28mm carb fitment help

fxchris

New Member
Oct 20, 2010
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Miami, Fl
so i got my carb yesterday and it wouldnt wanna fit in the air box tube nor would it go in snug on the reed vavle side either . i dont think they sent me the 28mm i think its a 30mm or bigger . is there any way to tell ?
 
keihin's say on the side, PWK and a string of numbers.

You can also measure the throat diameter and see which one it is, but I can tell you that the PWK28 is a tight fit in the factory intake boot and the airbox boot has to modified to fit one in.

Most people cut the airbox boot back about 4 inches, get a piece of pipe with the same OD as the upstream side of the carb and then a rubber connector and a few clamps. I went ahead and built a new airbox with a pod style filter in it.
 
keihin's say on the side, PWK and a string of numbers.

You can also measure the throat diameter and see which one it is, but I can tell you that the PWK28 is a tight fit in the factory intake boot and the airbox boot has to modified to fit one in.

Most people cut the airbox boot back about 4 inches, get a piece of pipe with the same OD as the upstream side of the carb and then a rubber connector and a few clamps. I went ahead and built a new airbox with a pod style filter in it.

sooo a 28mm carb is not perfect fit for direct bolt on ? i thought it was . it goes in to the intake side but not completley snug it hits the clutch leveler a lil .
 
sooo a 28mm carb is not perfect fit for direct bolt on ? i thought it was . it goes in to the intake side but not completley snug it hits the clutch leveler a lil .

well aint that a biotch.. if its hitting the clutch lever you can either tilt the carb a little or get a reed spacer. just do what civic said for the airbox side, its real easy and pretty cheap to get the stuff from lowes. if you want a reed spacer LMK i have one sitting here i would give ya for super cheap.
 
well aint that a biotch.. if its hitting the clutch lever you can either tilt the carb a little or get a reed spacer. just do what civic said for the airbox side, its real easy and pretty cheap to get the stuff from lowes. if you want a reed spacer LMK i have one sitting here i would give ya for super cheap.

yess it really is a biotch lmao i was dying to ride until i ran into this lol and yeaa i do want the reed spacer . pm me the price . and what do i need from lowes to do it ?
 
It's not a perfect fit but it's not too bad though. It's not a bad compromise for the performance you stand to gain by having it there. UPP sells an aftermarket intake manifold if the squeezing really bothers you but it won't hurt anything as long as the clamp tightens down satisfactorily.

You can rotate it a little bit to get it away from the clutch lever. Or adjust your clutch a little farther in to keep it away.


The air intake boot is the real fitment issue here. The stock 26mm Mikuni only has like an inch and a half airhorn where as the PWK has a 2" airhorn but only a 2mm larger throat.

There are pictures floating around of people who bought a piece of 2" OD pipe and a 2" ID sanitary rubber coupler (crapper pipe coupler) You have to cut the air intake back about 3-4" (where the ID of the factory rubber is about 2" and then shove the new pipe inside the old rubber tube and clamp it there. Then trim the rubber down to where it mates between the tube and carb airhorn and clamp both ends. 2 out of 10 in difficulty.
 
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yess it really is a biotch lmao i was dying to ride until i ran into this lol and yeaa i do want the reed spacer . pm me the price . and what do i need from lowes to do it ?

just find a good spot to cut the airbox boot a few inches back from the carb where the opening would be bigger then get a piece of pvc that will fit in there and some hose clamps. then for the carb side take the carb with you and get the correct rubber boot that will connect the carb to the piece of pvc coming out of the airbox. super easy man for around $10 and 15 mins
 
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just find a good spot to cut the airbox boot a few inches back from the carb where the opening would be bigger then get a piece of pvc that will fit in there and some hose clamps. then for the carb side take the carb with you and get the correct rubber boot that will connect the carb to the piece of pvc coming out of the airbox. super easy man for around $10 and 15 mins

alright gotcha il go do that today . and how can i tell if my carb is the 28mm ? i just wanna make sure
 
What are the numbers and letters? It's a serial number code. Keihin makes about 50 different options for the PWK series. Power jet, diverter, slide shape, even the cable outlet. The code on the side should tell you exactly what you bought.
 
What are the numbers and letters? It's a serial number code. Keihin makes about 50 different options for the PWK series. Power jet, diverter, slide shape, even the cable outlet. The code on the side should tell you exactly what you bought.

the code is just like that this . G617 AAE7
 
A G617 looks up to a 28mm the AAE7 doesn't jive but that doesn't really mean anything.

I'd guess you have an unserial numbered keihin 28mm carburetor. That either means it's a knock-off or wasn't "factory tuned".
 
A G617 looks up to a 28mm the AAE7 doesn't jive but that doesn't really mean anything.

I'd guess you have an unserial numbered keihin 28mm carburetor. That either means it's a knock-off or wasn't "factory tuned".

yea its a 28mm i called project blaster cuz thats where i ordered it from and they said it was a 28mm n that i could stretch out the air tube with a heat gun to fit the carb .
 
Ok, so that just means it wasn't "factory tuned" which is fine. Even the factory tuned models have to be jetted to your particular configuration anyway....

Good luck with that... I tried it with a heat shrink gun (about 350 deg F) and a tailpipe expander. Two days I fiddled with it before I finally started making a new airbox... The best bet is to get a short piece of 2" OD pipe and a rubber coupler. Makes life a LOT simpler.
 
To the best of my knowledge, Keihin doesn't make a 30mm anyway, for the aftermarket. OKO does tho, but they clearly say OKO on them. PB is not going to sell you a knockoff. The 28mm is easy to ID because it is the only one that has screws holding on the carb cap.

I found that the carb slips into the stock intake boot fine, but only if I backed out the clamp all the way. It's funny cuz up to that point it seems like it should go in, but it is hard to get past the ridge inside the boot until the clamp is way looser than you think it should need to be.

Turning the carb just enough to clear the clutch lever works fine after triming off the little rubber nubs on the boot, but if Noob wants to sell a spacer cheap then go for it. (looks cleaner)

On the airbox side, I used a coupler from the plumbing department that is used to clamp together iron or ABS drain pipe, 2in sounds about right but just take the carb with you and see what fits best. It is cool because it includes the clamps and a shiny steel cover, with the clamps being permanently attached (very handy). For the tube part, I used a 6in long piece of steel EMT conduit, it's strong and thin, and cut the airbox tube off where it started to bell out, just where the EMT fit snuggly inside. Total spent? Less than 10 bucks.

Never tried the stretch thing, but obviously you would need more heat than civic used. Maybe a heat gun for paint removal.
 
To the best of my knowledge, Keihin doesn't make a 30mm anyway, for the aftermarket. OKO does tho, but they clearly say OKO on them. PB is not going to sell you a knockoff. The 28mm is easy to ID because it is the only one that has screws holding on the carb cap.

I found that the carb slips into the stock intake boot fine, but only if I backed out the clamp all the way. It's funny cuz up to that point it seems like it should go in, but it is hard to get past the ridge inside the boot until the clamp is way looser than you think it should need to be.

Turning the carb just enough to clear the clutch lever works fine after triming off the little rubber nubs on the boot, but if Noob wants to sell a spacer cheap then go for it. (looks cleaner)

On the airbox side, I used a coupler from the plumbing department that is used to clamp together iron or ABS drain pipe, 2in sounds about right but just take the carb with you and see what fits best. It is cool because it includes the clamps and a shiny steel cover, with the clamps being permanently attached (very handy). For the tube part, I used a 6in long piece of steel EMT conduit, it's strong and thin, and cut the airbox tube off where it started to bell out, just where the EMT fit snuggly inside. Total spent? Less than 10 bucks.

Never tried the stretch thing, but obviously you would need more heat than civic used. Maybe a heat gun for paint removal.

thanks so much for the info . imma try the heat gun thing first since i have one if its to hard il just go buy the pipe . would the pipe setup seal water and mud good ?