Massive oil leak, CB72

CharlesM · Post by **CharlesM** » Sat May 23, 2015 4:54 pm

Just picked up a CB72 racer. No idea what it's like on the inside but some good stuff on the outside. Starts and runs well, except for the huge oil leak from the oil seal about the clutch push rod on the right hand side of the engine. The seal looks new, but oil leaks from round it. when I pull the rod out oil streams out from the hole where it would have been, ie the oil level is above the pushrod hole.

Just a new seal or possibly overfilled with oil too?

Based in the UK. Thank you.

LOUD MOUSE · Post by **LOUD MOUSE** » Sat May 23, 2015 5:16 pm

Welcome to the forum.
Please add your location and other information to where you signed up to the forum.
I'd say that the oil actually starts on the clutch side and I suspect the "O" ring at the shaft where the CLUTCH LIFTER JOINT installs into the TRANS MAIN SHAFT is either warn or not there.
If tou don't have a parts book I recommend you get one for sure.
Can you offer pics of the bike?. ...................lm

CharlesM wrote:Just picked up a CB72 racer. No idea what it's like on the inside but some good stuff on the outside. Starts and runs well, except for the huge oil leak from the oil seal about the clutch push rod on the right hand side of the engine. The seal looks new, but oil leaks from round it. when I pull the rod out oil streams out from the hole where it would have been, ie the oil level is above the pushrod hole.

Just a new seal or possibly overfilled with oil too?

Based in the UK. Thank you.

CharlesM · Post by **CharlesM** » Sat May 23, 2015 5:24 pm

Ah. That makes sense. Didn't think of that. I'll have a look and let you know.

Some pictures posted. Fairing on (just, not quite right but it's the one it came with). Next it stop the leak and then look at megacycle cam/nova 5 speed box and a bit of head work.

G-Man · Post by **G-Man** » Sun May 24, 2015 2:34 am

Charles

Nice looking project. I have a PDF manual I can email you if you PM me your email address.

G

CharlesM wrote:Ah. That makes sense. Didn't think of that. I'll have a look and let you know.

Some pictures posted. Fairing on (just, not quite right but it's the one it came with). Next it stop the leak and then look at megacycle cam/nova 5 speed box and a bit of head work.

sarals · Post by **sarals** » Sun May 24, 2015 12:17 pm

Wow! That looks REALLY nice!!!

OldScrambler · Post by **OldScrambler** » Sun May 24, 2015 1:13 pm

Nice Indeed.....................Looks like well sorted suspension.

CharlesM · Post by **CharlesM** » Wed May 27, 2015 3:55 pm

So had it more apart and we have massive amounts of brass deposits in the sludge trap. Everything looked to be ok and it sounded fine when it was running.

Where are the brass bushes?

Regarding the original leak the small o-ring inside the mainshaft was slightly damaged and worn and the oil guide pin (pic attached) was broken. I'll replace the o-ring and the clutch push rod oil seal (think its called o-ring 8216) anyway. But what is the purpose of that pin? I'll get myself a manual soon. I expect the engine is coming out, although it clearly had been recently split and the cam chain is certainly new.

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Massive oil leak, CB72

Massive oil leak, CB72

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