Oko 21mm jet size for sea level

Ceeskiroy

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Joined
Oct 24, 2021
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14
This screw? That is the power jet access, it normally wouldn't stop the engine from starting but being lean all ready this would for sure make it more difficult, Treatland would have the part, or any small 6mm cap screw would work.
Carb's are carb's they all basically work the same and require being jetted/tuned to the application, this carb one of my favorites has 5 points to be tuned the pilot jet, air screw, needle, main jet and the power jet. Tuning starts from the bottom up pilot jet first and the air screw, with a proper sized pilot jet the air screw should be around 2 turns out and idle properly then the needle is for tuning the transition from idle/pilot jet and upto 3/4 throttle then it's the main jet upto full throttle and the power jet adds fuel at WOT when the velocity is high enough to pull the extra fuel, and this is to help when on the pipe so as not to go lean at peak rpm.
You could try a pumper/diaphragm type carb as it needs no jet changes but you still need to tune it adjusting both the slow and high speed needles (much easier) but then they need a pulse line fitted to the case or base of cylinder and if the engine flows enough a secondary fuel pump may be required.View attachment 160100
Yes this screw. So this screw missing wouldnt cause a air leak for the intake? Is this where the jet is located? Is this just a screw that I could stick a 6mm bolt into or is it a special design? Is it meant to be an adjustment or just a access screw for the jet? I was adjusting it maybe why it fell off.
 

DAMIEN1307

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Guess that means this forum is for boredom.
You need to be patient...everyone here is not knowledgeable on every type of motor, bike or carbie...All are unpaid volunteers...Today is also Saturday, at least in the US and Canada...Family day for many here and they may not be online right now...hang in there, Your questions are there and those that know about OKOs wiil get back to you...my expertise is on the stock NT carbies and how to adjust them...once you go to modifications and parts, you need the big boys that specialise in that field...DAMIEN
 

Karl Snarl

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Sep 20, 2019
Messages
3,173
You need to be patient...everyone here is not knowledgeable on every type of motor, bike or carbie...All are unpaid volunteers...Today is also Saturday, at least in the US and Canada...Family day for many here and they may not be online right now...hang in there, Your questions are there and those that know about OKOs wiil get back to you...my expertise is on the stock NT carbies and how to adjust them...once you go to modifications and parts, you need the big boys that specialise in that field...DAMIEN
Guess that means this forum is for boredom.
I don't use those carbs. I use saw carbs. I have one bike with an NT carb, rest are saw carbs, for ease of tuning, more power, they are cheap, no jets to pull, no gas smell, and easier than throwing a turd at a bird to repair. They also save a ton of space, and there are literally thousands of different models to choose from. Parts can be found at most small engine repair shops when you have no internet too.
 

Street Ryderz

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Oct 14, 2016
Messages
4,318
Yes this screw. So this screw missing wouldnt cause a air leak for the intake? Is this where the jet is located? Is this just a screw that I could stick a 6mm bolt into or is it a special design? Is it meant to be an adjustment or just a access screw for the jet? I was adjusting it maybe why it fell off.
Guess that means this forum is for boredom.
No it wouldn't cause air leak that would really effect the idle as it relies on higher velocity before it work's. Yes just a regular screw and it's 5mm not 6mm sorry I was wrong there, but yeah any short 5mm with 1.25 thread pitch I think may wanna double check that, and yes it's just the access to the jet inside there. Usually carbs come jetted from the factory pretty close to the right ones based on the volume but every engine is different and fine tuning and final jet size will vary from engine to engine and this is way people will say they can't tell you what jet works best for your application. The biggest problem is that the use of a reed requires larger pilot jets than what comes stock and again every engine is different with different requirement's so we can only really offer advise that helps to get you started, and as I said before starting big/large and working down is much easier and doesn't hurt the engine where as being lean can and will. So best thing for you is put the bigger pilot so you can get a workable idle and go from there, we can help along the way when needed just have to be patient some times (I know that sucks) in getting a reply because life tends to take priority over getting to come on the forum, sometimes I don't get to get on here for a few days but usually I'm on pretty often to help if I can.
 
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