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View Full Version : Those with 21mm carbs, help me tune!

burnt_toast
04-12-2007, 09:13 PM
I finally managed to install an mrp larger intake manifold custom fit to a 21mm OKO carb on my zip today. I'll do a full write up on how I did it later once I deem it successful..

Spent almost all day installing it only to turn it on and it basically feels like it has no power.. ;;p Doesn't idle either, and literally no power kickin at any throttle.

I'm using a 103 main and an open all foam unifilter, since on my 19mm arreche I used a 100 and it worked well. But since I'm also using a larger manifold might I need to upjet more?

Any other ideas why I don't have any power? Any help is appreciated.
B.A.scoot
04-12-2007, 10:31 PM
What's your needle setting? I have an OKO 24 mm carb, and I'm using a 120 main jet. Are you using carbon fiber reeds?
burnt_toast
04-12-2007, 11:02 PM
What's your needle setting? I have an OKO 24 mm carb, and I'm using a 120 main jet. Are you using carbon fiber reeds?

I WAS using carbon fiber polini reeds, but decided to swap out for the fiberglass mrp ones instead while doing this "upgrade". the cf reeds keep chipping too quickly, so I'm gonna put those in the triton.

Hmm 24 OKO with 120main on a 70cc? And what type of filter? I really think I should probably upjet. Might try like 110-115 if I can find some tomorrow.

thx for your info.
burnt_toast
04-13-2007, 08:27 AM
bumpitty bump for the day. :spiny:
ncsk8er
04-13-2007, 08:44 AM
You need a bigger jet..I was running a 103 in my 90 setup..im moving up to 110 for the 107cc.
burnt_toast
04-13-2007, 12:04 PM
You need a bigger jet..I was running a 103 in my 90 setup..im moving up to 110 for the 107cc.

Hmm, but I'm at 90 right now.
burnt_toast
04-13-2007, 08:05 PM
Played around with it today and got some jets. Got it going with a 110main, but it doesn't feel much faster than the arreche w/ stock manifold, so I'm thinking its still rich. Hopefully I can find a 105main or just tune the carb some more..
burnt_toast
04-15-2007, 09:04 PM
Oh and can someone explain if I'm using the manual chocke properly? Normal operation, the knob is supposed to be closed, and to add chock you pull up? It's what I've been doing but never used a manual chocke before so I'd like to make sure. thx
str8dum
04-16-2007, 07:57 AM
yes thats how it works
OldGuy
04-16-2007, 09:38 AM
Oh and can someone explain if I'm using the manual chocke properly? Normal operation, the knob is supposed to be closed, and to add chock you pull up? It's what I've been doing but never used a manual chocke before so I'd like to make sure. thx

Now I really feel old! I remember when cars had manual chokes. Everyone knew how they worked. .laugh.. .laugh..