Why Disable OKO 24 Power Jet?

[Wheelman-111]

Greetings:

With all the discussion about Dial-a-Jets being added to carbs lately, why isn't the OKO 24's auxiliary system a good idea?

[Trafficjamz]

baka said that it makes our small engines run lean @ 1/4 to 1/2 throttle.

I am searching for the post.......

[Bear45-70]

baka said that it makes our small engines run lean @ 1/4 to 1/2 throttle.

I am searching for the post.......

That is just the opposite of what I experienced with my quads (yeah, I know, bigger engine) but the way the Dial-a-jet works is it pulls fuel sooner than the main jet circuit does, hence enhancing your low end throttle response. This I know is what happens with my quad because the lowly 250 would never spin the tires off the line, but now do with the Dial-a-jet. If you have questions, call them, they know their s*** and will give you the real skinny. I don't know how the OKO system works but I would suspect if what baka is saying is happening that the carb is TOO BIG for the engine. I may have to start a church expounding the virtues and advantages of a smaller carb, rather than the monsters these "Experts" keep recommending. I still need to try to find out the CFM ratings of these carbs so I can use the handy dandy formula that we American educated racers use.

[Trafficjamz]

baka said that it makes our small engines run lean @ 1/4 to 1/2 throttle.

I am searching for the post.......

This is where it came up before.
viewtopic.php?f=3&t=14545&hilit=pink+tube&start=15

[Bear45-70]

For actual jetting the first time, I can see where the system would make it difficult. However installing a Dial-a-jet on an already dialed in fuel system only requires dropping the main jet about 4 to 6 numbers and installing the unit. Since my install was for altitude compensation and I live at sea level, I jetted with the dial-a-jet in the richest position and actually had to drop the smaller 250 engine main jet 8 numbers while the bigger 400 only need 6 numbers. But the marked improvement in low and mid range throttle response was startling. The 400 will even pull the front tires now and for a 700 pound machine, that is impressive with that small of an engine.

[Wheelman-111]

Greetings:

Thanks to TJz for locating the previous discussion.
Quoth-ed Bakaracer:

if has the pink tube from the float bowl to the mouth of the carb,i just disconnect it and jet from there.With it hooked up it makes the midrange run lean on our engines.(1/2-3/4 throttle) thats when the main jet starts its overlap.

And there's where I'm a bit confused. Presuming you start with more jetting than necessary for the setup, exactly how does that lean midrange thing occur? Does it work differently from the Dial-A-Jet setup? Maybe it diminishes fuel from the midrange somehow, to give it back on top?

I respect the experience of those who've tried it, but would like to know how they reached these conclusions. Thanks for any input from OKO 24mm owners.

[nacree]

Wheelman,

I have a OKO 24 with power jet you can borrow to see if you can get your bike tuned well with it- just let me know and I'll send it out.

Nathan
Rio Rancho NM

[Wheelman-111]

Greetings:

PM-ed Nacree.

[wiguy05]

I think what chew-baka is referring to is that most scooterists (myself included) are lazy and simply do a WOT plug to test for correct jetting. With the extra burst of fuel given at WOT from that power jet, the jetting can look spot-on but in reality it is incredibly lean in the mid range 1/4-3/4 throttle. This midrange is where most of our two-strokes spend their lives so burning a motor up is more likely.

[Bear45-70]

Greetings:

Thanks to TJz for locating the previous discussion.
Quoth-ed Bakaracer:

if has the pink tube from the float bowl to the mouth of the carb,i just disconnect it and jet from there.With it hooked up it makes the midrange run lean on our engines.(1/2-3/4 throttle) thats when the main jet starts its overlap.

And there's where I'm a bit confused. Presuming you start with more jetting than necessary for the setup, exactly how does that lean midrange thing occur? Does it work differently from the Dial-A-Jet setup? Maybe it diminishes fuel from the midrange somehow, to give it back on top?

I respect the experience of those who've tried it, but would like to know how they reached these conclusions. Thanks for any input from OKO 24mm owners.

If the OKO actually does what baka says, then it probably is not a power enhancer but a fuel economy enhancer. For year Mercury Marine had on their carbs had a system they called a Back Draft System that actually applied a vacuum to the float bowl to intentionally lean out the fuel mixture for better fuel economy. The vacuum came from behind the throttle plate, via a tube to the float bowl and they used a regular main jet in the bowl vent to control the vacuum. Any time I had one of those carbs on one of my engines I always removed the restricter jet and plugged the vacuum hose because it did exactly what baka says the OKO does, lean the mixture in the 1/4 to 1/2 throttle condition. The Dial-a-jet does just the opposite, it makes the mixture richer between 1/8 and 1/2 throttle settings.

[nacree]

The power jet on my OKO works just like a dial-a-jet. Vacuum from ahead of the trottle plate pulls in fuel via the power jet directly from the fuel bowl. I dont see how this would lean out the mid-range in any way.

-Nathan

[turtle13]

so would it be more apt to say that with these carbs you should disable the power jet. then tune, then re-able it and fine tune.
wiguy's theory is probably more accurate than most of us would want to admit.

[bakaracer]

the power jet itself doesnt lean out the engine,its the main jet your running to get the carb to run right leans it out. the jet inside for the power jet is the wrong size. thats why with it hooked up you will never get the CORRECT jetting setup. if you can find jets for that power jet then its possible to run the carb with the power jet hooked up.

[bakaracer]

I think what chew-baka is referring to is that most scooterists (myself included) are lazy and simply do a WOT plug to test for correct jetting. With the extra burst of fuel given at WOT from that power jet, the jetting can look spot-on but in reality it is incredibly lean in the mid range 1/4-3/4 throttle. This midrange is where most of our two-strokes spend their lives so burning a motor up is more likely.

its not being lazy. with 2 strokes if you dont do wot plug chops, your asking for trouble and for it to seize. if you set the main jet for the power jet to be hooked up,yes the midrange becomes lean and you will have huge flat spots in the throttle range. we just need to find different size jets for that power jet for it to run right with it hooked up.

[KingJeff801]

So is the safe bet to go with a 28mm on a 72cc even though its kind of overkill?