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Discussion Starter · #1 ·
My first ever bike was a 1980 CM200T with a 6v system and a penchant for blowing fuses. I'm good mechanically but hate electrical issues and never did sort it, just sold it and moved on to bigger. I remember the great feeling of that first ride down the highway thogh! Those were pretty low, had high bar and a cruiser feel....

Anyway though it had just speeds, no real power, and I was ready for something cool. I went from that to a 1981 Suzuki GS550 (talk about a difference!). Anyway, not the point....

Was just curious, does that bike, the CM200T have a 360 degree crank? I figure it must as it uses a single carb? From the outside the CM/CB/CBX 250 looks just like a smaller version of the 400 except the singe carb. I figured it must be a 360 crank? Is it also a 3 valve head? Ar the engines that different in size, would it take a ton of adapting to fit one larger to a small frame? No particular reason, just curious, thanks.
 

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The 200 engine is pretty much a smaller 400 though with 2 valves per cylinder. It is a 360 crankshaft though that has nothing to do with it being a single carb.

Don't know about dimensions but the differences in the frames make it look like significant mods/adapters would be required for the swap.

Western Honda Powersports- Honda Dealers 50 years In AZ Motorcycles ATVs Sales Parts Service & Repair

Western Honda Powersports- Honda Dealers 50 years In AZ Motorcycles ATVs Sales Parts Service & Repair
 

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Discussion Starter · #3 ·
It has to do with a single carb because a 180 degree twin can't get away with it because the intake strokes are tooo close.
 

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The 400 engine weighs nearly twice what the 250 weighs, mounts are wider and mount spacing is larger too. There has been some discussion on the Honda Rebel forums about this, but its generally thought that the smaller chassis may not be up to the larger engine.

Edit: but there are no documented instances where someone has tried.
 

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It has to do with a single carb because a 180 degree twin can't get away with it because the intake strokes are tooo close.
Well that is a new theory to me and I'd like to agree with you but that would make us both wrong. Lots of single carbs on multi cylinder engines .... small and large.
 

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Discussion Starter · #6 ·
Well that is a new theory to me and I'd like to agree with you but that would make us both wrong. Lots of single carbs on multi cylinder engines .... small and large.
Yes but that doesn't matter, if it's a 180 degree crank angle on an inline twin, you need two carbs. The only way one carb works is on a 360 or 270 degree crank. As long as both pistons rise and fall together, then it fires 360 degrees apart, the intake is spaced far enough apart for it to work, but it won't work correctly with a 180 dgeree crank angle which most Honda twins are.

A Harley is a whole different animal with a large carb and the intakes pretty much happen together like a thumper
 

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Yes but that doesn't matter, if it's a 180 degree crank angle on an inline twin, you need two carbs. The only way one carb works is on a 360 or 270 degree crank. As long as both pistons rise and fall together, then it fires 360 degrees apart, the intake is spaced far enough apart for it to work, but it won't work correctly with a 180 dgeree crank angle which most Honda twins are.

A Harley is a whole different animal with a large carb and the intakes pretty much happen together like a thumper
Sorry, still a no from me on your theory. I've replaced single carbs with twin carbs and twin carbs with singles on Honda, Triumph, Norton Twins of various sizes. I've replaced quad carbs with a single on a GL1100. Never, not once did the crank phasing become an issue.
 
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