Why Disable OKO 24 Power Jet?

[bakaracer]

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

you can use the 24mm oko just disable the power jet hose and jet the carb from there.

[Wheelman-111]

Greetings:

Thanks to all for this interesting discussion. Now see if I understand, Bakaracer:

1. The PowerJet adds some mixture at high throttle openings.
2. As sized, the "jet" in the PJ system adds so much that it over-richens the WOT mixture.
3. This means the Main Jet must be downsized so much that the engine starves in the midrange.

SO do I understand correctly? If so, a couple follow-up questions:

1. Where is the "jet" or rate-controlling device in the PJ system, and does it come in different sizes?
2. Is it possible to compensate with a stupid-big Pilot, and/or perhaps with a raised needle?

Or is the whole thing too "Gimmicky" and best eliminated? (OK that was three questions... )
Here's another. Why do you suppose Keihin/OKO bothered to develop the system, but then limited its availability only to the 24mm carb? If it's a good idea for one size, you'd think they'd apply it to others.

[bakaracer]

oko does have the power jet on other size carbs. the jet is inside of that screw on top of the mouth of the carb. I had issues of tryingg to tune the carb with the power jet hooked up and I didn't have needles to play with to try and see if I could get it right. i have lots of needles now but haven't had time to see if I could tune the carb with the power jet hooked up.if there was a smaller jet size for the power jet,im sure it would help. it just feeds to much gas once you get to about 3/4 throttle or just before it. thats when gas startes to flow up the tube to the mouth of the carb. if you try to do it with the bike on the stand,it wont do it. you have to be riding under load.for all you newbies to tunning carbs like this.

[Bear45-70]

OK, I'm still having a problem here with this supposed leaning out in the mid-range stuff. Basically HOW? If this power jet works just like the Dial-a-jet, once it comes on line and starts flowing fuel, it stays on line until the air flow thru the carb drops below the level required to pull fuel thru it. So at any throttle setting it still flows fuel so a smaller main jet to compensate for the power jet's fuel flow can't make anything go lean unless the power jet quits flowing fuel which it should not.

[nacree]

OK, I'm still having a problem here with this supposed leaning out in the mid-range stuff. Basically HOW? If this power jet works just like the Dial-a-jet, once it comes on line and starts flowing fuel, it stays on line until the air flow thru the carb drops below the level required to pull fuel thru it. So at any throttle setting it still flows fuel so a smaller main jet to compensate for the power jet's fuel flow can't make anything go lean unless the power jet quits flowing fuel which it should not.

I think I understand what Baka is saying- it does not actually lean the midrange- it just masks a badly tuned midrange because the power jet helps the midrange to WOT bog you might normally have if the Mid was lean and the carb had no power jet.

-Nathan

[Bear45-70]

OK, I'm still having a problem here with this supposed leaning out in the mid-range stuff. Basically HOW? If this power jet works just like the Dial-a-jet, once it comes on line and starts flowing fuel, it stays on line until the air flow thru the carb drops below the level required to pull fuel thru it. So at any throttle setting it still flows fuel so a smaller main jet to compensate for the power jet's fuel flow can't make anything go lean unless the power jet quits flowing fuel which it should not.

I think I understand what Baka is saying- it does not actually lean the midrange- it just masks a badly tuned midrange because the power jet helps the midrange to WOT bog you might normally have if the Mid was lean and the carb had no power jet.

-Nathan

Well, I don't understand you at all because your statement makes no sense what so ever. The power jet comes on line and flows fuel SOONER than the main fuel circuit does and that is how it prevents the bog, but if the main is only as much smaller is size as the power jet ability to flow fuel, it can't lean out anything. The only way it could cause a lean condition is if the main was to small and that is the tuners fault, not the power jet's.

[nacree]

OK, I'm still having a problem here with this supposed leaning out in the mid-range stuff. Basically HOW? If this power jet works just like the Dial-a-jet, once it comes on line and starts flowing fuel, it stays on line until the air flow thru the carb drops below the level required to pull fuel thru it. So at any throttle setting it still flows fuel so a smaller main jet to compensate for the power jet's fuel flow can't make anything go lean unless the power jet quits flowing fuel which it should not.

Bear that is what I am saying- it does not actively lean anything. It can mask a lean midrange (wrong needle taper etc.) or a badly sized main jet.

-Nathan

[Bear45-70]

Bear that is what I am saying- it does not actively lean anything. It can mask a lean midrange (wrong needle taper etc.) or a badly sized main jet.

-Nathan

No, it can't mask anything and the needle will be less effective in it's ability to restrict fuel flow (lean out the engine) in the mid range because it can do nothing to the dial-a-jet or power jet fuel flow. So the mid range would be RICHER not leaner. The only way you can end up lean is to have to small of a main and that would only be at WOT. All that the power jet does is act as another outlet for fuel like the main jet does, only the needle CAN NOT restrict it's flow. Both the carbs on my quads are slide carbs, with needles and the only thing the Dial-a-jet did was start flowing fuel sooner than the main jet circuit, because like I said the needle can not restrict it.

[nacree]

Bear that is what I am saying- it does not actively lean anything. It can mask a lean midrange (wrong needle taper etc.) or a badly sized main jet.

-Nathan

No, it can't mask anything and the needle will be less effective in it's ability to restrict fuel flow (lean out the engine) in the mid range because it can do nothing to the dial-a-jet or power jet fuel flow. So the mid range would be RICHER not leaner. The only way you can end up lean is to have to small of a main and that would only be at WOT. All that the power jet does is act as another outlet for fuel like the main jet does, only the needle CAN NOT restrict it's flow. Both the carbs on my quads are slide carbs, with needles and the only thing the Dial-a-jet did was start flowing fuel sooner than the main jet circuit, because like I said the needle can not restrict it.

Bear,

Were saying the same thing- I am apparently having trouble getting my thoughts across. Suffice it to say I agree.

[bakaracer]

Bear how about you go and tune the oko power jet and then come back and tell us how it goes. There have been ALOT of guys for the past 15 years that have tried and couldn't get the carb to work with the power jet hooked up. again the jet in the power jet IS THE WRONG SIZE.

[Trafficjamz]

Bear how about you go and tune the oko power jet and then come back and tell us how it goes. There have been ALOT of guys for the past 15 years that have tried and couldn't get the carb to work with the power jet hooked up. again the jet in the power jet IS THE WRONG SIZE.

When disabling the power jet on the oko carb , do you:

a)just remove the tube

b)remove the tube and plug the carb nipples.

[Bear45-70]

Bear how about you go and tune the oko power jet and then come back and tell us how it goes. There have been ALOT of guys for the past 15 years that have tried and couldn't get the carb to work with the power jet hooked up. again the jet in the power jet IS THE WRONG SIZE.

If it engine does go lean in the mid range, then what your claim that it works like the Dial-a-jet is false. It is irrelevant what size the jet is in the power jet, once it starts flowing fuel it will flow that fuel until the air flow drops to low to suck the fuel. The power jet's jet is not too small the main jet is too small because the power jet will be constant in its flow, otherwise the more the engine sucks the more fuel it will flow. But the needle will not change that so the main jet circuit is the problem because it's and only it's fuel flow can be screwed with by the needle. If the carb is going lean, blame the main fuel circuit and not the power jet because the power jet will flow what it flows and it can not alter that. d***, am I the only one here that actually understands carbs and how they work and how fuel flows thru them? If the engine is leaning out it is because of either the main jet is too small or the needle is to big or both, but it is not a power jet problem it is the main fuel circuit in the carb's problem. There is no way on this planet with our physic's laws in place that the power jet will suddenly flow less fuel in the mid range, it is just not possible regardless of the nozzle size.

[elitedio]

my 86 has a 28 OKO with a power jet.

I don't like it if only because it is another jet to buy and tune. I tried opening it up a bit and that made it worse.

I ended up putting a bb in the tube that goes up to the power jet. Just set the mj so that it runs on top and leave it alone. If It seems a bit rich at times I back the throttle down till it matches.

I have a 21 oko on my zuma 49. With out a pj. I have noticed that the mixture seems to be a bit rich at 3/4ths then at high rpm after the variator has topped out, it starts to match a bit better.

Bear, as you know it is more than just the throttle position. It is the throttle position and the rpm. As the engine comes on the pipe it goes leaner and wants a bit more gas. I've had engines that will barely pull on the pipe then once they catch they keep getting stronger I've leaned the MJET down and it pulls better at first but once it is going it doesn't get as strong.

Wheelman I think there is potential with the power jet but it complexes me out.

[bakaracer]

Bear how about you go and tune the oko power jet and then come back and tell us how it goes. There have been ALOT of guys for the past 15 years that have tried and couldn't get the carb to work with the power jet hooked up. again the jet in the power jet IS THE WRONG SIZE.

If it engine does go lean in the mid range, then what your claim that it works like the Dial-a-jet is false. It is irrelevant what size the jet is in the power jet, once it starts flowing fuel it will flow that fuel until the air flow drops to low to suck the fuel. The power jet's jet is not too small the main jet is too small because the power jet will be constant in its flow, otherwise the more the engine sucks the more fuel it will flow. But the needle will not change that so the main jet circuit is the problem because it's and only it's fuel flow can be screwed with by the needle. If the carb is going lean, blame the main fuel circuit and not the power jet because the power jet will flow what it flows and it can not alter that. d***, am I the only one here that actually understands carbs and how they work and how fuel flows thru them? If the engine is leaning out it is because of either the main jet is too small or the needle is to big or both, but it is not a power jet problem it is the main fuel circuit in the carb's problem. There is no way on this planet with our physic's laws in place that the power jet will suddenly flow less fuel in the mid range, it is just not possible regardless of the nozzle size.

again you try and tune one and get back to us. until then the power jet doesn't work good on our motors with the stuff we are using.

[808BMW]

When disabling the power jet on the oko carb , do you:

a)just remove the tube

b)remove the tube and plug the carb nipples.

I took off the carb bowl, cleaned it out, and then used JB weld to fill the passage going to the power jet.