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Discussion Starter · #1 ·
Hi all,
I'll use this as a project log for something I've had planned for a while. I have a 1976 CD175 here in the UK, for about 6 years now. It has a pretty nice patina, and has been mechanically rebuilt with new all new cables, tyres, brakes, bushings, etc. I just put new rear shocks on as well. (I should have documented that, but I bought some new shocks on Ebay from Thailand and swapped the blue covers to maintain said patina). The bike is a UK model with no electric start, and the kick shaft is worn out and it is very difficult to find a good replacement. The lights are WEAK and I would like a 12V upgrade with LEDs. It would also benefit from more power. And another gear. I would just drop in a CB200 engine, but I want to keep the single carb head. SO, let's just put a CD175 head on a CB200 engine.
Below is the bike.
 

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Discussion Starter · #2 ·
I bought a rough CB200 engine on Ebay. It was just loosely assembled but had everything I need. Anything missing from the bottom end I can steal from my CD bottom end, with some exceptions. The CMSNL website is very helpful in this regard.
 

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Discussion Starter · #3 ·
One thing to note: the CB200 does not have pressure fed oiling on the points side of the cam. See the picture below, there is no oiling hole (will try to add a CD175 head picture for comparison). On the CD the oil comes up the left rear head bolt, and is fed from a hole in the crankcase the leads to the oil galley. On the CB engine there is no hole in the crankcase. I think what I'll do is modify the cam carrier to accept splash oiling as the CB one does. I will cover all this with better pictures as it goes together.
 

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Discussion Starter · #4 ·
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.
 

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Discussion Starter · #7 ·
Weird damage to the kick shaft bores and retaining pin. What happened here to shear the pin, did the kick shaft get driven into the case somehow? The kick shaft was missing so I can't say. I will have to remove the pin somehow and dress the bores. I might try to tig a rod to it and slide hammer it out. Or maybe just drill a new hole at a different angle and install another pin. It only keeps the shaft from moving axially.
 

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Discussion Starter · #8 ·
The crank bearing rotation dowels have been smashed into the case, because someone didn't line them up properly when they tightened the crankcase. I can get the out and they seem ok. One bearing does have damage to the corresponding hole, but I can use the bearing from the CD engine.
 

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Discussion Starter · #9 ·
Here is a picture of the kick shaft on the CD, it is pretty wiped out. I have a plan for this, I will get a new 14mm kick shaft from another bike, then cut and shut it together to give the old shaft new splines. I'll tig it together in a jig.
 

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Discussion Starter · #10 ·
The CB engine parts and the CD head have now all been stripped and degreased, and will be brought to the vapour blaster. 1mm oversize pistons have been ordered. I will update with more pictures this weekend.
 

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Discussion Starter · #11 ·
Parts have been removed and cleaned, as best as I can. Degreasing them is a real pain. First quote is £230 for vapour blasting. More quotes coming.
 

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For that kind of money, it seems you could buy your own blaster (if you already have sufficient air system).
 

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Discussion Starter · #13 ·
Hello pidjones!
I do already have a media blast cabinet, but just for sand/oxide. Wouldn't want to use that, it would take forever and be very hard to clean. I'm happy to pay someone this time, although I was a little surprised at the cost.
 

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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.
Wood Gas Font Auto part Metal
 

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Discussion Starter · #15 ·
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. View attachment 317421
Hello IMband, Thank you for the picture! I was considering using the CD175 cam carrier, and drilling a splash oil hole on the backside to replicate the CB200 cam carrier. Or, as you say I can drill the hole in the crankcase, to replicate the CD175. I didn't know CB200s ate up the cams, but if that's the case then I should drill the hole in the spot indicated with the red arrow. I'll measure the hole on the CD175 and drill the CB200 top case.
 

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Discussion Starter · #16 ·
Here is a question: On the CB200 the cylinder studs are all the same length, but have a different part number for the ones noted in the picture. Those studs seem to have some kind of rubber bit around them. The CD175 are all the same part number. Anyone know why this is?
 

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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.
 

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Discussion Starter · #18 ·
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.
Cheers, they are probably like the hard rubber discs that Honda puts between the engine fins. I've already removed the studs and will be using the CB175 ones like you say. I did a mock up with all the engine parts to make sure they all fit and everything looks good.
 

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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.
 
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