Author Topic: Just bought a used '72 cb750 engine. Opened the oil pan and found some gunk.  (Read 557 times)

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Offline specialone70

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Looks like some silicone and metal (some was magnetic, some was not). The engine supposedly ran and has 20,000 miles (according to the guy I bought it from) and I paid $150. How'd I do?  Do you fellas think it's serious?

Offline seanbarney41

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looks fairly typical with these.  As long as the cam gets oil, it will keep running.  I would just run it until it breaks, then buy another for $150.
If it works good, it looks good...

Offline specialone70

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I checked in the valve access ports and didn't see any soot (like I found in the engine it's replacing, which wasn't getting oil to one of the plain bearings) so I think we're good there. Thanks for the reassurance!

Offline seanbarney41

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Peek in the exhaust side tappet covers while it's running, if oil splashes out, your good to go for a while...basic tune up #$%* will totally help too
If it works good, it looks good...

Offline PeWe

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Rubber from chain tensioners. I think these engines must be opened completely and replace chains and tensioners, the rubber wheels become hard and grinds into small pieces. Primary chains and cam chain.
Check if all clutch plates are intact. The alu like flakes can be clutch fiber plates. I have seen that in my engine.
Edit: Cam sprocket bolts can touch head if too long causing alu flakes. Mine were very close so I filed them shorter
« Last Edit: November 24, 2014, 03:28:19 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline chewbacca5000

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Get a magnet and see if anything is attracted to it.  Does not look too bad to me.  Clean screen and pan well.