Topic: CB550 Cylinder Head Compatibility

[Nabors12]

Just started a restoration on a 1978 CB550 and immediately ran into my first issue. While removing the spark plugs, one of them broke off in the head. I used an easy-out on it and needless to say, it broke off inside the plug. I'm thinking I will have to find a new head and was wondering if the cylinder heads from other years were compatible with my 1978 550K, for instance a cylinder head off a 1974 CB550 KO?

Thanks

[turboguzzi]

a good machine shop should be able to remove it

in any case, you could use a 500's head too as well as other 550's,  no significant differences.

[Kong]

I can not possibly picture in my mind how a person manages to "break off" a spark plug, nor can I envision even finding a way to get an easy-out into what might be left of the plug although everyone who's ever owned a set of easy-outs knows how easy they are to break.

Is there any chance at all you have a picture of this mess?  I'd really like to see just what it is you have to work with.

[Nabors12]

Despite how I feel your response may have been a little condescending, since breaking ancient spark plugs in half in engines found in barns is not rare, here are some pictures.

[Kong]

Sorry to sound condescending, that certainly was not my intention.  I really was wanting to know just what had happened.  To be honest with you, I've broken my share of porcelain tops, but I've never seen one rung off at the base like that.  You know, if the easy-out - which must be a pretty hefty one - is still stuck in there you may be able to concoct a way to not try to back it out, but maybe be able to continue to screw it right on though into the combustion chamber and out; that is with the head off of course.  With the tap broken off I don't see how you can avoid taking the head off.  Once that's the case I'd take it to the local machine shop myself and act real nice to the proprietor.

That is one hell of a thing though, first time I've ever seen it.  I wish you luck.

[TwoTired]

Perhaps this is a good lesson on why the Stock Honda toolkit Spark plug tool works so well.
Notice the bell design which easily clears the obstructions in the access tunnel.

Yes, you can find thin wall sockets that will work.  But, none do a better job on the spark plugs for inner cylinder 2/3 access, without introducing side loads on the spark plug base.

Cheers,

[Duanob]

If your taking the head off anyway I say go the machine shop route. And while you're in there have them clean it up a bit and replace valve guide seals have your valves lapped and whatever other work needs to be done. It doesn't cost that much and it will seem like a new motor again.

[Nabors12]

Thanks for the replies. I have begun breaking down the head and should have it all taken apart tonight. Whoever's idea it was to put screws on a head assembly should be shot, luckily I bought an impact driver and mallet that made them come out easily. Definitely going the machine shop route if I can get it done for a reasonable price. Really don't want to go to crazy since I found an old head online for 50 bucks, although since you pointed out the possible issues with the earlier model heads I may get it machined regardless.

[Stev-o]

I cannot imagine working on a CB w/o an impact driver.

[TwoTired]

FYI, cylinder head cover and cylinder head are two different parts.  The 78 should already have the upgraded cylinder head cover (cam cover).

[Nabors12]

Update on my progress with pictures, cylinder head has been pulled. Thank goodness for this forum when it came to separating the head, those two pry spaces that Honda added were genius.

Any comments on the state of my cylinders is welcome. 

[Duanob]

Can't see super close but it looks like a good cleaning, valve lapping, and replace all rubber and gaskets and you're good to go. There are rubber guide seals just below the valve springs that get old and brittle. How are the valve guides? Sloppy? tight?