SOHC.co.uk Forums > CB750

Cracked crank cases.

(1/3) > >>

royhall:
Hi all.

I am rebuilding a CB750K4 engine for Alan (MCTID).

Got the engine apart and am cleaning up the parts. After removing the thick goo from around the drive sprocket area (looks like the goo was deliberately spread out to cover it)I have discovered deep score marks and a large crack in the lower case, caused by a chain breakage.

The crack is beyond welding up as the alloy has been pushed inwards and is twisted.

Does anybody have a spare set of cases (obviously I will need both halves as they are a matched set) they would be willing to sell.

The bike is a CB750K4 USA import. I think (not certain) that K3 to K5 cases are all the same.

Thanks. Roy.

Bryanj:
Roy a decent alloy welder should be able to tap back the broken bit and weld up the damage, may be easier than newish cases

royhall:
Cheers Bryan. Am I right in saying the K3 to K5 cases are the same, and possibly K2 as well.

A few pictures of the damage.

[ Guests cannot view attachments ]

[ Guests cannot view attachments ]

philward:
Hi Roy
I've got a set - I go in the shed and get you an engine number - I'm in Wigan
Phil

philward:
Hi again Roy
Engine number is CB750E - 2727871. They need a good clean up as have surface corrosion. If not suitable, I have a complete engine from a K5 (from memory) that is weather seized - I don't know internal condition. Don't want a lot for either
Phil

Navigation

[0] Message Index

[#] Next page