Topic: My New '77cb550k Project - any future? (pieces of ring in the pan)

[shoemanII]

hello all,
any opinions on this bikes' potential?  just started usual checks/tear-down this morning.  here's the facts:

'77cb550k with a '78cb550k engine
nice rims, new tires, new yuasa battery, very good oem 4/4 exhaust, new clutch plates, new top-end gaskets.  all electrics work, charging system is perfect at all rpm's, compression (cold) is 135, 140, 145, 140psi.  solid tank w/rattle-can paint. 

the good:  starts easy, very strong runner, idles smoothly at 2K
the bad:  slight/moderate knock below 1800, found parts of a ring in the pan during tear-down.  pan was clean, no sludge, clean screen, had some particles that i consider normal, and 2 parts of a piston ring.

am thinking piston rings are locked in place and broken pieces can't fall into the engine/pan unless the cylinder is raised.  maybe the PO found this during the new gasket install?

my plan is to remove the cylinder and check for piston/bore damage.  am hoping the slight/moderate knocking can be traced to out-of-sync carbs or loose cam chain.  so here's my dilema,
should i shoot this puppy and get another engine, or procede.  maybe on another tack?  all ideas wlecome, many thanks!
bobp   


 

[OldSchool_IsCool]

Keep tearing 'er down.  You really won't know until you can put eye balls on the pistons and bores.  But from what I read, the bores would have to be pretty bad to put this one on the scrap heap.

Let me know if you wana get rid of those 4-4's 

[shoemanII]

found a busted second ring on #1 piston.  PO had installed new top, head and base gaskets, "o" rings, and pucks.  maybe he jammed a ring on install? - have no idea.  pistons/bores look good, recent honing.  valves, etc look fine.  other than that broken ring, am liking what i have found so far in the tear-down.  i DO like the ability of doing this top-end work with the engine still in place. 

she's a keeper, and the reworking should be fun.  thanks,
bobp

[OldSchool_IsCool]

Glad to hear it!  I picked up 4 set of STD OEM rings from ServiceHonda this winter for a little over $100.  I'm pretty sure you can order a single set if you think that's all you need.  Careful measurement of the bore will tell you if you need an STD set or an overbore.