Topic: K8 Engine Damage - cam shaft sprocket in pieces

[jonda500]

Glad this has a happy ending!
I was also very lucky when this happened to me in the eighties - I pulled an allnighter on my 400-4, I think just to replace the primary chain. I was so impatient to finish that I accidently left the two M7 sprocket bolts only finger tight! I started it up at the crack of dawn and went for a test ride around the block but didn't make it very far - some alarming noises started and seconds later the engine stopped dead and wouldn't turn. I pushed it home and took the cylinder cover off to find the cam chain draped over the camshaft with no sprocket anywhere to be seen! It was down the camchain tunnel in many pieces.
I had to pull the engine completely apart again to clean out all the pieces and this time put new camchain guides & tensioner, new camchain, new sprocket obviously, new rings and I made sure I tightened the retrieved sprocket bolts properly with loctite! I thankfully didn't have to do the valves - it was only idleing when it stopped dead so I think the crankshaft and camshaft stopped turning almost simultaniously.
John

[RAFster122s]

So, 12mm wide is bad? But 9mm wide is good, right? I think someone said to use clamps, the European style of solid band clamps and not perforated, that are no more than 10mm wide.

[anotherCB]

That's a good story Jonda500. I bought my bike as "ran when parked, doesn't need much" and since you can't check much with the engine in the frame on the 750 I just rode it....which resulted in a thread with 150 posts!

[PeWe]

12mm is what is on now, before 9mm.
Rubber very soft, clamp sinks in.  I think wider is better, less risk  they sink inwards. Clamp over the entire area.
Old cracked Honda rubber.

[anotherCB]

My bike won second place at the virtual Harvest Classic in Luckenbach (Texas), which is a pretty well known antique bike event around here 

[bryanj]

Well done, rebuilt complete now just the uncomfortable driving!!

[anotherCB]

I bought clip-ons with a 1-inch rise, will pad the seat some more and also install the original airbox for a tamer throttle response. It’s a fun ride as is but not for more than 30 mls!

[PeWe]

I like 250km rides on nice country roads.
Time for another build for longer rides?

[anotherCB]

PeWe for those 250 km rides (or the equivalent in mls) I still have my Stock R 75/5 and for the really long rides I take the GS. But I don‘t want to count out another stock build in the future!

[PeWe]

Always good with more than one bike!
A stock CB750 is never wrong. Or almost stock. Some old parts cost some.