Sprocket Oil Seal Help

[zeech]

I've got a 1979 CB650 and apparently it has a split oil seal for the sprocket and not a normal push in one like the 550, and splitting the case is the only way to get the new one in... I'm hoping this is not the case but am afraid that's the boat I'm in. Seal is leaking pretty bad and needs to be replaced. I have a new seal.

Alternatively, can I split the case from the bottom? Or do I have to break it down from the top?

Thanks for any help.

[jcasey007]

I'm afraid you have to split the case to fit the seal as it's an interference fit between the two half cases.

Good news is you can open her up from the bottom end so you don't have to disturb the top.

Good luck

Jim

[zeech]

Great, thanks Jim. Do I need to worry about re-sealing the case or should it be okay just dropping it back together? I only need to get it open a bit in order to get the seal in.

[jcasey007]

If you are going to crack the seal I would clean and re-seal as a matter of course, that last thing you want is a leaky engine when that is what you are trying is fix

[zeech]

Okay, apparently Hondabond 4 is the best thing to use in an incredibly light film?

Also, ideally I don't want to pull the pistons out of the jugs and completely pull the halves apart. Is it possible to change the oil seal and clean the case halves without having to completely pull them apart?

Any other things I need to be aware of when splitting only the bottom end?

[davesee]

i'm gonna bump this for you zeech, because i am in the same boat. did you have any luck on this? splitting the cases is about the only thing i've never done and it scares the heck out of me.

[zeech]

I haven't done it yet. Still need to figure out the best way to go about it, not sure if the engine should be upside down or what. Ideally I just want to lift the bottom case off without disturbing anything else, put in the oil seal, reseal the case with Hondabond and be done with it.

[jcasey007]

With engine out of the frame, remove the three side covers ( clutch, ignition and alternator)
Remove the stator, clutch and gear change mechanism, remove the starter

Now remove the bolts on the top of the gearbox (4 of them?)

Now turm the engine upside down, I use 4 breeze blocks to keep it on the level

You can now go ahead and remove the sump, once off, you are now ready to remove all the lower bolts and separate the engine cases

All in, you can do this in less than an hour once the engine is out of the frame

I have assumed you have a manual as with all engine jobs the devil is in the detail!

Cheers

Jim

[MiGhost]

With engine out of the frame, remove the three side covers ( clutch, ignition and alternator)
Remove the stator, clutch and gear change mechanism, remove the starter

I have assumed you have a manual as with all engine jobs the devil is in the detail!

Cheers

Jim

The stator stays attached to the cover. It is the rotor that gets removed from the crank.

While you have the cases split. Take the time to inspect\replace the starter clutch springs, caps, and rollers.

[jcasey007]

Yep your right, but it's not nessisary to remove stator unless the crank seals are being replaced as well

[zeech]

So the rotor has to be removed or it's not mandatory?

[jcasey007]

Sorry I meant rotor and not stator,, rotor can stay on if you are not replacing the crank seals, but to be honest, if your splitting the cases I would change both crank seals as a matter of course while it's apart

[Folsoml]

Before you crack open the case, be sure that the leak is caused by the countershaft oil seal, and not the O-ring that should be on the bolt. I've received information that this is a likely cause for a leak in that same area (I'm dealing with a similar problem with my 1980 CB750C).

Part 91305-422-000

[jcasey007]

Hi folsomi

Which bolt is that? You have me thinking that I missed an O ring on my rebuild

Cheers

Jim

[Folsoml]

Hi folsomi

Which bolt is that? You have me thinking that I missed an O ring on my rebuild

Cheers

Jim

I'm terribly sorry but I think I may have offered a false hope. The CB650 setup seems to be different in that it does not use an O-ring on the sprocket bolt. This particular O-ring, 91305-422-000 O-RING (9.8X2.4), was used in many different bikes from as early as 1979 to 2012 (probably used on current bikes as well). Unfortunately it is also used in several different places. When I saw this thread, I scanned the parts fiche to see if it was used on the CB650 as well. My eyes apparently caught on "1979 CB650" but I did not pay attention to it's use on that bike: "A AIR CLEANER."


On an unrelated note: I see you are from Stratford Upon Avon. I was there a few years ago on holiday. It is a beautiful town.