yx 196cc, OKO 28mm..which needle????
- Thread starter sean01
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sean01
Legend Spanner Spinner
fair enough but you could at least make it a little easier for us to read...
sean01
Legend Spanner Spinner
lol, yeah im lost too...either way he has mucked it up....throw in the bin and start again
sean01
Legend Spanner Spinner
looks like im gonna have try both the JJH and JJG needles and see which is better..
sean you mentioned you have a 28mm OKO flatslide, but it's running Mikuni styel round main jet...
Dont sound right... OKO flatslides are meant to run Keihin style mains and pilots... ie: shortish Hexagonal head mains... not round flathead style mains...
If for some reason your flatslide is running a mikuni style main, might wanna change it to a proper style jets....
can you post pics of the jets you have?
If you are running mikuni style jets, it may be contributing to the problem, but i'm having the same problem tuning the hesitation out of my 28mm on the 140... as you said, you can shift the hesitation, but cant get rid of it altogether
Dont sound right... OKO flatslides are meant to run Keihin style mains and pilots... ie: shortish Hexagonal head mains... not round flathead style mains...
If for some reason your flatslide is running a mikuni style main, might wanna change it to a proper style jets....
can you post pics of the jets you have?
If you are running mikuni style jets, it may be contributing to the problem, but i'm having the same problem tuning the hesitation out of my 28mm on the 140... as you said, you can shift the hesitation, but cant get rid of it altogether
sean01
Legend Spanner Spinner
the carb i have came standard with keihin round jets...mikuni jets have different thread...
im not sure if the bowl will allow a hex jet to be fitted...
what needle are you running because i think this is where the problem lays...wrong tapper on the needle...
im going to get a JJH needle and try it so i may as well try a hex jet too....
but just remember you can actually remove the mainjet all together and still ride the bike, and yes the hesitation will still be in the same spot..
i have also heard of ppl drilling the mixture screw circuit larger...to like 2mm or sumthin
im not sure if the bowl will allow a hex jet to be fitted...
what needle are you running because i think this is where the problem lays...wrong tapper on the needle...
im going to get a JJH needle and try it so i may as well try a hex jet too....
but just remember you can actually remove the mainjet all together and still ride the bike, and yes the hesitation will still be in the same spot..
i have also heard of ppl drilling the mixture screw circuit larger...to like 2mm or sumthin
woods11
Active Member
Have you blocked the brass inlet that is on top of the intake side of the carby? The keihin/oko 28mm carbs should be using the large hex keihin main jet.
sean01
Legend Spanner Spinner
which brass inlet are you referring to....
and and the jet type isnt my problem, i will try and change them but again it isnt my problem...
mainjet doesnt affect off idle throttle
woods11
Active Member
There should be a brass inlet which looks like an overflow which sticks out from the top of the motor side of the carby. It sucks extra air in and makes it impossible to jet.
sean01
Legend Spanner Spinner
nah that aint on mine...
i just come across a pic of what your talking about...i definitely dont have that brass vacuum fitting on mine...
i just come across a pic of what your talking about...i definitely dont have that brass vacuum fitting on mine...
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Sean01 can you post a pic up of yours, with the float bowl off? sounds like you have somthing vastly different to what me and a few other boys have... mine also has the extra brass inlet next to the choke, which i have blocked off on mine... and as f****d up as this sounds, the main jet with the OKO flatslides, for some God Unknown reason will effect response off idle... when the main jet is too big, the response off idle is very sharp... but clearly, it wont work on WOT... get the main jet right, and response off idle is pretty bad, with a bit of a bog/hesitation that is damn near impossible to get rid of....
woods11
Active Member
Thumps right. Main jet will affect the low end on these carbs.
Your jetting sounds way to rich if you compare it to what other people are running.
Your jetting sounds way to rich if you compare it to what other people are running.
sean01
Legend Spanner Spinner
youll have to wait for a pic, the carb isnt here with me its on the bike at my mates workshop.
anyways, when i got the carb (approx 18months-2 yrs ago) it was off a guy on ebay(before the OKO's were around anywhere) he claimed he used the exact carb on his 187cc stroker yx140.(im pretty sure the dude is on this forum) oh and it didnt come in an OKO box.
anyways i asked about the mainjet and he said that its the style that that carb uses, he also said it shouldnt matter about the main jet style...
i wasnt happy with the carb from day dot.....non-chromed slide, choke that wouldnt work and the knob would come off, wrong needle and needle jet, rubber top gasket for the slide cover which stretch's when over tightened and yes this sus mainjet...
im thinkin he robbed the hex mainjet out of it and replaced it with a china jet...it was a no name jet, it went in the bin same as the pilot....
also while i been reading the last couple of posts it occured to me that if the mainjet was too short then the needle may poke out the jet allowing for it to do something weird to the emulsion tube.
ok well im gona try a JJH needle and a hex mainjet....
i have tried a 112 and a 120 main and going from 3/4 to full throttle it would just be dead(the 120 was better) anyways 138(i think) is in it now and it pulls all the way with no top end bog..
but yeah the low end makes the bike unridable on a track as when you need to use the throttle for jumps your either gona flip it or endo it...
lolz...now if that doesnt fix it then its going in the bin and ill get a genuine pwk 28 off a kx or yz 85
anyways, when i got the carb (approx 18months-2 yrs ago) it was off a guy on ebay(before the OKO's were around anywhere) he claimed he used the exact carb on his 187cc stroker yx140.(im pretty sure the dude is on this forum) oh and it didnt come in an OKO box.
anyways i asked about the mainjet and he said that its the style that that carb uses, he also said it shouldnt matter about the main jet style...
i wasnt happy with the carb from day dot.....non-chromed slide, choke that wouldnt work and the knob would come off, wrong needle and needle jet, rubber top gasket for the slide cover which stretch's when over tightened and yes this sus mainjet...
im thinkin he robbed the hex mainjet out of it and replaced it with a china jet...it was a no name jet, it went in the bin same as the pilot....
also while i been reading the last couple of posts it occured to me that if the mainjet was too short then the needle may poke out the jet allowing for it to do something weird to the emulsion tube.
ok well im gona try a JJH needle and a hex mainjet....
i have tried a 112 and a 120 main and going from 3/4 to full throttle it would just be dead(the 120 was better) anyways 138(i think) is in it now and it pulls all the way with no top end bog..
but yeah the low end makes the bike unridable on a track as when you need to use the throttle for jumps your either gona flip it or endo it...
lolz...now if that doesnt fix it then its going in the bin and ill get a genuine pwk 28 off a kx or yz 85
sean01
Legend Spanner Spinner
who has a 196cc to compare against?
might add to the above post to that the guy i got the carb off was running a 138 in his 187cc
lol i could keep adding to this all day with what i have tried....
the hestitation down low didnt change with raising or lowering the mainjets
woods11
Active Member
I had the oko 28mm on my previous 184cc motor as well and the jetting was still 110 main and 42 pilot with stock needle one up from the bottom. I would say change to a hex main or go with a genuine PWK.
sean01
Legend Spanner Spinner
cheers for that info....lol i been waiting for someone with a similar setup to comment.
yeah ill try the needle and hex jet and see how it goes...
also what needle were you running...
and does anyone know what needles come standard in the DHZ OKO's? think i might hit him up for one if there the correct ones, the kwaka shop near doesnt have any needles..
yeah ill try the needle and hex jet and see how it goes...
also what needle were you running...
and does anyone know what needles come standard in the DHZ OKO's? think i might hit him up for one if there the correct ones, the kwaka shop near doesnt have any needles..
just had two thoughts on this one... the shorter "mikuni" style main jet is a lot shorter than the hex style main jet... which would vastly effect the point at which the needle jet is starting to "pull up" out of the main... in other words, it's not working properly, at the correct point/taper ogive on the needle, and would thus be bending your jetting over, and doing it sans-lube... theres a good 3-4mm difference in jet height, so i reckon it wouldnt be working at all properly, and no matter where you move the clip on the needle, it would still be all wrong, as with the hex jet at say half throttle, the needle is where it should be... still in the main jet hole... with the mikuni main, at half throttle it *may* well be clear of the main jet, and dumping waaaayyy too much fuel through... hence the $hittiness at half throttle onwards...
The other thing to consider, is that the emulsion tube on the pilot and main for the genuine PWK carbies from the TWO STROKE 85 carbies, i believe are quite different... Four stroke pilot and main emulsion tubes have a lot more holes in them, if memory serves to aid in fuel velocity, as in a two stroke engine, the fuel is travelling up the main and pilot jet a lot quicker...
i may be entirely wrong on that one, it's something i read a loooooong time ago, but cactus may be able to shed some light on it...
We really need some sort of early warning system for Cactus help... or a BatLight... does anyone have a flare pistol??? SEND UP A VEREY LIGHT!!!!!
i'm still a bit sus on your actual main jet size... obviously, you have it working ok at present, but a 138 main is huge for a little motor... yes, it's big blocked, but a 197cc horizontal motor is still tiny... My 750 V-twin in the Black Widow, runs #132 mains as standard.. twin carbys, and are 375cc per pot...
Not sure mate, i think it may be time to turf the 28mm you have, and update....
The other thing to consider, is that the emulsion tube on the pilot and main for the genuine PWK carbies from the TWO STROKE 85 carbies, i believe are quite different... Four stroke pilot and main emulsion tubes have a lot more holes in them, if memory serves to aid in fuel velocity, as in a two stroke engine, the fuel is travelling up the main and pilot jet a lot quicker...
i may be entirely wrong on that one, it's something i read a loooooong time ago, but cactus may be able to shed some light on it...
We really need some sort of early warning system for Cactus help... or a BatLight... does anyone have a flare pistol??? SEND UP A VEREY LIGHT!!!!!
i'm still a bit sus on your actual main jet size... obviously, you have it working ok at present, but a 138 main is huge for a little motor... yes, it's big blocked, but a 197cc horizontal motor is still tiny... My 750 V-twin in the Black Widow, runs #132 mains as standard.. twin carbys, and are 375cc per pot...
Not sure mate, i think it may be time to turf the 28mm you have, and update....
woods11
Active Member
I am using the JJH which comes stock in the carbs that DHZ sells.
sean01
Legend Spanner Spinner
just had two thoughts on this one... the shorter "mikuni" style main jet is a lot shorter than the hex style main jet... which would vastly effect the point at which the needle jet is starting to "pull up" out of the main... in other words, it's not working properly, at the correct point/taper ogive on the needle, and would thus be bending your jetting over, and doing it sans-lube... theres a good 3-4mm difference in jet height, so i reckon it wouldnt be working at all properly, and no matter where you move the clip on the needle, it would still be all wrong, as with the hex jet at say half throttle, the needle is where it should be... still in the main jet hole... with the mikuni main, at half throttle it *may* well be clear of the main jet, and dumping waaaayyy too much fuel through... hence the $hittiness at half throttle onwards...
The other thing to consider, is that the emulsion tube on the pilot and main for the genuine PWK carbies from the TWO STROKE 85 carbies, i believe are quite different... Four stroke pilot and main emulsion tubes have a lot more holes in them, if memory serves to aid in fuel velocity, as in a two stroke engine, the fuel is travelling up the main and pilot jet a lot quicker...
i may be entirely wrong on that one, it's something i read a loooooong time ago, but cactus may be able to shed some light on it...
We really need some sort of early warning system for Cactus help... or a BatLight... does anyone have a flare pistol??? SEND UP A VEREY LIGHT!!!!!
i'm still a bit sus on your actual main jet size... obviously, you have it working ok at present, but a 138 main is huge for a little motor... yes, it's big blocked, but a 197cc horizontal motor is still tiny... My 750 V-twin in the Black Widow, runs #132 mains as standard.. twin carbys, and are 375cc per pot...
Not sure mate, i think it may be time to turf the 28mm you have, and update....
lol, yeah thats the long version of what i was thinking...oh and also the main jets im using now are keihin jets not mikuni...yeah i know they still short, i thought id just say something in chase you were actually thinkin i was using mikuni...
man i wish i could remember who i bought the carb off....
cheers guys for all your info and thoughts
