Why Disable OKO 24 Power Jet?

[Bear45-70]

Bear- I was simply expressing my way of looking at things. I told you I believe in empirical evidence more than anything (i.e. been there, done that). Your inferiority complex is your own issue. Waaay back several posts I agreed with you about the power jet not actively leaning out anything. I stand by the assertion that the power jet can mask a badly tuned mid range (i.e. very very lean).

So, if you have tuned a small displacement single cylinder air-cooled scooter with a CVT using a flatslide carb with a power jet I'm all ears. I understand the theory of how it should work but the devil is in the implementation. I have enjoyed the discussion up until the pejoratives went flying.

-Nathan

Two of them for than matter, after I installed Dial-a-jets in both my quads. So yeah, I know what I'm talking about besides that I was a factory certified 2 stroke mechanic for years with thousands of hours repairing the d*** things plus a was National Champion boat racer and record holder using 2 strokes, so yeah I know what I'm talking about. And don't be trying to tell me just because it is less than 100 cc that all the tuning rules go out the window. They don't because physics is a constant they all have to work under.

[nacree]

Bear,

We're not talking about dial-a-jets. I made that analogy but it was not correct. Dial-a-jets work across the entire rev range and therefore are good for across the board adjustment for situations like large ambient temperature changes and large elevation changes.

The power jet supposedly only starts working at 50% to WOT- allowing a smaller main jet for crisper throttle response. The power jet provides the fuel needed for large throttle openings and extended WOT.

http://www.thunderproducts.com/dial_a_jet.htm

Later,

Nathan

[Bear45-70]

If you are so fricking good, tune this.

[nacree]

I'm not an expert tuner, that's why I'm here asking questions.

Is that thing tuned for good response across the rev range or is that drag race oriented (i.e. WOT is the only concern)? Two completely different animals as I'm sure you're aware. Were there power jets on that?

I've never heard a six cylinder two stroke running- bet that thing sounded wicked.

[elitedio]

Bear
You have showed that photo a lot of times here. I have looked at the carbs each time and wonder.

Please start a new thread and describe your method of tuning a boat motor. Perhaps there is some cross over to 50cc scooters. BTW powerjets don't seem to work on them. Maybe you can be the first. I spent many houirs trying to get my scooter to run on it. Sometimes increased complication does not improve.

[808BMW]

Wow, looks like a lot of fun in here.

I'm sure there was always more to be had (I purposely jet rich because I ride far and want low temps) but I didn't have any extreme trouble tuning with or without my powerjet. I had a hole in my carb bowl in the PJ passage and needed to disable it (or spend money on parts, I chose the cheap option).

[Bear45-70]

Bear
You have showed that photo a lot of times here. I have looked at the carbs each time and wonder.

Please start a new thread and describe your method of tuning a boat motor. Perhaps there is some cross over to 50cc scooters. BTW powerjets don't seem to work on them. Maybe you can be the first. I spent many houirs trying to get my scooter to run on it. Sometimes increased complication does not improve.

If the power jet does not come on line until half throttle (I still can't figure out how they make it wait to start flowing fuel) then the needle needs to be raise or changed out all together to enrichen the fuel delivery below 1/2 throttle. Maybe just delete the needle all together. One of the things American 2 stroke manufactures did in the 1970's was build an intermediate fuel circuit into their carbs in addition to the idle and main jet circuits. Idle handles up to 1/8 throttle alone where the intermediate circuit comes on line then the intermediate and idle handle fuel flow to about 1/2 throttle where the main jet circuit starts flowing fuel. However to make sure that the main jet actually controls all fuel flow at 1/2 to WOT the idle and intermediate circuits pickup their fuel after the main jet. This way all fuel is metered thru the main jet. They dropped the needle stuff back in the dark ages of the 1950's because of lean conditions cause by them. I still don't understand why the Japanese are still using them for performance carbs, as the needle is not a performance item, it is a fuel economy deal. Today the only people in America claiming that needle carbs are performance carbs is Edelbrock and that's because he bought the rights to the old Carter carbs (that's 1950's technology) and it was all he could find to buy to try and compete with Holley.

[Wheelman-111]

Greetings:

Bear you are probably correct about the needle issue being more about fuel efficiency than high performance. I'd add the 70s ever-stricter ├®missions mandates, smoke and the general desire to "Civilize" 2-strokes. Toward those goals, the slide needle carbs do an admirable job, revealing their midrange shortcomings only in High-Po applications when the Main shuts down too soon due too soon due to too-thick needle, or too small a jet.

Oh-Eight, my goals are similar to yours. I am led to believe a 24mm will require smaller jets than the 30mm on the same setup. Considering starting with 58/155 and go down from there. Your Experience welcome. Anyone got a real skinny Keihin needle?.

[808BMW]

It's been quite a while, but I'm pretty sure my main jet is a 120/125 Pilot I'm unsure but it's around 50, maybe a 48 or 52. I really have to do a good tune-up on my bike, it's basically been "Set it, forget it, buy a plug every 2 months" for quite a while now (exactly how I like it, riding > wrenching).
I always wanted to get a 10-pack of needles to match my tuning set of pilot+main jets, but never got around to it.

[Wheelman-111]

Greetings:

Thanks 808BMW! So I take it the 24mm requires jetting to be a lot smaller than I'd use in a 28 or more? Forgive me, but with two cooked Ruimas in my sordid past, 125 sounds awfully small. If it smokes like Lindsay Lohan in Rehab and barely runs with a 155, I'll go down. One size at a time.

[bakaracer]

Again Bear the oko carb with the power jet the way it is cant be tunned right. the power jet is a fixed jet and is the wrong size. until someone finds different size jets for it, you cant get it to run right. Plan and simple.end of topic.

[Wheelman-111]

Greetings:

I understand the add-on Dial-A-Jet system is adjustable; Screwdriver and click to any of several positions? I take it the Power Jet on the OKO is not so adjustable, and the inserts are difficult to source?

[Bear45-70]

Again Bear the oko carb with the power jet the way it is cant be tunned right. the power jet is a fixed jet and is the wrong size. until someone finds different size jets for it, you cant get it to run right. Plan and simple.end of topic.

What you are saying is that you do not understand the Power jet and rather than make an effort to learn how it does work and learn a new tuning procedure, so you can tune it, you just disable it and blame the Power jet as bad. The bad part about this is that way to many people believe you rather than find out the truth. I find it totally inconceivable that OKO or any other carb manufacture would manufacture and market a carb that can't be tuned.

[wiguy05]

Again Bear the oko carb with the power jet the way it is cant be tunned right. the power jet is a fixed jet and is the wrong size. until someone finds different size jets for it, you cant get it to run right. Plan and simple.end of topic.

What you are saying is that you do not understand the Power jet and rather than make an effort to learn how it does work and learn a new tuning procedure, so you can tune it, you just disable it and blame the Power jet as bad. The bad part about this is that way to many people believe you rather than find out the truth. I find it totally inconceivable that OKO or any other carb manufacture would manufacture and market a carb that can't be tuned.

Bear, with all due respect, if you don't purchase an OKO carb and tune it yourself you have absolutely no room to talk. You sound just like a teenager threatening people with theories and other nonsensical garbage.



And no, you don't need to post the picture of the boat engine with 6 carbs "that you tuned 40 years ago". We have all seen it a thousand times.

[Wheelman-111]

Greetings:

Bear makes a good point. A feature isn't much use if it can't be tuned. Smart and dedicated as they are, few tuners evidently have had success getting it to work. The Power Jet is adding too much fuel on top. This suggests a solution could be to downsize the metering device. Evidently 808BMW is one exception. Did he get an OKO with a smaller-size PJ? It may be that the Power Jet "inserts" come in different sizes, and that they have become difficult to find. I plan to try my luck with Google.