Topic: broken cam chain and shredded chain guide

[73hutch]

so the struggle continues. i found another complete 550 a few months ago, to replace to botched engine rebuild from last winter. the new one rode great until last week when it died. i was pretty sure the cam chain broke. when i took the valve cover off i pulled the broken chain out. when i pulled the head off i found that the chain guide was shredded to pieces. the guide was so thin, i feel that breakage was inevitable. also there are a few bent valves, is that a result of the chain breaking? has anyone seen this before? i know how you guys like carnage photos so here are a few. so now I'm looking for another new engine...

[tbpmusic]

also there are a few bent valves, is that a result of the chain breaking? has anyone seen this before?

Yes, it probably cause the bent valves. And I have seen it before, but it's not common for cam chains to break. They're pretty durable, for the most part.
Don't write off the engine just yet, a few new valves and a valve job might do the trick. A "new" engine will just buy into a mess of other problems - there's a reason those "spare" engines aren't in a running bike somewhere.

bill2

[73hutch]

so if i were to fix this engine, i would have to put a new cam chain on (as well as fix the valves). i have to crack the lower case in order to do this right?

[tbpmusic]

i found that the chain guide was shredded to pieces.
.....
 i have to crack the lower case in order to do this right?

[/i]

Sadly, yes you do have to split the cases.

You want to do it anyway, to find all those pieces.

bill2

[73hutch]

i know there's going to be some pieces there for sure. i think my plan is to find an engine i can throw in there and ride for the rest of the season, while i work on this rebuild...

[scartail]

i know there's going to be some pieces there for sure. i think my plan is to find an engine i can throw in there and ride for the rest of the season, while i work on this rebuild...

Just for my education, would there be some way to flush out the pieces or pick them out with a magnet?? So, the case wouldnt' have to be split?

[tbpmusic]

Just for my education, would there be some way to flush out the pieces or pick them out with a magnet?? So, the case wouldnt' have to be split?

Not on my bike, thanks - there's rubber and aluminum, not magnetic in the first place.

Plus, there are just too many inaccesible nooks and crannies for that crap to hide. Then they break loose and plug an oil passage somewhere.

bill

[deerslayer]

Well, get out the calculator and figure out what all the repair parts would cost and then compare that to what an engine would go for. If the numbers are similar I think I would go for the repair. At least then you know what you have. If on the other hand you can find a complete running engine for a good price, that would be faster. You could then repair your broken one at your lesiure. (for me, it would never get repaired unless I had an immediate need for it. Just not that motivated...)

Did this engine have a lot of miles on it or was it perhaps not maintained properly? If there are wear or neglect issues they may affect other parts of the engine/transmission as well and may be a factor in which direction you go. Since the case has to be split to repair it anyway, why not take a look and see what you have in there? May tip the balance one way or the other.

Hope you get rolling again soon one way or the other.

[Raul CB750K1]

Don't tell me you bought the chain at Sirius Con Inc. I did and I'm through what you are going..... 

[hatchett]

I'm rebuilding one right now with the exact same issues, aside from the bent valves.  A bit of a headache, but will be worth it soon enough.  You must seperate the cases to install an endless chain anyway, so make sure you get all the broken pieces out.  That chain guide is easily found on ebay for cheap, btw. 

[HondaMan]

so the struggle continues. i found another complete 550 a few months ago, to replace to botched engine rebuild from last winter. the new one rode great until last week when it died. i was pretty sure the cam chain broke. when i took the valve cover off i pulled the broken chain out. when i pulled the head off i found that the chain guide was shredded to pieces. the guide was so thin, i feel that breakage was inevitable. also there are a few bent valves, is that a result of the chain breaking? has anyone seen this before? i know how you guys like carnage photos so here are a few. so now I'm looking for another new engine...

73: was this an endless chain that broke? (Even more rare). I've seen the ones with master links come apart, but not the endless ones. (Harder to install, though...)