Topic: was running grear/towed home part 2 (found problem)

[carl550k]

found out what caused the 550 to quit.i pulled the tappet covers off and spun over the motor only to see no movement from the valves.i pulled the valve cover off to find a broken timing chain.i got the chain out , it looks like a broken link.what are my options now? is it possible to fix without tearing the motor completely apart?it is about 2 months away from snow season, i would hate to put the bike away now. there is a local cycle junk yard with a 550k motor for reasonable, that would be the fast out.could i upgrade to a bigger motor? maybe a 650? but what would work in my 76 550k frame? any suggestions? this site has proven invaluable.some of you out there gave some of the best advise. thanx. bummed out, carl

[TwoTired]

Go for the engine swap.  You probably have some bent valves, too.

You can have the engine swapped in a a day or two.

[heffay]

get the engine from the yard... pull the old one apart... make a better new one

then... you'll learn somethin in the process while not "expecting the yard motor to be better than the newly caked one"
                    (two tired: did you forget to mention that or what?) 

[fergie]

apparently the 650 motor fits(11 more hp,electronic ignition:)

[TwoTired]

Heffay,
I assumed he wanted to get back on the road as fast as possible before the snow forced hibernation.  While the old motor can be fixed, most likely, checking and replacing the valves and guides, searching for metal in the sump, and fishing another cam chain into what he has now, is going to take someone inexperienced a good bit of time and a couple hundred dollars in parts.  I'd certainly check over the yard engine carefully and at least do a compression check before the changeover.  But, if the yard offers some garantee that it's a good engine, changing it out is the fastest way to get going.  Then, if he wants to fix the toasted one, he can do that over winter, where he can take his time, and get winter pricing on parts off ebay.  
I've never seen a Cb550 with a broken cam chain.  Danged things are strong.  Probably something wrong with the tensioner, I expect.
Cheers,

[Lumbee]

if the yard offers some garantee that it's a good engine,

   ...that was a good one twowired...

[heffay]

last yard i went to the old guy was giving the grandkids rides on the st bernard cuz that was the only thing in the whole yard that ran!!!