Another CB77 sees daylight after 42 yrs

sixtiescycle · Post by **sixtiescycle** » Thu Jan 02, 2014 3:10 pm

I sometimes wonder why bikes are parked and forgotten. This one was used 6 years and 9K miles. I pulled the engine apart Tuesday. Pistons were new. I'm guessing there was a problem, it was pulled down, new pistons/rings installed. That didn't solve the problem and then it was parked. I found a bent exhaust valve, lapped in a new one and solved the problem. Cylinders are pitted, so a bore or replacement is in order. I went through numerous cylinders I have and came up with a std bore within specs. So many bikes I've bought had rusted cylinders on one bore so I pulled a good sleeve from one and replaced a rusty bore of another. Honed them to a nice cross hatch pattern. I have the 2 new pistons from the bike but decided to see what I have in the used dept. Came up with 2 higher compression std that are within spec's that I think I'll use with new rings. All very good used pieces that I figured there is no reason not to use. Call it a low budget topend refresh.

G-Man · Post by **G-Man** » Thu Jan 02, 2014 4:35 pm

Dick

Sounds like another success! I wonder the same thing. I have a 1960 C72 in parts that only stayed on the road for a couple of years. I haven't split the cases yet but the top end looked fine. Of course it had some broken fins on the head after being jostled around in a shed for the best part of 40 years......

If only people would lose interest before they dismantle things... :-(

G[/i]

sixtiescycle · Post by **sixtiescycle** » Fri Jan 03, 2014 4:43 am

G-Man wrote:
If only people would lose interest before they dismantle things... :-(

G[/i]

Graham,

Amen to that!!!!!

I'm going to split the cases on this one for inspection, oil seals and a good cleaning. Can't really ride this time of year anyway.

sixtiescycle · Post by **sixtiescycle** » Mon Jan 20, 2014 3:04 pm

My gut feeling told me to split the cases and I'm glad I did as the elements have taken their toll. Cases were full of sludge and the transmission has some deeply pitted gearing. The crankshaft seems okay but it's hard to tell so I'm going to replace with a known good one. I have a really nice transmission for a replacement. I was able to save a few of the existing transmission gears and while pulling it apart noticed it has offset cotters. I thought I had read somewhere that Bill Silver had mentioned none of the production bikes had these and were replaced after the bikes were sold. If so kind of blows my theory that the cases were never split on this one. It has also had a clutch replacement.

sixtiescycle · Post by **sixtiescycle** » Sat Jan 25, 2014 7:02 pm

Checkout this picture of the oil pump, In 20 years I have not had one of these engines with as much sludge as this one. I'm amazed it actually pumped oil to the head! Everything in the case will be replaced. The only good part of this engine is the head after I replaced the bent exhaust valve. I'm having to scrape the crap off the inside of the case. Nothing seems to cut through it.

sarals · Post by **sarals** » Sat Jan 25, 2014 9:45 pm

I have to wonder if the oil was EVER changed in that engine?

sixtiescycle · Post by **sixtiescycle** » Sun Jan 26, 2014 12:36 am

sarals wrote:I have to wonder if the oil was EVER changed in that engine?

It certainly makes you wonder for sure! I would have bet when I bought it that it had never been apart as it showed no tell tale signs, however I would have lost that bet as it had the new pistons, offset cotters and an AM clutch installed. Somewhere in there had to be an oil change or two. : )
Getting close to reassembly...........................

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Another CB77 sees daylight after 42 yrs

Cases split