e50 + polini - benefits of 21mm?

Right now I have a e50 with a polini kit, the engine case has been case matched and ported and it has a 15mm bing with the 2 reed valve intake that came with kit. Whould i get a big perfomance gain with upgrading carb to a 21mm with a 4 reed system?

Re: e50 + polini - benefits of 21mm?

really fast.

Re: e50 + polini - benefits of 21mm?

I've never run the bing setup with the Polini kit, but I have run several bikes with the 21mm setup. Please note that the tuning is MUCH more difficult and much more of a headache. BUT once its tuned it rarely needs to change (probably only needs to change for weather) Be confident in your knowledge of the PHBG or know someone that can give you good advise before you take on the project.

MUCH MORE DIFFICULT to tune!

Re: e50 + polini - benefits of 21mm?

I'm currently running a Polini, 4 pedal, and a 21 phbg carb and I wanted to ask what kind of gas mileage you guys are getting. I knew building this moped would mean I would get pretty bad mileage but it seems that I can only go about 20-30 miles on a single tank of gas, is this normal?

Re: e50 + polini - benefits of 21mm?

woof. i run a 19mm on the same setup on a Newport and I get 60 mpg, or about 45 miles on a tank.

Re: e50 + polini - benefits of 21mm?

i'm getting ~70mpg with my 15 bing.

Re: e50 + polini - benefits of 21mm?

Wade, I've noticed the same thing. 30 miles per tank, maybe 40. Then again I've been trying to get it dialed in so I waste a lot of gas changing jets.

Re: e50 + polini - benefits of 21mm?

what makes it so hard to tune?

Re: e50 + polini - benefits of 21mm?

there are quite a few variable on the phbg.

simple carbs tune with what 2 variables?

the phbg has 3 or 4. it can be a hassle

Re: e50 + polini - benefits of 21mm?

I kinda wish I went with the 19mm instead of the 21mm. E50 Polini matched, etc. Runs really nice with 16x36 but there is a weird transition at half throttle then it's just got stupid pull till you let off.

Re: e50 + polini - benefits of 21mm?

) Cupermcnewbster ( /

I ran a 21 forever, then switched to a 19, then tried to go back to 21 and couldn't dial it in just right. So a 19 might be a little easier or I could be talking out of my ass.

Expect worse mileage, much better low end, and maybe 2-3 mph up top. Totally worth it in my book.

Re: e50 + polini - benefits of 21mm?

i have a 4 petal setup that i never used, get at me if you want it. $35 shipped

Re: e50 + polini - benefits of 21mm?

Which make 4 petal? Stock reeds?

Re: e50 + polini - benefits of 21mm?

so, i have a 16 tooth sprocket in the front...i think the back is stock...off the line, its still a little slow, once it gets to 15mph, the case matched/ported polini takes off like a rocket...i haven't gps'd yet, but it has alot of pull after 30

there is a 15mm bing, jet is 88ish? are there ways to get more pull off the line?

Re: e50 + polini - benefits of 21mm?

i'm running a 92 main and a 50 idle jet in a 21mm phbg. I think i'm hitting close to 60 but when i'm cruising at around 25-35 mph it feels like i'm four stroking. Should I lower my idle jet to a 45 or something? When exactly does the main jet take over?

Re: e50 + polini - benefits of 21mm?

Wade, I'd drop your needle one position and see how it feels. Check out the blue and white chart on http://www.mopedarmy.com/wiki/How_To_Tune_PHBG_Carburetors.

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