Topic: CB550 Crankcase vs. Chain

[Paul E.]

Trying to chase down some minor oil leaks this weekend, I opened up the crankcase to look around.  Judging by all the built up grease and junk inside, it hasn't been cleaned in awhile.  Intermixed with the grime, were some metal flakes, so I popped off the sprocket, and it looks like something has been rubbing against the rubber coated plug.  It's worn away the rubber and has started to eat into the aluminum.

The chain that's on the bike, is what the previous owner had installed.  I don't believe it is an O ring type chain, so I wouldn't think it would cause clearance issues.  But something had to have worn away the rubber, either the current chain and sprocket or perhaps a previous setup that was run.  The metal flake has me thinking that it is currently being worn away.

So, what can I do to figure out if the chain is still rubbing against the crankcase, and how can I fix it?  A few pictures to show what's going on.



pretty gnarly oil pressure switch corrosion going on too




here's the current chain on the rear sprocket, looks like a normal chain to me?

[Stev-o]

Something's wrong, my 550 is approx 20mm wide overall, yours?

I'd change the sprockets and chain and make sure it's not rubbing before damage is caused.

Nice cleanup, by the way!

[goldarrow]

Yeah on the new chain and sprockets, ride and ride then check again for oil leak

[Tews19]

two pervious posters are correct. Change the sprocket and chain than go from there.

[Powderman]

That's not "opening the crankcase". At least the oil/grease build up shows you're getting lube to the chain, better than it being super dry in there.

[Frostyboy]

I'm a bit sus of that front sprocket being held in place by that C-clip. An OE sprocket has two bolt holes & is secured by the plate #14.
Perhaps that sprocket is able to 'float around' too much?

http://www.davidsilverspares.com/parts/by-part-number/partnumber_14592/

[Stev-o]

two pervious posters are correct.

Who you calling a perv, Tews?!

[jonda500]

I'm a bit sus of that front sprocket being held in place by that C-clip. An OE sprocket has two bolt holes & is secured by the plate #14.
Perhaps that sprocket is able to 'float around' too much?

http://www.davidsilverspares.com/parts/by-part-number/partnumber_14592/

+1  that c-clip will stop it coming off but doesn't stop it from moving inwards too far!

[Paul E.]

It is indeed an issue with the C clip failing to hold the front sprocket in place!

I put the chain and sprocket back on, and could walk the assembly inwards, to the point that the chain would rub against the crankcase.  What was the point of this sprocket?  Seeing as the stock one is usually bolted on, and this one had all that room to float...  i'm scratching my head as to why this thing was ever on the bike. 

Looks like i'll be shopping for a new chain and some sprockets this evening.  The standard setup for a '74 CB550 looks to be 17/37 and a 100 link, 530 width chain, sound about right?  Any sprocket manufacturer recommendations?  May pick up a 16T sprocket just to test it out.   

Thanks for all the great insight guys.

[Stev-o]

JT makes a decent sprocket at a very affordable price.

http://www.ebay.com/itm/Jt-Sprockets-Jtf288-17-17T-Steel-Front-Sprocket-/171904540919?fits=Model%3ACB550&hash=item28064f20f7&vxp=mtr

[Frostyboy]

Pleased to hear it all worked out. btw, I think I may have misled you with that part# for the plate. It should have been http://www.davidsilverspares.com/parts/by-part-number/partnumber_14585/

As far as reducing the size of the front sprocket goes, I think these things rev fast enough already. If you don't get out on the highway very often I suppose it could be okay, but not for me. I'm back to standard again now, but I used to run 17/34 (like a 500). It dropped revs by about 500 in 5th from memory.

[Duanob]

I got my entire drive set up here:

http://www.powersportparts.net/SearchResults.asp?Search=jt+sprocket

I went with a 36 Tooth in the rear. I wasn't searching for that ghost 6th gear all the time. But a 16T in the front will be a much bigger % change and you will be running some high RPMs on the hiway. Something to think about. Or just get the stock ratio to start, the sprockets aren't that expensive that you won't want to experiment later on.

[Tews19]

two pervious posters are correct.

Who you calling a perv, Tews?!

LOL my bad

[Paul E.]

Duanob, I think I may try 36 on the back. I'm often on the highway and find myself looking for that mystery sixth gear. How have you liked it so far?

[Duanob]

Duanob, I think I may try 36 on the back. I'm often on the highway and find myself looking for that mystery sixth gear. How have you liked it so far?

I like it! I wonder why Honda didn't put a 36T because the RPMs are a touch lower at hiway speeds but I don't notice any loss of pep taking off from stop light to stop light.

[fortworthx]

I find myself battling a similar issue on my '78 550K.  It seems the previous owner put on the new chain with a clip retainer master link that, of course, let loose and resulted in a rather disconcerting chain break at 55 mph.  It looks as though I was lucky and didn't suffer too much damage.  I was going to go with a x-ring chain as a replacement but then came across all of the discussions here warning that off so it's back to the a standard chain (for the curious, there's about a .015" difference in width between the two).  Still have a few questions, though.

Does anyone know what the tolerance is between the Sprocket Fixing Plate (#14 in the parts catalog) and the groove of the output shaft?  I discovered quite a bit of axial play on mine so I went ahead and ordered a new plate but I'm still not sure if I can trust the shaft groove. 

Is anyone aware if there is enough room for an 18T front sprocket?  I believe the diameter is nearly 0.2" larger for the 18T but it's hard to tell if there's room without actually mounting it up.  I would definitely like to have a taller gear ratio to keep rpms down a bit at highway speed.  I know it would probably be better to go to a 34T on the back but both sprockets only had a couple of hundred miles on them and the back suffered no damage.  Probably more important, I'll choose the route of less work, if it's possible.

How easy is it to replace the output shaft oil seal and the shifter shaft oil seal from the outside?  I noticed a little seepage from both and it would make sense to replace those, if possible.

[Duanob]

17T is stock for front sprocket. I wouldn't go bigger, there isn't much room left as it is.