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Post by dude on Jul 19, 2011 23:40:36 GMT -5
My stock carb on mt Zuma is a14mm. I have a 17.5 PHAV, 19 PHBG, 19 ARRECHE. I am using the stock airbox and its a daily driver. I think the 17.5 is the better choice if I gain a little something. What kind of Gains or Losses should I expect on these carbs?
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mccanic
Scoot Enthusiast
Posts: 254
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Post by mccanic on Jul 20, 2011 1:04:15 GMT -5
bad mpg thats about it unless you get a big bore kit and a pipe
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Post by MAReames on Jul 20, 2011 1:34:26 GMT -5
According to his siggy he has 70cc kit but not a pipe.
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mccanic
Scoot Enthusiast
Posts: 254
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Post by mccanic on Jul 20, 2011 7:09:37 GMT -5
did see that thanks
and the zxr is a pipe.
i would go with the 17.5 PHAV, you will get better throttle response.
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Post by 90GTVert on Jul 20, 2011 7:37:35 GMT -5
Going to a larger carb, you might pick up a little power at higher revs. Sometimes you lose a little throttle response, but with 17.5-19mm, I don't think it'll be much of an issue. The bigger carbs can help keep your cylinder cool a little better. Fuel economy should decrease as venturi size increases. I don't think any of these efffects will be drastic with these sizes. I think any of them would be a good choice, although I think the Dellorto carbs are better than Arreche, or at least I like them better. Now if you stuck a big 28mm on there like some folks do, that's when you'd really see that throttle response problem and fuel economy drop off. I watched a vid of a scoot with a 28mm and a 70cc sport cyliner and pipe. Lag was pretty bad. It would have to pull incredibly hard to be worth all the lag, and even then it would still annoy me every time I hit the gas and looked at my watch. lol
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Post by 2strokd on Jul 20, 2011 7:58:58 GMT -5
Ran a 28mm on a mild 70cc with the results Brent posted. I got about the same overall ET in the 1/8th but it was a pig off idle in comparison to my 21mm Dello.
When i went from my stock 18mm Mikuni to my 21mm Dello i got better everything! Mot saying that is always the case but i got better mileage, response, top-end, reliability, you name it.
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Post by Enviromoto on Jul 20, 2011 14:59:01 GMT -5
My 21oko is still a bit of a dog off the line, its a very mild 70cc kit and prima pipe though so some more aggressive kits will have better luck. I would say start with the 17.5 and go from there.
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Post by 2strokd on Jul 20, 2011 16:40:39 GMT -5
Just needs tuned better. What are the port durations on the mild 70cc kit you installed J?
What kinda of Prima pipe? Just curious as to if the pipe matches the durations and things even match up well with your set-up? That makes a big difference! You saw me at TnG last year. Mine was a dog off the line from not enough transfer port timing and too little RPM before clutch engagement. Those two little things made for a turd on the track first 60ft.
Ide run that 21mm PHBG Dello. Great carb and i bet you will get the best all around results with that carb. With the right tune that is. Thats just my stink about it lol. Hope the best for whatever you chose dude!
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Post by stepthrutuner on Jul 20, 2011 18:56:01 GMT -5
I vote the 19 PHBG. My 21 PHBG pretty much does nothing the last 1/4 of throttle travel. (48mm TP Trophy Series, 30g roller mass, yellow contra, modded MK SP pipe, revving low to mid 10s.)
I think a 19 would be perfect for me.
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Post by 2strokd on Jul 20, 2011 19:12:17 GMT -5
His is a Arreche 19mm step
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Post by stepthrutuner on Jul 20, 2011 19:47:08 GMT -5
My stock carb on mt Zuma is a14mm. I have a 17.5 PHAV, 19 PHBG, 19 ARRECHE. I am using the stock airbox and its a daily driver. I think the 17.5 is the better choice if I gain a little something. What kind of Gains or Losses should I expect on these carbs? He stated he has both. The 17.5 designation should read PHVA. |
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Post by jmkjr72 on Jul 20, 2011 21:57:19 GMT -5
im a fan of the arreche carbs i have had great luck with them and i ran a 19mm on my zuma till i got the efi set up
with the trophy and a street build and a zx pipe you realy ahve no need for anything bigger then the 19mm
with the 19mm i would expect about 35 mpg the 17.5 will praobly get you about 45 and im guessing from personal expaeriance you are getting about 55 with your oem carb right now
with any of these carbs if you get a reed block make sure to get one with a stuffer to keep the volicty up
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Post by dude on Jul 20, 2011 23:37:02 GMT -5
Sorry it is PHVA and not a PHAV. I am leaning toward the17.5 its a daily ride. Mileage. I am using a Adige reed cage and its a small cage like stock.
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Post by stepthrutuner on Jul 20, 2011 23:46:43 GMT -5
I think you'll be happy with that. I've got an old one for parts should you need it.
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Post by reveeen on Jul 21, 2011 2:49:23 GMT -5
Intake velocity/volume.
You pick your carburetor size based on estimated intake velocity/volume and experience.
There are so many factors it would make your head spin.
Generally 70cc Zuma's seem happy with up to a 20mm carburetor. If your operating rpm is low (under 7000), your clutch "hits" early, and your rollers heavy, then you pick smaller. I *think*, out of the carburetors you have, you will get the best results out of the one you personally are able to tune the best/easiest (because they are all in the ballpark size). *Best/easiest* meaning: the one you are most familiar with, and the one where the parts (jets/possibly needles) are the closest to hand.
As far as "mileage" goes: assuming the current 14mm carb is the "bottleneck" in your current system, by increasing that size you will be increasing the volume pumped through your motor until the system hits the next "bottleneck". So, yes, expect your mileage to decrease, but only if/as the volume increases (provided you get your new carb tuned in like your old one).
When attempting to create "performance", the system (your engine), must be considered as a whole. From carburetor size, to reed valves, to cylinder porting, to exhaust, it ALL plays a factor in your end result.
This is why, when considering "performance improvement", I start at "the back end" (exhaust), and move forwards, with increased carburetor size being last on my "list".
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