Topic: CB650 Cover Leak

[London Dock]

Hi guys,

So as of last fall I'm the owner of a '82 CB650 (standard); has about 30k km on it and paid $800 Canadian dollars. Thanks to your forum, I've successfully completed some repairs including a faulty rotor replacement and fixing a rear brake light switch (now charging wonderfully!). Also just recently put a new seat cover on from Sargent cycle, so I will post some pics soon. My last issue is a small oil leak coming from the cylinder head cover around the two most extreme flange bolts on the left and right sides. These would be parts 25 in the picture.

I'm wondering if this is due to those two little magic o-rings I keep reading about down further in the cylinder head. It doesn't seem like it to me, as after a good cleaning and one ride, the oil visibly wetted the area around the head of the bolt and running down the larger cooling fins of the cylinder head. Do I just need to replace the sealing washers? Thanks!

[Frankenkit]

does it look like it's coming from the tops of those bolts?
I'm tempted to say "they all do that" but it's only partially true. there are tiny crush washers that help seal that, too.  new washers might help. I dabbed RTV under the washer, too, to help seal and it seems to have worked. HTH.

[martino1972]

welcome crazy guy....canadian? what part..


okay...first off,the magic little o-rings sit between the cylinders and the head and you will see it leaking from between that area on the side of the engine (see first picture) (second picture  shows where those o-rings go)   
But that doesn't seem to be your problem.....you will have to take the offending bolts out and either replace the seal washers or like KIT said,put some rtv or gasketmaker on em....





 

[London Dock]

Kit, the leak is coming from around the bolt area, just underneath the washer. The RTV sealant is a good idea...I guess I should hall the tank off to check the other bolts with sealing washers as well  .

Martino, thanks for the pictures! It's definitely not in that location, but the upper fins on the head (the clean fins in your first picture). I will upload a pic tomorrow morning, as I am heading out to upgrade my motorcycle license and will be riding up to get it ! And FTR, I'm in Kingston, Ontario...never been to AB but always wanted to see and travel the mountains...

[Hush]

Woohoo another CB650 owner, welcome to the land of the confused.
So you swapped yout rotor over and your charging returned to normal, me too...even tho the old one tested OK seems they have a built in fault.

[Frankenkit]

Woohoo another CB650 owner, welcome to the land of the confused.
So you swapped yout rotor over and your charging returned to normal, me too...even tho the old one tested OK seems they have a built in fault.

What a wonderful and eloquent way to say CB650 rotors suck.

[London Dock]

Woohoo another CB650 owner, welcome to the land of the confused.
So you swapped yout rotor over and your charging returned to normal, me too...even tho the old one tested OK seems they have a built in fault.

Well Hush for me, I replaced the rotor which was out of spec (1.5 ohms...could be within the measurement error but I took no chances), however the real culprit was the stuck rear brake switch. It would only happen on a light tap of the rear brake, and then stay lit draining the battery. A simple twist of the positioning nut fixed this...BTW thanks for turning this into another 650 charging thread  !

Here are some pics of the oil leak. The first shows clearly the sheen of the oil around the bolt head:

...which dribbles down to the head fins:

This only happens after a little riding (30 mins). The lower fins are dry:

So do I torque it to spec first (haven't checked this yet) and observe the results? Figured that these are the last two bolts in the cylinder cover torque pattern and thus can easily be checked. Or remove washers, inspect/replace, RTV seal, etc? Any problems with the RTV running inside or being able to be removed?

[Frankenkit]

RTV is pretty pasty and dries to feel like rubber cement.  That said, I wouldn't go nuts putting it all over the hole, but just a thin layer under the washer, then torque to spec.  My left one (but only the left?) does that and honestly it doesn't bother me too much. There are other, way worse leaks that could happen. this one's so minimal I just don't sweat it.

[London Dock]

Thanks Kit!

[Frankenkit]

np! the only caveat to all that is that I did the same RTV sealing and I noticed after my last ride that just a tiny pinpoint of oil seeped through my RTV fix.... so it's not permanent, but the leakage is greatly reduced, anyway.

[MosquitoJones]

Mine leaks in almost that exact same area (instead of weeping from the bolt it leaks from the gasket).  I was planning on getting a new gasket, I think it was $16 for OEM at the Honda shop.  The left side of my engine is really gooey, the right stays clean.  It's never affected the running of the bike, other than the oil that burns off when the engine gets hot.  Let us know how the repair goes.