Topic: CB550 Engine/trans problems

[76_Paul]

Last week, I bought a 1976 CB550k with a seized engine.  I was hoping that it would just be bad rings, but I think it has turned out to be much worse.

The rear wheel will spin freely in neutral, the rear wheel will not spin when the trans is in first gear.  The trans will not shift into any gear other than neutral and 1st.

I started by removing the spark plugs and pouring Marvel into the cylinders, after about a week of gently trying to "shock" the pistons loose I decided to start digging in to the engine.  Upon removal of the cylinder head I noticed one of the cylinders was full of crap AND half of the related exhaust valve.

Even with the cylinder head off I can still not spin the rear wheel while the trans is in first gear (still spins in neutral).

My question: How much more should I dig in to this engine?  Would it be cheaper at this point to pick up a used engine, freshen it up, and slap it in?  I included some pics, please feel free to mock the "mural" on the fuel tank.  Yes it is a picture of waves crashing against a rock in the moonlight.  And yes, the tank will be re-painted before the moto sees the road again.

Note: I have read the FAQ and while there is a ton of helpful info, I did not find anything that addressed my situation.  I also performed a Search and netted to comparable questions.  If it is out there and I missed it, please point me in the right direction.

Thank you

[OldSchool_IsCool]

Welcome to the forum, Paul!

Are you saying you found a broken exhaust valve in one of the cylinders?

I would take the clutch basket out (under right rear engine cover, oil inside) and see if the rear wheel turns in 1st.  If it does, the engine is seized.  If it does not, then the seizure is in the transmission.  If you can get the rear wheel to turn in 1st, see if you can now get into the other gears.

[1timduke]

+1 on the clutch removal, when the oil comes out, note it's condition.   If you got a lot of shavings or hunks of trash in there, you could be looking at some more work.

-Tim

[76_Paul]

Thanks for the help.  The bolts holding the cover looked pretty rough so I soaked them with WD40.  I'll check them again and see if I can access the clutch basket...

I'll let you know what I find out.

[Hush]

When the bike is in neutral only the front sprocket is being turned so that only tells you the chain and front/rear sprockets work.
Sounds like deep deep trouble in there somewhere, I use the old piece of soft wood and a hammer to gently tap and move siezed pistons downwards, give them a good soak in something thin enough to penetrate.
Keep the forum up to date on your progress, don't be afraid to ask the dumb questions, once we stop laughing we can be quite usefull.

[76_Paul]

Ok.  Here comes dumb question #1.

How do I remove the kick start pedal?  I have removed the pinch bolt and even removed the entire pedal.  But the pedal housing the extends into the clutch cover will not come out.

I have removed all of the bolts holding the clutch cover but it will only seperate from the case about 1/4" as the kick start seems to be holding it up.

Any tips?

EDIT: Picture attached

[bryanj]

Ah you should not have split the pedal from the boss, if you look closely you will see a "join" that the pinch bolt closes up as a clamp, get a big flat screwdiver in there and open it up then the boss shouls slide off the splines

[OldSchool_IsCool]

+1 what Brian said.  Everything circled in box #4 should still all be together.  Bolt #19 should come all the way out then the entire assembly will slide off the spline with maybe a little help from a screwdriver.  Petal 13 may need to come off to.  Again, take it's pinch bolt all the way out.

[76_Paul]

Thanks.  That did the trick.

The clutch cover is now off.  I was able to also remove the pressure plate, but I lent my snap ring pliers to a buddy so I will have to wait to remove the 25mm snap ring that is holding the clutch assembly to the main shaft.

BTW I just found a 1975 cb550 frame and engine for $200.  The best part is that the frame is titled (my 1976 is not) so that will save me some hassle and $$$ at DMV.  I plan to pick that up tomorrow.  It's not complete (no carbs and who know what else) but at least I will be that much closer to getting a streetable bike.

Thanks again for all the help on this!!!  I know I will have more questions as a build my cafe.

[76_Paul]

Quick update...I figured out why the engine wouldn't turn over. 

I was pulling the stator cover off to install on the "new" bike I bought this morning and as soon as I removed the stator (which involved a fair amount of prying) I noticed all the pistons jump.  It appears that the stator coil or field coil was solidly rusted on to the rotor and that was contributing to the seized engine diagnosis (although the #1 piston was attached to its cylinder as well). 

I hate it when multiple failures contribute to a problem.   

But don't get too excited, the trans will still only shift between first and neutral.

[bryanj]

Thats common unless you spin both shafts at once