned from what I can see). The screws for the cover (seen in one pic) are just lightly hand threaded since I'm trying to figure out what hardware goes where.

Photos: https://imgur.com/a/CXzIGUt

Any resources or advice on the proper procedure for doing this? I really didnt see much in the shop manual about installing the cover but maybe I missed something. I assumed the gap was from a valve needing to be pushed down but stopped just out of caution. Not sure if I'm supposed to rotate the crank to a certain position or how to do it.

Thanks,

[campbmic]

if you havent fitted it yet back the tappets all the way loose.

Thankfully I havent tightened anything down aside from the cylinder studs. I adjusted my valves a long time ago but dont remember much about it. Are you saying to undo these nuts and back out the screw on all of the valves?
Photos: https://imgur.com/a/CXzIGUt

[Scott S]

 Use the rubber band trick to hold the rocker arms up.

http://forums.sohc4.net/index.php?topic=82508.0

[campbmic]

The tappets all seem to be lined up properly. The engine is at TDC and it seems like #1 and #4 tappets are making contact with their valve stems.

[jonda500]

After undoing the locknuts and backing right off all the adjuster screws (and making sure they all engage properly with the valve stems) you will find that the cover is still held up a little in places (by some of the valve springs needing to compress a little) - this is normal.
I like to gently snug up the bolts/screws finger tight to hold the cover down where it's not held up, then rotate the engine until the cover comes down flush (sometimes I have to repeat this process) before doing the final tighten down.
A parts list would help you work out which screws/bolts go where, or just keep swapping them around until they all poke out the same amount before starting to screw them in. The two end bolts have special aluminium crush washers under the end cap brackets to hold the oil pressure in.
John

[campbmic]

After undoing the locknuts and backing right off all the adjuster screws (and making sure they all engage properly with the valve stems) you will find that the cover is still held up a little in places (by some of the valve springs needing to compress a little) - this is normal.
I like to gently snug up the bolts/screws finger tight to hold the cover down where it's not held up, then rotate the engine until the cover comes down flush (sometimes I have to repeat this process) before doing the final tighten down.
A parts list would help you work out which screws/bolts go where, or just keep swapping them around until they all poke out the same amount before starting to screw them in. The two end bolts have special aluminium crush washers under the end cap brackets to hold the oil pressure in.
John

This is exactly what I thought was going on but wasn't sure. After learning the hard way more times than I'd like to admit, I decided I should stop and ask around.

TwoTired and Dave500 have more knowledge about Hondas in their pinky, then I will ever have so I'm still a little hesitant. I guess I'll rotate the engine until it sits flush, tighten it down, then slowly rotate to make sure somethings not jamming up. Thanks Jonda!

[jonda500]

The aim is to limit the amount of stress on the fragile threads in the aluminum head by not using the bolts/screws to compress the valve springs and not trying to screw them in with the held up cover holding them crooked in the hole.

Cylinders 1&4 plugs spark together every rotation of the crankshaft and their pistons go up and down together as do 2&3, but the firing or burning fuel only happens every second rotation so one of the sparks is "wasted" in this system with the points cam running at crankshaft speed. If the points cam was up on the camshaft (which turns at 1/2 of the crankshaft speed) then there wouldn't need to be any wasted sparks.
John

[campbmic]

The aim is to limit the amount of stress on the fragile threads in the aluminum head by not using the bolts/screws to compress the valve springs and not trying to screw them in with the held up cover holding them crooked in the hole.

Cylinders 1&4 plugs spark together every rotation of the crankshaft and their pistons go up and down together as do 2&3, but the firing or burning fuel only happens every second rotation so one of the sparks is "wasted" in this system with the points cam running at crankshaft speed. If the points cam was up on the camshaft (which turns at 1/2 of the crankshaft speed) then there wouldn't need to be any wasted sparks.
John

I backed out the tappets and the cover was flush. I'm going to order some new screws/bolts before I tighten it down. Thanks for all the help!

If you don't mind I have a couple other questions:

1. On the camshaft there is a "screw gear" on one side. I dont know if its called a screw gear but its basically grooves in the cam shaft that look like a screw. I'm 99% sure this is for the tachometer. Can you confirm thats right? I just want to make sure I have the camshaft in the right way.

2. I think I understood what you said about "wasted" sparks. When my engine was at TDC it looked like the valve of #1 on the intake side and #4 on the exhaust side were trying to close (didnt have any wiggle room which prevented the cover from sitting flush). Does that sound right? I assumed #1 and #4 fired at the same time and should be open/closed together so I was thrown off when #1 was opening intake and #4 was opening exhaust, but I think thats what you're getting at with the "wasted" spark cycle. I just wanted to be sure.

Thanks again!

[dave500]

yeah thats the tacho drive gear on the cam,also tighten those very front screws on the cover last!dont pull down on them till the cover is completely flat on the head,those little ears they go through snap off so easy!,and dont torque the 6mm bolts down,just feel em down snug,check em once the motors been hot n cold few times.

[dave500]

as an aside having the points operate from the crank makes for a prettier motor!no bulge on the rocker cover one or either side!wasted spark is common on even cars,its not detrimental at all nor an improvement to ignition,its just an easy way to achieve it mechanically.