[I M Band]

I want to use the CD cam, but because the CB crank has a different tooth count, you need to use the CB sprocket. Simo covered this in another thread. Here I confirm measurements. The cam sprocket that came with the CB engine is munched, so I ordered another one from Ebay. It is the same sprocket as in a CB350F (thanks again CMSNL). The cam that came with the CB engine was also munched, so can't use it anyway. Judging by some of the wear on this engine it has had a hard life with some poor maintenance practices and ham fisted reassembly.

If you are going to use the 175 cam, I'd suggest that you use a 175 points side cam journal. The 175 head already has an oil hole in the cylinder head, to align with the oil hole in the 175 cam journal gasket, this is not present in the CB200 head. You would need to drill the tiny hole in the top of the CB200 crankcase, which is currently left blank. As you probably already know from reading Simos log, the 175 cam is oiled from both sides, the CB200 from the tacho drive side only, then through the cam to the points side journal. Possibly why we see so many CB200 cams with a melted journal on the points side.

 

[I M Band]

It's just some kind of harmonic damper I think. Originally present on some 175 studs as well, but the rubber bit seems to go missing over time, obviously not a vital part.

BTW, the 200 studs are longer than the 175 ones, as the 200 block is some 10mm taller than the 175 part. You'll need to adjust the top engine mounting plates to suit, either elongate the mounting holes or get a CB200 top bracket.

 

[I M Band]

No, you'll need to use the CB200 studs. CB200 cylinder block is taller than the 175 block. Cylinder head and top baffle plate / cam cover are the same depth/thickness on both engines.

 

[I M Band]

Hello there,
I'm going to do this exact conversion too but not started it yet, as you seem a lot more engineering/mechanically based than I am could i ask a couple of things? Is there any mechanical reason you didnt use the twin carb set up on the original CB200 engine and as I read it from above I'm going to need a set of CB200 top mounting brackets - do you know who might do these? and finally have you married up the engine in the frame yet re the alignment of the drive and back sprockets?

These are the bits you need.

HONDA CB200 CB200T - ORIGINAL TOP ENGINE MOUNTING BRACKET AND BOLTS | eBay

Otherwise, a straight swap with a CB175 engine, into a CD175 you'd need the matching air fiters.

 

[I M Band]

How did these bikes come originally? Were only the side covers painted, and the crankcases left natural? Was everything painted? Were the cylinders and head painted?

Originally, only the two side covers and the starter motor were painted, rest of the engine left bare aluminium, not even lacquered as the fork bottoms were.

 

[I M Band]

That is impressive, Allen Millyard quality.