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Yes with the dremel ( racers do it Teazer wrote about opening up superhawk carbs in Patricks thread ) and obviously also no dont, unless youve got a pile of carbs and also know what youre doing and have a way of flow testing.
Im happy to measure the cb175 carbs i have, but thats not really going to help compare the 200 to the 175
 

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Thanks Simo and Sprint,

Another thought, at the back of the FSM it quotes the CL175K7 power output as 16bhp at 9500rpm. Could that be a clue ?

Richard
Couple comments -

The power output for the CB 175 K5 thru K7 is reported as 16bhp @ 9,500 rpm. The CL175 K5 thru8 K7 are rated 20 hp at 10k rpm (not 10.5k rpm). REF: thread #127 http://www.hondatwins.net/forums/1-...5-k5-rebuilding-miss-daisy-13.html#post318223

I find it hard to believe though the CL 175 exhaust pipes produces more bhp than a CB. The FSM for the K5-K7 is poorly written; lots of wrong/misleading info. Its the worst manual I have reviewed by far compared to any other of the small 41mm stroke honda twins (125/160/175/200 all model years).

NOTE: The CB/CL175 K0 thru K4 FSM has the 20 bhp @10k rpm specification

Other factors such as the cam can affect the performance numbers... REF: thread #6 (175's come in 3 flavors) http://www.hondatwins.net/forums/28-wanted-parts-bikes/43709-wtb-sl-175-camshaft.html#post346015

Reviewing the CB200 FSM page #85 cam changes even further (different from the 175's). Reviewing these specs you can pretty much determine the better breathing cam. As you know the 200 cams are not directly interchangeable due to tooth count of the cam chain... just mentioning that for others reading this post so they don't blindly go out and try and make that swap (I know you were already aware of that)

The restrictive rpm on the tach "may" have been purposely reduced on the 200 engine for a number of other reasons

- The cylinder bore is larger; increased piston & piston pin (15mm pin) weights; acceleration forces are higher (g's)

- Longer connecting rods... more weight to rotate around

- The stock rings (fat compared to today's rings) rub more cylinder surface area... friction/heat "may" have become an issue @higher RPM's (I kinda doubt this one as the CB350 10.5k rpm engines have the fat rings and cover a larger surface area.

Carbs are kind of an interesting subject on their own in that a CB125 twin has the largest carb of all models within this 41mm stoke series with an 11k rpm limit @15 bhp. I'll leave that subject to the pro's as I am pretty much carb stupid...

Those are just thoughts on other potential reasons for lower power output specifications for the 200 (beyond the carb). There's probably more/other reasons for the reduction in rpm & power output

Carry on with the investigation; starting to wonder what you actually received though :)

Cheers
 

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Discussion Starter · #23 ·
The CB200 pistons are much heavier than the CB175 items. That, and the longer (same stroke) rods, which must weigh more, are the principal reasons in my view why the 200 makes the same real world power as the CB175, at lower peak rpm. And the CB200 cam, of course. I'm now disinclined to think that the carbs make much difference, if the parts I have here are representative.

I can only speak for what I have ridden, and can see in front of me.
 

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Discussion Starter · #24 ·
I have cleaned and rebuilt the CB200 carbs, using Keyster kits from David Silvers.

Fitted these to the 175 engine, using the 175 alloy manifolds. ( I have been running with the CB200 rubber manifolds and 175 carbs for a little while now, just as an experiment).

After some initial problems with the float valves sticking shut, leading to an embarrassing breakdown in the middle of some roadworks, I got the bike running. I fitted the floats and fuel valves out of my 175 carbs, got the fuel flowing again.

And it runs really well. Starts, idles, and revs to 10K in the lower gears, no flat spots. Pulls better than it did on the (dimensionally identical, in my opinion) 175 carbs. I'm running the 200 jetting, 88 mains, 38 pilots, needle in middle position.

Took it for a 30 mile ride in todays hot weather. I was worried that I might be running too lean, given the snappy way in which the engine picks up now, but a plug check this evening showed the plugs quite black and sooty, not what I'd expected. I am running CB200 air filters, rebuilt using RamAir filter foams.
 
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Discussion Starter · #25 ·
Still running well on this setup. In fact, I'd venture to say that it is running the best ( and fastest ) it ever has been for me.

Bit surprised to find it going onto reserve at 85 miles from fairly full, think the fuel consumption has increased. Plugs still sooty, and a slight hesitation around the 3-4000 rpm mark, so I lowered the needles one notch from mid position, clip in 2nd notch from top. Two of our UK CB200 owners reported the same observation in the past, makes me think it's the carbs rather than specific to 200 or 175 engine.

Just done 30 miles this morning, running well. Several issues now addressed. Before, bike was very cold blooded, always needed choke to get it running, needed choke until engine warmed up. Tickover set on cool engine to 1200rpm would rise to 2000rpm once hot.

Now, it starts without choke in our English summer, tickover remains stable regardless of engine temperature, exactly as I remember my first (brand new) CB175 was. I'm now firmly convinced that these UK CB200 carbs are identical in terms of casting and venturi size to US spec CL175 carbs, apart from the brassware.
 

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Hi Richard. Re the overflowing carbs in my post I have managed to get my hands on a pair of CB200 carb bodies so will do as you have done above fitting all the jets etc from my old carbs and hopefully curing the flooding problem.
 

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Discussion Starter · #27 ·
Hope it works out.

Mine is still starting and running better than ever, but I have the CB200 jets and needle from the Keyster kit fitted.
 

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I read somewhere that the rubber inlet manifolds were to prevent the carb vibrating which causes them to give a rich mixture (when they are vibrating) This in only what I read somewhere and "NOT" my opinion, It would if correct probably only show up on a dyno as a slight loss of power but not be noticeable when riding.
 

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Discussion Starter · #29 ·
Just saw this UK CB200 sales brochure on Ebay.

20mm carbs .....

cb200 carbs.JPG
 

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Hi Brush. If you have no takers for the carbs I will have them off you.

Cheers. Martyn.
 

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Heres the carbs, there are no tops (Richard did you use the 200 slides etc and needles sorry if I missed the post that covers that bit)
connecting rod adjusts (not seized), and bowls come with original gaskets
Alex where in the world are you and I can work out a shipping price (will be tracked)
Cowboy57 you are standby if Alex doesn't want them

Phil



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apologies but it won't let me edit the above post

"R" clips on the choke arms not split pins (added bonus in my eyes)
 

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Discussion Starter · #37 ·
The CB175 carb tops and float bowls, throttle slides, needle valves and floats etc etc are all interchangeable with the (UK specific?) CB200 parts.

Same main casting, minor differences in drillings for air jets, obviously the brassware and throttle needles are different.

CB200 rubber manifolds are shorter than the CB175 alloy items, but are inter changeable. I have a suspicion that the rubber trumpets on CB200 air filters are slightly longer to compensate for this, but still fit, maybe 'concertained' up a bit.

CB200 manifolds come ready tapped to take vacuum carb balancers.
 

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Hey brush,
I think if Cowboy has an immediate need then he's better off getting them, I have a few other things (3 kids on the run up to Xmas) I need to spend cash on right now!


Sent from my iPhone using Tapatalk
 

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Thanks for that Alex. Much appreciated. When you get round to your project let me know if you need anything. I have a few bits and bobs left over from when I restored mine.

Cheers. Martyn.
 
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