Honda Spree and Elite 50 Forums

setup is a 2001 Elite 50 with a polini corsa 72, piarel exhaust,zx trans, stage 6 intake, yellow contra spring, polini variator, 5 gram weights, kind of having issues getting this thing tuned properly have a weird midrange problem at light throttle cruising at about 35-40 and maintaining speed starts to make a weird noise kind of like its running lean but the plug reads good and cylinder head temp isnt hot. im currently running a polini 28mm with a 116 main, 45 pilot and needle one clip lean the throttle response isnt the greatest thinking that maybe i should be looking into a smaller carb?

28mm is too big for 72cc.....Ive seen people use 19mm, 21mm and 24mm with their Corsa all with great success....Ive also seen somebody run a 19mm Mikuni on his 90cc ATV and it ran like a dream. I suggest getting a smaller carb in the 21mm area, give or take. Some sites suggest using AT LEAST a 17.5mm carb with the Corsa but I wouldnt go that small, especially with your other mods.

When it comes to carbs, bigger is not always better, you lose vacuum the larger you go, you'll want to find a sweet spot for your specific engine. I'd go with a 19 or maybe a 21mm for a 72cc setup. But no bigger then that. Not sure, but guessing for what you have, a 19mm would probably serve due diligence.

I am currently running a 26 on my corsa set up and I think its to big. I have run a 24 on mine with great success and will be going back to that set up very soon. even with a great port job from oneman I know guys that are only running 26 on theirs. I am struggling with jetting mine currently running a 118 mj with a 38 pilot clip all the way down. if I go any leaner it runs like crap and currently am running as rich as I can as I can find any bigger mjs that arent in the 130s. I have literally tried every combo and cant find the a happy medium. with a 24 I can have it dialed in no time. its funny how differently the exact setup with a different carb can act so drastically different. its very strange because my temps are super low like in running rich but if I go any leaner it runs like crap. tried new plugs and every jet combo I can think of to no avail. so solution is going back to a 24. I think personally the 24 is perfect for the unported corsa. I have had my bike 72mph @10k rpms with a 24mm.

24mm...

24mm runs great on that setup. The 21 & 23mm polini cp's are also great carbs for a 72

Greetings:

Ten years or more ago, our Hawai'ian brothers did a lot of the pioneer work tuning these things. There began the affection for the affordable OKO clone of the Keihin PWK 28mm prototype carb. Other sizes, as I recall, were hard to obtain, but vendors quickly caught on to that fact and filled the need.

I too ran a Corsa 24mm carb with primitive tuning "skills" and never broke 70MPH. (Flash 3.1) Possibly it was a coincidence with better transmission tuning, but I finally went over 71MPH shortly after installing a 26mm OKO. I do recall it was rougher in the low-end and midrange, but there's no denying it went a bit better on top. Whether or not the bigger carb was the reason is in question.

I'd have to agree. Running 28 OKO is oldschool. was all the rage back then, but its def overkill nowadays.
I'm guilty of a Corsa/28OKO/PG Long setup myself, and thoroughly loved and enjoyed it but it was PITA to dial in. But it could be done.

My best with the 28 OKO:
Pilot = 55
Main = 142
Needle = 1clip rich from middle
A/F = ~1.5turns out

Polini's are more fuel efficient from what I hear, so prob won't help you much. Unless there's an OKO to Polini converstion table somewhere..
Was getting like 30mpg with that setup terrible.. loll

In closing, later went to a 24mm OKO then a a 21mm OKO and enjoyed that one the best. Next build, will be trying a Polini CP23
.02