Doms CB550F1 project

[DomP]

Depends what you mean by throttle stops

I've just got a Haynes manual today which says 56mm. This is what I was referring to Ken

[DomP]

I think this engines not well, far too much blue smoke and I can't get the it to idle well enough to balance the carbs even. I just can't work out what to do next.

[Oddjob]

Strip the head and barrels off.

[DomP]

Strip the head and barrels off.

Yes I think so Ken, to be honest it's got an oil lea from the head gasket that needs sorting so I'm going to be going in there at some point so might as well now.  Also a few times after turning it off the exhaust has made a king of vacuum stuck back noise, what's that?

[Oddjob]

Sounds like either a bent valve or a really bad valve seat problem, so it's pulling air down the exhaust due to the poor seal.

Don't forget to replace the valve stem seals whilst you have the head off.

I suspect you'll find rings stuck in the grooves on the piston as well

[DomP]

Ken, do you remember offering any more help I might need? 😉   I might be asking a few questions

[Bryanj]

Its either been stood too long with a valve open, or the cam cover has not been reassembled to the head carefully enough and a valve stem got bent!

[DomP]

Someone's been in there before me, theres dodgy red gasket sealant on the cases which can't be a good sign.  I've never fully stripped an engine before, now I know you are all going to say pull the whole engine and strip it fully but could I pull the head and barrels in the frame and see what I find before going any further.

[Bryanj]

Yup, its easier to do that way as it makes the lump lighter.
The full honda 500/550 manual is in either Ashs dropbox or alladins cave so download it and read, especially the bit about refitting cam cover!!!

[Trigger]

If any valves are bent Dom, get a magnify glass and check that non of the valve guides are cracked. Even a small hairline crack will open up once the engine has warmed up 

[DomP]

Thanks all, I've got the rocker off following several guides, I'm labelling everything and sticking bolts through labelled card to remember their positions for reassembly.   I'll post some photos later

[Trigger]

Thanks all, I've got the rocker off following several guides, I'm labelling everything and sticking bolts through labelled card to remember their positions for reassembly.   I'll post some photos later

I love pictures of the insides of engines. That is what made my job so interesting, you would never find the same problem once stripped down 

[DomP]

For now in going to call it a day, the head won't come off the barrels and it's beer o'clock

[McCabe-Thiele (Ted)]

My 400 head was well stuck on Iirc I sprayed all around the edges of the head gasket with Plus Gas then used a big Rubber mallet to give it some side shock. Lastly I used a plastic double glazing wedge to persuade it to separate.

[DomP]

Here's what I've found so far...  the rockers are nice and clean but there is some scoring to the surfaces in the head and on the camshaft, some is visible but can't be felt with a nail.