Carby DIO reed valve/OKO carb tuning advice

Joined
Mar 21, 2020
Messages
71
I know the OKO isn't really everyone's favorite as far as a China Girl carb, but I needed a new cylinder after a wrist pin circlip decided to disintegrate and absolutely destroy the bore. Admittedly I didn't look very hard, but the only easily available cylinder I could find was the kit that comes with a modified cylinder, DIO reed valve, and (knockoff) OKO 21mm carburetor. I figured I'd give it a shot and if it didn't work I could always get a different carb, like a Mikuni, Dellorto, or even a 19mm (genuine) OKO.

I've already installed a windowed piston and a replica MZ65, and I plan to add a CDI with adjustable timing, like Jaguar's, so as not to have to mess with the magneto. I've also got a jet kit.

So my question is: Does anyone have any advice with getting these set up, like where to start with jets and timing, or any mods that should be done? As far as spark plugs, I have a couple NGK B7HS (the parts store was out of B6HS); will these work, or should I get some with a different heat range? I'm at about 2500 feet above sea level, elevation wise, and have a 66cc motor.

Also: The carburetor has a nipple on the bottom of the float bowl, with a long hose on it. There's also a barbed fitting on the intake pipe. I'm assuming the two are supposed to be connected? I'm not positive though.

Thanks in advance for anyone's help.
 
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Chainlube

Well-Known Member
Joined
Jan 5, 2020
Messages
2,793
I know the OKO isn't really everyone's favorite as far as a China Girl carb, but I needed a new cylinder after a wrist pin circlip decided to disintegrate and absolutely destroy the bore. Admittedly I didn't look very hard, but the only easily available cylinder I could find was the kit that comes with a modified cylinder, DIO reed valve, and OKO 21mm carburetor. I figured I'd give it a shot and if it didn't work I could always get a different carb, like a Mikuni, Dellorto, or even a 19mm OKO.

I've already installed a windowed piston and a replica MZ65, and I plan to add a CDI with adjustable timing, like Jaguar's, so as not to have to mess with the magneto. I've also got a jet kit.

So my question is: Does anyone have any advice with getting these set up, like where to start with jets and timing, or any mods that should be done? As far as spark plugs, I have a couple NGK B7HS (the parts store was out of B6HS); will these work, or should I get some with a different heat range? I'm at about 2500 feet above sea level, elevation wise, and have a 66cc motor.

Also: The carburetor has a nipple on the bottom of the float bowl, with a long hose on it. There's also a barbed fitting on the intake pipe. I'm assuming the two are supposed to be connected? I'm not positive though.

Thanks in advance for anyone's help.
The barb on the intake is for a boost bottle, just cap it off, boost bottles do nothing for performance. The hose on the bottom of the carb is an overflow, just cut it to a suitable length, and feed the hose to the ground.
 

Triplehelix

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Joined
Oct 31, 2020
Messages
3
With my dio valve motor I went through 2-21 mm oko's. I tried everything( even drilled a hole in one to supposedly help flow). Put a 24 mm Nibbi racing carb on and it idled and ran right out of the box. I am finishing the carb tuning process. At 3300 feet 39 idle jet, 102 main jet.
 
Joined
Mar 21, 2020
Messages
71
The barb on the intake is for a boost bottle, just cap it off, boost bottles do nothing for performance. The hose on the bottom of the carb is an overflow, just cut it to a suitable length, and feed the hose to the ground.
That helps a lot, thanks for clearing that up!
With my dio valve motor I went through 2-21 mm oko's. I tried everything( even drilled a hole in one to supposedly help flow). Put a 24 mm Nibbi racing carb on and it idled and ran right out of the box. I am finishing the carb tuning process. At 3300 feet 39 idle jet, 102 main jet.
Were the ones you tried genuine OKOs (with the Taiwanese flag on the box) or knockoffs? If knockoffs I might just bite the bullet and get the 19mm genuine OKO.

Thanks for your input, I appreciate it.
 

Triplehelix

New Member
Joined
Oct 31, 2020
Messages
3
No they were knock offs I am sure. One came with kit, 1 was from the rain forest called amazon. $35 should have clued me in. Neither were tuneable for me. But I am not a super experienced 2 stroke guy tuner. Spend the $100 and get a real oko or pwk in my opinion. I am no expert and I am just a guy trying to tune this motor.
 

Chainlube

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Joined
Jan 5, 2020
Messages
2,793
No they were knock offs I am sure. One came with kit, 1 was from the rain forest called amazon. $35 should have clued me in. Neither were tuneable for me. But I am not a super experienced 2 stroke guy tuner. Spend the $100 and get a real oko or pwk in my opinion. I am no expert and I am just a guy trying to tune this motor.
Do you have a link for the carb? Just wondering what it would have over a Mikuni, Delortto or NT?
 

GreasyChris

Well-Known Member
Joined
Jan 3, 2019
Messages
1,493
The oko are easy to tune, even the clones. I've never had to drill one out. I have real oko and clones neither need drilling. Jetting is dependent on your altitude and weather conditions. However I would most likely say you're going to need a 38 pilot jet and around a 105 to 110 main with your set up. Here's a step by step tuning instruction. Simple and straight forward.
 
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