cheap AF pwk30 knockoffs on the 72R5/RD

[m in sc]

To be clear, I do have a few sets of genuine ones but wanted to try some of these since i know they are prolific out there. why? why not, i paid 55 bucks a pair .



I had a set of RD350 carbs on there, this bike has the eBay 350 cyl's on it, so its sort of a cheap build just to try the current garbage that's out there. TBH, so far everything's been good.

It ran really well w the stock carbs but as it is, the midrange was OK, but sort of lacking. before throwing th set of dave-f modded carbs on that i have, i figured id go this way. I wanted to use the stock y-boot, so the steel adapters they have out there, sorry, suck. bad. they partially block the airjet, so i fired up the lathe and made the adapter rings out of some scrap 6061. 50mm id on carb side, 42mm ID thru the middle, 46mm OD on the y side (stock is 45). tapered the cut and radiused it so it all matched and this is what i came up with. they actually press on the carbs but I used an M4 screw to hold it just incase things shrink when air fuel runs thru them (yes regular unis would have been fine)











as far as the oil injection, i used some spare oil nipples i had off the TZR intakes i replaced, drilled a 3.8mm hole and pressed them in the top of the carb, this can be done with a banjo and bolt, or a stock rd oil nozzle replacement as well.



also compared to a stock 28:







on the bike:





test running, and playing w the needle, the jetting seems to be.. pretty spot on w/a 40 pilot (had a 38) and a 140 main (was 135) . needle that cam in the carb (no numbers but comparing to a JJH i have on hand... it looked the same) was good, would up in middle. 2nd clip, it pinged a bit, 4th clip id stumbled.

:for posterity, this bike has FPP chambers, no porting, rm100 v-force reeds, and a cdi with a curve for ignition.

plug check looks good, after about 25 miles: (on an 82 degree morning with swamp-ass humidity)

(flash makes this one look a bit whiter/grey that it actually is)





just figured i'd share this, especially for people that aren't familiar w the pwk style carb.

[Kawtriplefreak]

  

[elliottles1]

m in sc,

i have used these carbs a lot on various projects, always with very pleasing results, however, estimating initial jetting is always pure guesswork as the jet sizes use a different scale to mikuni carbs, so, my question is, in your post are you using mikuni scale or "pwk"?

cheers
les.

[m in sc]

pwk. one thing i always aim for is using the ones with the keihin long hex (main) jets.

[elliottles1]

hi again,

this guide might be of interest to anyone thinking of using these carbs.

http://www.mid-atlantictrials.com/instal.html

cheers
les.

[kpke]

Interesting stuff. The owner of this unusual RZ500 engined bike was quite proud of the fact that he used $30 china carbs on it. He had to make new intakes. It sounded pretty good.

[m in sc]

elliottles1 thats a great link, thanks.

I mean, they work great. comparing them side to side w 'legit' ones.. there really isnt any difference overall. there are, absolutely, really bad ones out there as well.

I rode the bike out last night to abieknight of sorts, ran perfect, on way home jumped on the interstate, hit 100 in 5th (it has a 6 speed in it)  on the merge ramp onto 77s, and had no issues riding hwy then back into town. no ping, no surging, just.. good.

[Jung]

Very cool, thanks for sharing! I'm tempted to try a pair, any reason you went for the 30s over the 28s? Can you use the stock throttle cables? Genuine keihin jets? (sorry for all the questions!)

[m in sc]

well, I knew it could pull them. 28s would have been fine though.  yes use stock low top cables and yes genuine keihin brass.  when looking for them make sure the spare jets they show are hex (they usually show them in the ad) and it's good to go. the round jet ones i've seen are near impossible to figure out whats going on IMHO

[Jung]

That's super helpful, ta!

[rodneya]

Those chinesium carbs have definitely got better quality wise, just dont be tempted to get the ones with the see through bowls.
There are even stores selling the knock off carbs with genuine Keihin Jets, needles and springs. Not super cheap though.

https://westcoastatvparts.com/shop-1/ols/products/28-pwk-carburetors

[elliottles1]

rodneya,

whats the problem with the clear bowl types please?

cheers
les.

[dgorms]

hi again,

this guide might be of interest to anyone thinking of using these carbs.

http://www.mid-atlantictrials.com/instal.html

cheers   
les.

Wow! I just learned a lot, thanks.

[rodneya]

rodneya,

whats the problem with the clear bowl types please?

cheers
les.

They leak and crack very easily when tightening the bowls

[elliottles1]

ok, thought it might be a running issue.
les.