21mm oko Jetting ?

[Simonsr50]

Im running an 01 elite with corsa, pg long, 21mm oko, ct mani dual reed intake, and gears and clutching. wondering what jetting setup to start with? any help id appreciated. Main? NEEDLE? PILOT? looking for safe setup.

[Mystic]

There really isnt any magic combination I would say start with a 48 pilot and a 130 main and work down from there probably somewhere around 120 but you want to start rich, the needle will need to be adjusted to get rid of any sputter low and midrange. Plug chops and or cylinder head temp gauge required to get it just right

[Wheelman-111]

Greetings:

Everything Mystic said is correct, but to get a bit closer: Consider I was running a 48/125 combination in my 26mm OKO. Generally, smaller-diameter carbs take smaller jets. I seem to remember Bakaracer suggesting something like 118 or 115 in a 21mm for someone. If you don't want to foul a plug and wish to decrease the number of Bowl Dropping sessions, you might consider starting at something like 45/120 and see what the spark plug looks like. If the scooter smokes a ton and burbles and four-strokes, you can safely go down from there. This assumes no air/vacuum leaks and a sound engine otherwise. Trial-and-error is better than any Online advice anyone can give you, but you never want to start too skinny - danger of overheating before you can shut it off.

[Simonsr50]

I have tried almost everything. I have tried 122 main down to 108 and the CHT still gets to 400. It also seems like if I got big on main jet the low end needle position has a sputter. Te only Time it doesn't sputter is with like 110 main or lower and with clip in middle position or clip one up(leaner). If I make it so the CHT's stay down it bogs and sputters like crazy. I feel like I need a different needle. Any thoughts on different needles?

[Wheelman-111]

Greetings:

What Pilot jet do you have installed? Your post described the experiments you've tried with the MAIN circuit and the Main jet needle but I see no mention of your Pilot size. Sometimes THAT's the problem. With a really big pilot, which in your case may be a 46 or so, you can get away with a smaller Main, or lower the needle to lean.

Do the temps go high right off idle? Does the temp stabilize when the throttle is open but spike up when you close the throttle? That'd be the symptoms of a too-small pilot. Whatever's in there now, go up a size or 2 and try 118 or so main. Z50RGhost has a lot of testing time with an OKO 21/Corsa setup. Maybe hit him up for more instructions?

I have my own jetting guesswork to do in another thread. Anybody ever even HEAR of a VM26?

[Mystic]

what spark plug are you using and have you done a leak down test to make sure you have no air leaks anywhere? those ct manfolds have a habit of not sealing off properly. also do you have the oil pump plugged or what?

[Simonsr50]

I have a 42 pilot that I just drilled out a little bit with step bits but it seems to have made it worse. Would changing my main jet effect anything with pilot circuit? I feel like I'm to rich down low and too lean up high. My idle temp is like 220f and if I'm WOT and let of te motor cools down quick so I guess I'm rich down low. But then again I have backed out air screw to 2.5 turns and it doesn't make it better. I'm gettin *.

[Wheelman-111]

Greetings:

You can't really drill out all the little side channels in a Pilot and hope for accuracy. I recommend you procure a proper set of Pilots and remove that unknown variable. Z50RGhost can help you get close, but not with shrapnel for jets.

[Simonsr50]

k i tried a 40 pilot and it seems to be a little better, more tuning planned today. I'm running ngk b8hs

[Simonsr50]

Does anyone use a different needle on the 21mm oko?