New Carb...OEM or Chinese

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cornflakejoe

Member
My CT70 already has a Chinese carb on it that is very gummed up from years of the fuel not being drained. I still have the OEM carb in a box, but its in the same shape.

Should I go for a new Chinese carb for my 91 CT70, or should I spend the extra money on an OEM Made in Japan carb?

Its about $120 for the OEM vs $40 for the Chinese.

Are there any such things as "performance" carbs or Jet Kits available for these these carbs to improve the performance, or is it just a waste of time?

Thanks!
 
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69ST

Well-Known Member
You may well be able to clean & rebuild the original, as long as the casting isn't seriously pitted/oxidized.

For my money, I'd use a stock Keihin on a stock motor. Parts are readily available, including rebuild kits & tuning jets, plus you know what you're getting. Not that a cheap carb cannot work well for you, just my preference for known, OEM, quality.

FYI, if you're not concerned about purist originality, you could just as easily source a Keihin for an earlier (K0 - `77) model. As I recall, these have more adjustments.
 
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cornflakejoe

Member
racerx said:
You may well be able to clean & rebuild the original, as long as the casting isn't seriously pitted/oxidized.
Click to expand...

My original one is in pretty rough shape, oxidized big time. I don't imagine a rebuild would fair well.

racerx said:
For my money, I'd use a stock Keihin on a stock motor.
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I've heard that some Chinese carbs can cause the engine damage by either not being designed for the model with incorrect jetting, or just poor quality and fuel supply.

racerx said:
FYI, if you're not concerned about purist originality, you could just as easily source a Keihin for an earlier (K0 - `77) model. As I recall, these have more adjustments.
Click to expand...
Neat. Will it bolt right up? Do I need a different throttle cable? I assume the newer model would have less adjustments because of emissions.
Any idea what the other adjustments that might be available on the older model carbs than the newer ones?
 
6

69ST

Well-Known Member
cornflakejoe said:
I've heard that some Chinese carbs can cause the engine damage by either not being designed for the model with incorrect jetting, or just poor quality and fuel supply.


Neat. Will it bolt right up? Do I need a different throttle cable? I assume the newer model would have less adjustments because of emissions.
Any idea what the other adjustments that might be available on the older model carbs than the newer ones?
Click to expand...

I'm no fan of cheap PRC carburetors, but engine damage has to do with an air:fuel ratio that's off-the-chart, not necessarily the carb selected. It's just easier to source parts for known carbs such as Keihins & Mikunis. Many Chinese carbs seem to deliver satisfactory results for their owners. I think longterm. What about 3 years from now when you need a part to return that carb you like to tip-top shape?

You're right, emissions-compliance spelled the end of easy tuning. I don't believe the `90s vintage carbs have adjustable jet needle height, not sure about the idle air bleed either. Earlier models have both. Unless the manifold flange is different, at the carb end, this should be a bolt-on. They're all 16mm metered fuel leaks. I'd also expect the original throttle cable to work, as well; if not, cable length can be tweaked, adjusted and/or custom-tailored.
 
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b52bombardier1

Well-Known Member
I also like the OEM Keihin carbs for all of these bikes because it seems like there are more parts available in better sizing and jetting. Yea, you pay a little more to rebuild it but you are getting more flexibility and adjustments - it's worth it. I do have two of the PRC carbs but that was before I learned my lesson.

Rick
 
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69ST

Well-Known Member
cornflakejoe said:
Thanks kindly,

Is there such a thing as a "performance" carb for these things, or is it just a waste of money with a stock motor?
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That question could generate a long, detailed, explanation. The Cliff's Notes version is that a carburetor is either a flow restriction (undersized) or it's not. You don't so much gain hp by sourcing a "peformance" carb as lose hp from an undersized unit. Anything larger than the diameter of the intake port is grossly oversized. Oversized can be worse than undersized, throttle response will be lame and you'll spend more time chasing lean spots than anything else.

If you're running the complete stock setup, including the airbox, there's little-to-nothing to be gained going larger than the OEM 16mm metered fuel leak. With a few accompanying changes, upsizing to 18mm might give you a few more mph. There's probably more to be gained by cutting-out the restrictor inside the rear boot, if yours has one. You might be able to make a 20mm carb work, it'd be a marginal proposition on a bone stock 72cc 3-speed motor. Keep in mind, the larger the carb, the harder it will be to tune for smooth throttle response.
 
M

MCM

Member
"Its about $120 for the OEM "

I ordered OEM carb #16100-098-731 from a Honda parts dealer, they said it was in stock then 2 weeks later my VISA was refunded?

Anyone have a source for a new OEM carb for my 73 K1?
I am finding #16100-098-731 is Obsolete?
 
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Epic_username

Epic_username

Member
What I did was I got a brand new 19mm keihin. I had a motorsports store order it in for me and it was about $50. It revs up nicer, and I gained about 3-4 mph. I dremeled the stock intake a bit bigger and polished it. I had to richen the a/f mix when I got it but only because the motor it was on had a massive airleak around the spark plug. All in all Im happy with it, its a nice match to a bone stock 3 speed.

Make sure its a real keihin though, knock offs are usually a bit smaller than they say they are.
 
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cornflakejoe

Member
Epic_username said:
What I did was I got a brand new 19mm keihin. I had a motorsports store order it in for me and it was about $50.
Make sure its a real keihin though, knock offs are usually a bit smaller than they say they are.
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Sounds like a fair deal. I'm assuming a bit higher fuel consumption with the 19mm?

Is your carb made in Japan? Where did you find it for $50? I found most are asking near $50 for a PRC carb!

Thanks guys for all the replys,
 
Epic_username

Epic_username

Member
It was a place in surrey called KTM powersports. I think he ordered it from his supplier and I dont know it.
I wouldnt know about fuel consumption, my bike was already a pig on gas because it leaked around the sparkplug, and I rev the crap out of it.
Im pretty sure its made in Japan, but dont bet on it.
 
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69ST

Well-Known Member
cornflakejoe said:
Sounds like a fair deal. I'm assuming a bit higher fuel consumption with the 19mm?

Is your carb made in Japan? Where did you find it for $50? I found most are asking near $50 for a PRC carb!

Thanks guys for all the replys,
Click to expand...

As long as you get the air:fuel ratio right (i.e. correct mixture) and the carb isn't oversized to the point where fuel atomization degrades, fuel consumption should not increase.

Pretty sure that there's no such thing as a 19mm genuine Keihin. If it's a knockoff, as I suspect, it's probably closer to a true 16mm...which is a good thing on a stock motor.
 
M

MCM

Member
Not sure if Keihin is making carbs in China now or not?
Or if its stamped Keihin?
Does it look like any of these?
If it works for you great!

RH CHOKE KEIHIN PB 19MM CARB HONDA CRF CT 70 ATC ATV 1 | eBay


KEIHIN 19mm Carburetor of High Quality with Cable Choke for 110cc ATV, Dirt Bike & Go Kart [N090-007] - $37.95 : , Chinesemotoparts.com

19MM Carburetor for Dax/CT70 and Chinese

19mm Honda CT70 MINI TRAIL Carb CRF SL PASSPORT 70 CA21

RH CHOKE KEIHIN PB 19MM CARB HONDA CRF CT 70 ATC ATV 2 on eBay!
 
As an eBay Associate we earn from qualifying purchases.
C

cornflakejoe

Member
Thanks guys.
I am doubting that a real Keihin carb would sell for under $100, and i'm pretty sure they are made in Japan.
I'll have to do some hunting and see what I find.
 
ctbale

ctbale

Member
I have got a few carbs that say keihin, and mad in japan, both cast in the carb, but a sticker on the bowl says made in china, if its cheap, its a copy. but they work great.
 
6

69ST

Well-Known Member
cornflakejoe said:
Thanks guys.
I am doubting that a real Keihin carb would sell for under $100, and i'm pretty sure they are made in Japan.
I'll have to do some hunting and see what I find.
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Probably more like a $70 starting point, depending on the model and vendor.

ctbale said:
I have got a few carbs that say keihin, and mad in japan, both cast in the carb, but a sticker on the bowl says made in china, if its cheap, its a copy. but they work great.
Click to expand...

Copyright/trademark laws don't mean much in PRC. Someone could contract to have any name, or logo, cast into a part. A fake Keihin could be seized as contraband here, it's highly unlikely. That said, what works...works; just know what you're getting beforehand.
 
OLD CT

OLD CT

Well-Known Member
Anyone interested in the ebay webllc carb should get the left hand choke and ''dual fuel petcock'' on the left side.so you wont get burned when turning the fuel off by the exhaust.the right hand choke and single inlet ''like pictured'' versions were the first to hit the market and now you have the option of not getting burned.this webllc carb is ten times better than a shengwey in the bore up kit from dr atv.
 
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Epic_username

Epic_username

Member
My keihin 19mm is right hand choke.
My hands are pretty bulky, and I dont get burned by the exaust. Mine is single inlet, on the left side, with no petcock.

Ive been meaning to put one on, fuel filter too.

I just had someone check for me, my carb really is 19 mm
 
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