Topic: 79 CB650 top end rebuild

[taso]

I am working on getting a 79 CB650 running.  One part of this project is a head rebuild.. didn't want to, but one of the plugs sheared off flush in the head, so I decided to pull the whole head to try to extract it.  If that doesn't work, I ordered a spare from ebay which should be here soon.

I have 2 specific questions:

1. I ordered a set of Athena top end gaskets from BikeBandit.  The package says CB650 80-83.  Are these ok for the 79?  I did a general internet search this morning and it seems they are sometimes also sold as "79-82".  So if 79-82 are compatible, then 80-83 should also be compatible?

2. While taking off the head cover off, murphy's law (and stupidity) hit me hard, and I accidentally dropped one of the small washers right into the slot where the cam chain lives!  I tried fishing for it with a magnetic pickup tool, but the head of the tool is too wide to fit through the bottom of the slot, where the washer ultimately fell.  I was thinking along the lines of trying to flush it all the way down into the oil pan or oil filter area by pouring more oil through.  I was wondering if someone with intimate knowledge of the anatomy of this engine might have some ideas on the best course of action here.

[Hush]

That wee washer will probably end up lying under your bigend, it could lie there for years with no problems but it could also get the idea that moving around is cool too, not sure what you should do for the best there, it may be possible to flush it out.
Being a lazy bastard I'd probably leave it there and cross my fingers.
Have you downloaded the 79 650 manual from this site, it will show the crankcase layout.
It appears there is a ridge between the mains and the gearbox that may stop you washing that washer out via the sump.
Scunny or Mannjisan on here might have empty cases they could look at to give you a better answer.
I'm doing the head gaskets on my 79 this winter so I'd be interested in any problems you strike.

[MickeyX]

1st, I think you need to find out if your set of gaskets is for the 79-80 SOHC engine or the 83 and after DOHC. As far as I know, there is no gasket set that fits the years  your package says it does.  

Soos? Kit? Hush?

[scunny]

will look into my motor tonight and let you know where your washer may go. as long as the athena kit is sohc your good to go.

[paulages]

"flushing it" is probably not likely, unless you have a solvent tank (with petroleum based solvent) and can put the engine in it and flush the solvent through the tunnel. even then, you'd want to be really careful to get all the solvent out or you'll have some really thin oil on startup. it'll be hard to shake it loose, because it will stick to oil in the bottom of the case. if it fell straight down, you might be abele to fish it out through the bottom with the oil pan and primary chain removed. good luck though... i dropped one down there once, and after splitting the cases found it in a crevice behind the chain oiler.

[scunny]

as paulages said, you might get lucky, just had a geeko at my internals and it's a busy place there. still wouldn't hurt to drop the pan and have a fish around with a magnet.

[cb650]

79-82 gasket sets are the same.   The 83 might be a typo or as I suspect some countries might have gotten the sohc 650 until 84. Would explain the haynes manual.
Yes drop the pan and make a best attempt to get the washer.

[taso]

Thanks for the advice everyone.   

I'll be working on the head over the weekend.  I'll do my best to extract the washer and follow up here.  If all the stars are aligned I should have the head and carbs back on the bike and potentially fire it up before the weekend is over.  Boy will that be exciting.

[taso]

Just to follow up - I got the bike to start last night!!   Never did get that washer out ..  turns out it's not even magnetic.      I just have to keep my fingers crossed that nothing catastrophic happens.  *gulp*

The next issue I hit after the motor and carbs were reassembled was that I had no spark on 2 and 3.   The manual made it easy to diagnose that the issue was in the pulser generator and the spark units.  Replaced all 3 from ebay and now it fires up, idles, and revs pretty decently.

Next thing to tackle is an apparent clutch issue. 

Hopefully get this thing on the road for a test ride within a few weeks!