Honda CD175 Rebuild Part 2 - Engines

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I decided to break with the tradition of restoring the bike first, then the engine, as when the two and a half engines were examined carefully it was discovered that all three were seized up solid.


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No chance of moving anything despite liberal quantities of penetrating oil, so that was it, engines first this time.


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So I started by trying to remove the cylinder head. First problem, you cant remove the head till the cam chain is removed via its spring link. Can't get to that because the engine is seized up and won't rotate. Solution? Cut the cam chain, head can now be removed.


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Now to remove the cylinder barrel, not easy. After much fine tuning with a lump hammer and drift they eventually started to move. Once out the rest of this engine restoration went fairly smoothly. A new set of plus .50 mm pistons and a re-bore with new gaskets seals etc and the completed engine looks like new.


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The second engine was not quite so straight forward. It was in an awful state, having been outside in a trailer under a sheet for a number of years and as expected seized up solid.


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First job was to remove the side engine panels in order to remove a very difficult centrifugal oil filter that was blocked solid.


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As with the first engine the cam chain had to be cut in order to remove the cylinder head.


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It could be seen that the pistons were well and truly seized into the barrel , no amount of persuasion would move either piston.


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The piston had to be chiselled and cut out of the barrel. Unfortunately the barrel was damaged in this operation but repairable.


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I don't think that the pistons are repairable ! A re-bore and new pistons called for here.


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Engine and gearbox internals, there does not seem to be any internal damage. Even the engine and gearbox bearings seem to be in good condition.


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All engine covers and crankcases have been cleaned in a vapour/ aqua blasting process ready for reassembly.


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External engine covers lacquered as original.


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Assembly nearly complete. Just waiting for the repaired and re-bored cylinder barrel. While waiting for that managed to obtain a good undamaged barrel so I had it bored to +.50mm and fitted it.


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Assembly of the second engine now complete


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Two of the three engines now rebuilt. Both have been re-bored with new +.50 mm pistons, one of these engines will be for sale once the restorations of two bikes are complete. Now to get on with the red Honda painting repair and rebuild, watch this space !