NEW KEIHIN REPLICA PWK 30mm FLATSLIDE CARBY

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deon.jacob

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Any body tried these carbis and know if they are any good? Can someone also tell me if it will bolt onto pitpro 138cc and make much difference?


eBay Australia: NEW KEIHIN REPLICA PWK 30mm FLATSLIDE CARBY CRF PITBIKE (item 230121457079, end time 29-Apr-07 20:15:00 AEST)
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Hey there, the port on my lifan 120cc is 28mm wide, so a 30mm carb would be waste..the oko carbs that dhz sell are great carbs..however their not flatside..but d slide..which is slightly harder to tune. You won't be able to find a manifold that's 30mm wide either..so it's pretty waste..for a standard 138cc (127cc) i would think that the 24mm carb from dhz would be great..or a 26mm good too..keep in mind the carb you have now is most likely around 22mm..cause of the oval venturi (if it's a mikuni copy)
 
The carby is not the issue its getting a mounting system that will allow it to fit and still be a decent size. Most manifolds for them are only 26mm at the most and more often much smaller. On a stock bike under 140cc I would say over carbed with that baby unless you planned tuning it for methanol?????
 
Le|Garage said:
Hey there, the port on my lifan 120cc is 28mm wide, so a 30mm carb would be waste..the oko carbs that dhz sell are great carbs..however their not flatside..but d slide..which is slightly harder to tune. You won't be able to find a manifold that's 30mm wide either..so it's pretty waste..for a standard 138cc (127cc) i would think that the 24mm carb from dhz would be great..or a 26mm good too..keep in mind the carb you have now is most likely around 22mm..cause of the oval venturi (if it's a mikuni copy)
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Whered you get that 60.5 mm stroker crank?
I wanna add it to my tb 146 set up with big valve and cam. RIP.
 
deon.jacob said:
Any body tried these carbis and know if they are any good? Can someone also tell me if it will bolt onto pitpro 138cc and make much difference?


eBay Australia: NEW KEIHIN REPLICA PWK 30mm FLATSLIDE CARBY CRF PITBIKE (item 230121457079, end time 29-Apr-07 20:15:00 AEST)
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You'd be better off buying the 24 mm OKO kit he sells if you want snappy throttle response - it comes with a manifold and rubber adaptor , air filter and throttle cable ! The actual valve throat on the Big valve heads is only around 23 mm - then there's the thickness of the 4 mm valve stem which also reduces the throat area so a 24 to 26 mm carb would be more than adequate for dirt riding - especially since your "138" engine is really only 127 cc !

If you contact DHZ direct , he'll give you a better price than on ebay - he's prompt and reliable and sends by courier - usually the same day you pay if it's not too late ! I just bought a 28 OKO kit off him for a ported and cammed 140 but I haven't tried it yet ! I didn't like the short air filters with the blank metal at the end supplied with the kits , so I bought mine without one and then I found that UNI doesn't make foam pods to fit OKO's !

Incidentally - he says he'll have bigger 30 mm I/D manifolds soon ! The kits come with 26 mm I/D manifolds which can be easily taken to 28 mm safely .
 
I'm keen to find out what the 28 and 30mm carbs are like. I've heard the Keihin's are great, but haven't any experience myself. The 26mm Mikuni goes pretty well when jetted right, but I like the idea of a flat slide carb.

I'm sure one of the top motard guys runs a 24mm Keihin flat slide because he thinks any more is wasted. I'd say on a full ported, cammed with big valves, exhaust and manifold, 28mm would work well. 30mm on a 125 or 140 just seems too big a jump, but I could be wrong.
 
People are deceived into thinking you can easily run a true 28 and 30mm carb on these engines because of the mikuni carbs advertised at these sizes by the ebay sellers. Have a look down the throat of your (so called) 30mm mikuni carb and if you have access to one have a look down a 28mm round bore or flatslide/d-slide carb. Those 28mm OKO carbs are a heck of a lot bigger than the advertised 30mm mikuni's. I think, by memory, those (so called) 30's are only really 22mm at the slide! You really want to be looking at building a bigger engine with head upgrades to get best use from a 28mm OKO.
 
Mack said:
People are deceived into thinking you can easily run a true 28 and 30mm carb on these engines because of the mikuni carbs advertised at these sizes by the ebay sellers. Have a look down the throat of your (so called) 30mm mikuni carb and if you have access to one have a look down a 28mm round bore or flatslide/d-slide carb. Those 28mm OKO carbs are a heck of a lot bigger than the advertised 30mm mikuni's. I think, by memory, those (so called) 30's are only really 22mm at the slide! You really want to be looking at building a bigger engine with head upgrades to get best use from a 28mm OKO.
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The "30" mm Mikuni carbs only LIFT the slide 30 mm high . They are a 30 mm x 22 mm oval BORE thru the slide / choke area . They're made like that in an attempt to maintain air velocity for better off idle and bottom end throttle response . A 28 mm OKO is 28 mm round all the way thru so the velocity drops quicker as the slide is lifted .

A lot of people think they can fit a big carb and still twist the throttle as quick as they can with a smaller stock carb - well they are in for a big shock because they'll have to learn to ride with controlled throttle restraint ! Most people will make a 4 stroke engine bog with a big carb so they're best sticking to a smaller carb . Either that or fit a slow turn throttle or a cammed throttle .

The bog can't be tuned out either - because it's caused by a sudden vacuum drop when the larger slide is lifted too quickly . Carbs rely on vacuum to pull fuel thru the jets - a vacuum drop means the fuel delivery also drops - at a time when you want it to increase . The ONLY fix is to fit a carb with an accelerator pump or slow your right hand down .

I suggested people use a 24 - 26 OKO because the 28's will most likely be touchy and require careful throttle control to make them work . I would have preferred a smaller carb myself but that's all he had - there's NO way I'd have bought a 30 mm OKO .
 
What size and tune engine are you running, Cactus Jack? Have you got a cam and port to suit the 28? I presume you have the 28?

My situation is I have a 125RR Motard which I need good midrange and top end on. I won't go bigger than 26 until I get a full race cam, exhaust and intake port to suit.
 
Cactus Jack said:
A lot of people think they can fit a big carb and still twist the throttle as quick as they can with a smaller stock carb - well they are in for a big shock because they'll have to learn to ride with controlled throttle restraint ! Most people will make a 4 stroke engine bog with a big carb so they're best sticking to a smaller carb . Either that or fit a slow turn throttle or a cammed throttle .
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Yes the quick turn throttles make the problem far worse. I have never liked the quick turn throttles and always use the stock throttles. Makes for much better control over the power delivery. You can still slam it open, its not hard to do with a stock throttle! Most of the stock throttles are just sloppy and can't be adjusted out using the cable adjusters. You have to redrill the hole for the cable end in the throttle body about 5mm further round and extend the slot. 5 min job. Then a little lube in the throttle body and cable. They then can be adjusted correctly at the throttle to have zero slack and become very responsive and light.

Ausjames IMO you would be best using a 24mm carb with a 125cc engine in light tune, 26mm with a full race 125cc using standard size valves and 28mm if you go up in valve size and seriously port and flow the head, although you could still run the 26mm very succesfully, or even make it perform better than a 28 with carb porting.
 
Taht's pretty much what I thought. I've really only seen the OKO Keihin knock offs in 28 and 30's, and I thnk I've seen a 24 too. do they make a 26 flatslide?

I'm pretty happy with my 26 with free flowing filter and open exhaust. after some jetting work, it's a fair bit better, but I'm always after that bit more :)
 
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Go big and get a FCR 39mm..... i've seen a few engines running these but i would say they are highly tuned..
 
well ..between an FCR Keihin and this shitty china okomikuniwhatevercrap is a lot more to get ...like the good old original KeihinPE 24 or MikuniVM26....don´t waist your money on this other ones;)
 
themountain said:
well ..between an FCR Keihin and this shitty china okomikuniwhatevercrap is a lot more to get ...like the good old original KeihinPE 24 or MikuniVM26....don´t waist your money on this other ones;)
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Both great carbs - IF you can get them for the right price without getting ripped off ................
 
mack

mack do you sell lifans on ebay?? also do you think a 24 mm oko d slide carb will go good with a 140cc lifan stock?? i dont want to lose top end as i ride on race track so?..:D p.s any hints on what ratio to run on my bike as i have a stock 140cc lifan, like what front sprocket, rear sprocket, carb size and jets and air filter to use i know thats a big ask but ive been searching this forum to no end and cant find any answers. id love one of those fcr 28" carbs as i think it would be more suited to racing on track thatn dirt? but one thing has got me stumped why isnt there an air filter on them things? wont dirt get in??
 
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