Topic: '81 CB650C top end oil leak

[snowfighter2]

Hey everyone, been ages since I was here. My old 750K is just a fond memory. Had my sights on a 2013 CB1100....then, my son asked me to buy his 81 650C!  Yes! It has a bunch of nickle and dime stuff that you'd expect from a 34 year old bike.  Nothing I cannot handle. The only major issue is an oil leak from the top end. My son and I replaced the o-ring seal on the cylinder head cover. That fixed one major oil leak, but there is still oil leaking. I have narrowed down to the 2 o-rings between the cylinder and cylinder head.  Does anyone have experience with this leak, and repair for it?

[Moffman]

As someone who just went through sealing and ringing my top end down to the base gasket I'd be more then happy to give you some advice and what parts you need but I'm at a bar right now so it will have to wait. Do you have any pictures of the oil leak

[snowfighter2]

Thanks Moffman, I will post pictures as soon as I can.

[Moffman]

Ok I have a '79 CB650 but from my understanding there shouldn't be any differences to the motor besides CV carbs. Oil leaks could be possibly the six rubber pucks that cover the head bolts. There is also the head gasket and two o-rings between the head and block.

Personally I just wanted to reseal everything to avoid the guess work. I'd recommend OEM parts over the aftermarket top end kits. I got a kit from david silver spares by NE Gasket and the head gasket was so poorly made it wouldn't even fit on the dowels correctly nor line up with bolt holes. I'll edit in all the part numbers you need tomorrow as I don't have them on this computer.

I ended up removing the cylinders, breaking a cylinder fin, getting it welded, replacing the base gasket, breaking a ring, honing and re-ringing but if you are just sealing the top end you shouldn't have to take off the cylinders unless you break the seal on the base gasket which takes a decent amount of force. 

Here's some pictures of my journey to give you an idea: http://imgur.com/a/x9yyF

[snowfighter2]

I believe you are correct about the similarities of our engines. My son and I did seal the valve cover (cylinder head cover) with that huge o-ring seal AND the six pucks. We ordered OEM Honda parts from the local dealership. I am pretty confident the leak is at the 2 o-rings between the cylinder and the head.

Awesome pictures! Yep there is that pesky little $3.00 o-ring! The concensus here is use OEM gaskets and seals. I would have to agree. No sense tearing into a motor just to reassemble it with substandard parts. I take the same approach working on my cars and trucks. You get what you pay for when it comes to repair parts.

Again, the pictures are awesome and very helpful. I will be sure to take plenty of before and after pics of my journey into the head of the Honda!