caveman592
Been Around the Block
hey would it be ridiculous to put 22mm carbs on a Cb200? I mean would they fit without redoing the intakes? I know the center beam would cause a problem but otherwise could it be done?
Carbs on a cb200
- Thread starter caveman592
- Start date
We have run 18mm stock carbs on a 200cc CB160 race bike and 26mm carbs on another CB175 based racer, so YES it can be done. Not all "22mm" carbs are the same size though. Some of those on ebay are tiny.
You will probably need new carb manifolds/insulators ie the rubber things the carbs pop into.
You will probably need new carb manifolds/insulators ie the rubber things the carbs pop into.
caveman592
Been Around the Block
Any guess on how to make new intakes or maybe a place to buy? I guess I would need to pick out the new carbs first. From what I have seen vms' are well liked. Do you have any suggestions on what to look at?
For a stock or close to stock motor, I'd stay stock. The stock carbs are cheap if you already have them and very odd at the outlet IIRC. Couple of guys have worked through those issues, but for my money, I'd port the stock carbs and leave it at that.
That 200cc CB160 with stock carbs could stay with our CL175 sloper motor with 26mm carbs until the very top end where it lost out a little but it was faster accelerating out of corners. I'm building another CB160 race bike and it will have stock carbs.
That 200cc CB160 with stock carbs could stay with our CL175 sloper motor with 26mm carbs until the very top end where it lost out a little but it was faster accelerating out of corners. I'm building another CB160 race bike and it will have stock carbs.
caveman592
Been Around the Block
Interesting information here. So what kind of engine modifications would warrant replacing the stock carbs? Would a simple custom exhaust be enough or would you need bigger pistons a hotter cam things like that to make the change worth it. I see you run stock carbs on your race bikes do they all have major engine modifications done? I guess what I am getting at here is that I want to improve on the "economic" and "gas saving" design of the cb200. From what I have read it would be able to keep pace with a cb160 if the cb200 was bone stock. My goal would be at least to have it reach the level of being on par with the cb160s but I would love to take it further while of course keeping it tame enough for the street as there are no tracks here in Bend, Oregon.
I just deleted my reply, so let's try again.
Carb size is a function of engine capacity, revs and length of time it's open. Longer cam timing means more time to fill the cylinder through a small carb. Bigger bores mean more air and that tends to become a problem. Up to 9500 or so stock carbs are fine but they limit revs above that. Gas can only travel so fast in a port at around 0.55 mach a pressure wave is created that effectively chokes the intakes at the critical port diameter (around the guides).
CVB160 was revver and could use those larger carbs. By the time the CB200 was introduced, they were typically being ridden less hard and smaller carbs were fine - even with larger motor sucking through them.
In a well developed 200cc CB200/160/175 motor, carb size would be around 24mm - 26mm, to work with a slightly cleaned up intake port, - don't try to port it, it flows enough already. That would pull well up to 12,000 which the engine can't get to anyway with those heavy pistons.
A better cam means the valve is open for longer which works with the same small carbs because the gas has longer to get through the hole, so it doesn't have to travel as fast.
As a sort of ball park, small carbs make for better low speed pickup and better economy because they mix air and fuel better with their higher gas velocities. At higher revs that stock carb is too small and chokes the motor off at 9500 or so.
If it were my bike, I'd clean up the ports and valves, fit new springs and a mild cam (Megacycle) and I'd raise the compression to make it work harder at all revs and I'd fit an electronic ignition. If i was planning to race or rev it hard all the time, I'd fit larger carbs. If I wanted to tool around on the street at less than say 9500 revs most of the time, I'd clean up stock carbs.
It all comes down to how you plan on riding it and the depth of your budget. with an open ended budget, and hard rider revving the nuts off it all the time - go with 22 or even 24mm carbs. Budget less expansive, and riding habits more restrained, start with stock carbs and see how that works for you.
At 200ccc it will never be a fire breathing monster. The trick is to get the most out of it for the way you ride. Raising compression really helps at all revs, big carbs help at high revs and hurt low speed. If you start off with stock carbs, clean up that lump in the middle of the bore to get them to flow a little better.
You will find that set up will be more important than carb size. Well set up stock motor will make more power and be faster than a badly set up full race motor.
As you can tell, I'm avoiding telling you what to do, by trying to help you make a decision that's right for you based on you understanding the options.
Carb size is a function of engine capacity, revs and length of time it's open. Longer cam timing means more time to fill the cylinder through a small carb. Bigger bores mean more air and that tends to become a problem. Up to 9500 or so stock carbs are fine but they limit revs above that. Gas can only travel so fast in a port at around 0.55 mach a pressure wave is created that effectively chokes the intakes at the critical port diameter (around the guides).
CVB160 was revver and could use those larger carbs. By the time the CB200 was introduced, they were typically being ridden less hard and smaller carbs were fine - even with larger motor sucking through them.
In a well developed 200cc CB200/160/175 motor, carb size would be around 24mm - 26mm, to work with a slightly cleaned up intake port, - don't try to port it, it flows enough already. That would pull well up to 12,000 which the engine can't get to anyway with those heavy pistons.
A better cam means the valve is open for longer which works with the same small carbs because the gas has longer to get through the hole, so it doesn't have to travel as fast.
As a sort of ball park, small carbs make for better low speed pickup and better economy because they mix air and fuel better with their higher gas velocities. At higher revs that stock carb is too small and chokes the motor off at 9500 or so.
If it were my bike, I'd clean up the ports and valves, fit new springs and a mild cam (Megacycle) and I'd raise the compression to make it work harder at all revs and I'd fit an electronic ignition. If i was planning to race or rev it hard all the time, I'd fit larger carbs. If I wanted to tool around on the street at less than say 9500 revs most of the time, I'd clean up stock carbs.
It all comes down to how you plan on riding it and the depth of your budget. with an open ended budget, and hard rider revving the nuts off it all the time - go with 22 or even 24mm carbs. Budget less expansive, and riding habits more restrained, start with stock carbs and see how that works for you.
At 200ccc it will never be a fire breathing monster. The trick is to get the most out of it for the way you ride. Raising compression really helps at all revs, big carbs help at high revs and hurt low speed. If you start off with stock carbs, clean up that lump in the middle of the bore to get them to flow a little better.
You will find that set up will be more important than carb size. Well set up stock motor will make more power and be faster than a badly set up full race motor.
As you can tell, I'm avoiding telling you what to do, by trying to help you make a decision that's right for you based on you understanding the options.
caveman592
Been Around the Block
Thanks for the help that info was exactly what I was looking for. Your wealth of experience is truly appreciated.
Texasstar
Can't is a four letter dirty word
Teazer we are boring our cb200 .75 over adding racing springs new stock valves snd new cam chain from Les. Can we use mega cycles mild cam with no other modifications? We are adding 175 exhaust without the muffler. I read a cb 200 review that posed the question what would the cb200 be like with the 175 cam and exhaust and the 160's carbs. How much can you take off of the head and still have enough valve clearance to raise compression from stock?teazer said:
That question is rather like the old "how long is a piece of string". And the answer is that it all depends.
With a stock head and barrels and stock cam - probably close to 1mm before it becomes a real issue. Valves can be pulled back (recessed) into the head, valve pockets can be deepened and so it goes on. I like to machine the piston crowns at a certain angle on the squish band and then machine the barrels to bring the pistons up to where I want them. Then I machine a little more off the head and cut match squish bands.
I usually start conservative and then pull it down to shave some more off. 200 head has a wide useless squish band that needs help. You want to end up with 0.8mm-0.85mm squish depth and 1 degree difference in squish band angles. That's what I do and if you fiund a better combo I'd like to hear about it.
With a stock head and barrels and stock cam - probably close to 1mm before it becomes a real issue. Valves can be pulled back (recessed) into the head, valve pockets can be deepened and so it goes on. I like to machine the piston crowns at a certain angle on the squish band and then machine the barrels to bring the pistons up to where I want them. Then I machine a little more off the head and cut match squish bands.
I usually start conservative and then pull it down to shave some more off. 200 head has a wide useless squish band that needs help. You want to end up with 0.8mm-0.85mm squish depth and 1 degree difference in squish band angles. That's what I do and if you fiund a better combo I'd like to hear about it.
eyhonda
Coast to Coast
Can you use a copper head gasket instead of milling the head? Can you also mill the bottom of the cylinder instead of the bottom of the head? No problem for the cam tensioner to take up the 1mm slack? Sorry, if any of these are dopey questions. I'm just pondering out loud. I've never tried raising compression thru means other than by a domed piston. Will another Honda piston fit (350 or 400 four)? I could research that last question but I figure I could throw it out there as being in the same category.
