Topic: left side crank seal on 1975 cb550

[purf_man]

ok I got my CB550 back from teh shop after a long ordeal.  I just got this bike and haven't really put any miles on it (bought it from a riend who needed money...I needed a bike)  here is my problem.....I and leaking oul from the stator cover.


I have replaced the oring on the crankcase plug with a new one but I am still getting oil in the case.  now when I put the AL plug in the lower case the stator cover holds in it place right?  with the plug bottomed out in the case it is sitting about 1/8" past the case surface so that when I fire up the bike it will pop out an 1/8" where it hits the stator cover.  should there be a spacer in there?

or is that normal and I have a bad crank seal?  IF it is the left side crank seal can it be replaced by removing the stator rotor and pulling it out and driving in a new one?  or do the cases HAVE to be split?

[purf_man]

anyone?  I did a search but I haven't found a positive answer on replacing the seal with motor in frame or not.

[bryanj]

You need to split the cases to change the crank seal and its normal for the plug to move in and out. You can bolt a plate accross the plug to hold it in temporarily and run the engine with the alternator off to check for a leak

[purf_man]

does the crank need to be removed to replace the seal? or am I looking at a full teardown to replace this one seal?

[bryanj]

You can just lift the crank a little and change both crank seals. To be honest if i was that far in i would change the cam and primary chains as they do wear.

[purf_man]

do you think I could pull them out with a slide hammer (like for body work that uses a sheetmetal screw) and drive in the new seal without splitting?  reason being is I already have two bikes apart I am working on (RD400 and MT250) so not wanting a third one in a million pieces.....plus I would like to get riding it as soon as possible

[bryanj]

No you cant get the seals out as there is a "Lip" on the inside that goes into a case groove. As its the generator side just make sure the gasket is good and let it weep into the case until you have time to sort it properly, the oil wont hurt the generator

[purf_man]

yeah that works fine around town but once I hit highway speeds it is pissing out a quart in like 10 miles (IE I can't leave town on it)  so it looks like I have to break it down which sucks.  since I prob could use some new mains and rings how much am I loking at to refresh the motor myself (I can manage the teardown and build just will have the head and cylinders freshend somewhere else if it needs poked out an overbore and such)  I saw that the head gasket is preicey and the cost of new chains doesn't seem like it will be cheap either.  so about $500 to fresh it or am I looking at more?

[bryanj]

I can only quote you UK prices.
Camchain £15
Primary chain £50
Mains £5 PER HALF SHELL
Ends £5 per half shell
Gasket kit £35
Oil seal Kit £12
Rings is the difficult one as stds are EXPENSIVE at about £25 PER PISTON

Remember that you cant grind the cranks so your cheapest bet is an EBY used engine

[purf_man]

well as long as they aren't complete toast could I get by with just polishing the mains (I have no idea how bad the bottom end is in the bike)  the thing that scares me about an ebay motor is getting one with a bad crank seal, trans, etc.

[Bodi]

The #1 main bearing gets pressure fed oil, but I would be surprised if it could send out a quart in 10 miles past the shaft seal. I think it would be worthwhile to see for sure where the oil is coming from. As mentioned, you can make up a plate from metal or even plywood to bolt on and hold the plug in. It's maybe 3/4 inch in area, so with 60psi oil it will push out with 45 pounds of force or so.
If you pull the rotor you will be able to see the state of the seal. There would need to be some serious damage to leak that much. I would avoid trying to start the engine without the rotor/flywheel though. Maybe someone else has tried and knows if that is OK?
Assuming the rest of the motor is working OK you could just get a seal kit and change that seal or all the seals on the case break. Although it takes a bit of time and effort to pull the motor and take all the various parts off to separate the cases, you can slack off the cam chain tensioner and lift the crank enough to change the seal without even removing the rocker cover.

[purf_man]

well I grabbed a set of axles off my RD400 project bike and will pull the rotor this weekend I guess.  right now I am busy getting my GS550 back in running shape (or trying to at least)  if my crank seal is hosed I might take it up with the shop that worked on it last.  they seem to have a habbit of taking a long time and over charging so people forfiet bikes.  I would not put it past them to have jabbed it to make me forfiet it so they could use it for parts.  I was not aware of this practice until after I got my bike back from them.  it wasn't leaking oil at all until just before I took it in when I fired up the bike with the stator cover off and popped the galley plug out (shut down bike right away as it was pumping oil like mad out the side)

[purf_man]

Well after all these months (moved 1000 miles, took a new job working 60 hours a week, and riding my 250 ninja....)

I appear to have fixed the leak!!!


now all I need to do is clean up the motor and get it back in the bike.  I am going to respray the motor while it is out of the frame and was wondering if anyone knows of a good way to degrease the cylinders adn head?  my motor has 30 years of crude built up on it and need a way to get it off.  I was going to just rely on a light spray of solvent on it every day or two for a couple weeks then just coin wash it on a warm day.  any other suggestions?

[bryanj]

That and/or a steam pressure cleaner.
What cured the leak?

[purf_man]

split the cases and replaced both main seals.

the old ones were dried out and hard from sitting.  no tears but they were not very pliable