Help me choose carburetors for 1979 RD400F

[Brad-Man]

You may want to try wintergreen oil and acetone or xylene mixture to soak the yboot carb ends in for a while to make it very pliable and then stretch over the PWK's - that worked for my 28's.

[m in sc]

for that bike its pretty good, not going to lie. the machining quality was top notch out of the box and uses genuine keihin jets. I mean, i put it on a brand new bike because the original carb just sucks.  Ive used knockoff pwks before, but ive learned, IF you go that way, use ones with hex jets, the round jet main ones are very hit and miss

[rearwheelslider]

You may want to try wintergreen oil and a stone or xylene mixture to soak the yboot carb ends in for a while to make it very pliable and then stretch over the PWK's - that worked for my 28's.

Good call! Maybe some boiling water too. Thanks for the input!

[rearwheelslider]

for that bike its pretty good, not going to lie. the machining quality was top notch out of the box and uses genuine keihin jets. I mean, i put it on a brand new bike because the original carb just sucks.  Ive used knockoff pwks before, but ive learned, IF you go that way, use ones with hex jets, the round jet main ones are very hit and miss

Nice! Dare I linked the ones I bought? Okay...

I am thinking I will block off the power jet to simplify tuning.

[m in sc]

ive used those.

[pdxjim]

for that bike its pretty good, not going to lie. the machining quality was top notch out of the box and uses genuine keihin jets. I mean, i put it on a brand new bike because the original carb just sucks.  Ive used knockoff pwks before, but ive learned, IF you go that way, use ones with hex jets, the round jet main ones are very hit and miss

Nice! Dare I linked the ones I bought? Okay...

I am thinking I will block off the power jet to simplify tuning.

Uh ... you bought them off Amazon?  Generally speaking, when it comes to stuff like this, you get what you pay for.  $30 carbs are not the same as $130 carbs.

[m in sc]

not all cheap carbs are created equal. im serious, in my experience, the ones that come with the round main jets are the ones to avoid. the rest are way better than they should be. I paid 46? bucks for the one i pictured above and honeslty.. the machining and finish was better than the TM 32s on the hybrid.

[This Old Daytona]

Yes a typo in my part. 26-28 mm is all you will ever need.
 26 mm carbs WILL support a 70 h.p. RZ/ Banshee ,28s even better
 CT racing will prove it to you in front of your eyes.

 I wasted $500 on PWK 33 mm Airstrikers/intakes for my Banshee and they proved it to me in front of my own eyes that,(stock) carbs DO THE SAME. Each laid down 70.h.p. and  equal power delivery, the 26s actually showed better power down low.
 The Mikuni TMs and PWKs do look quite nice though...lol.

But from here in our .it's 26-28s for me..no matter the carb.

Also for a street RZ..26s get almost 2xs the MPG.
 My friend & I both have modified Banshees mine is 385  MX ported stock cylinders 4 mil w 33s PWKs.
 His a CPI PV Cheetah 400 cc stock stroke crank w 35 PWKs.
 Both our Quads drink 6 gallons of fuel in about 45-60 minutes if hard riding. Our friends stock stroke,dune ported Banshee w stock carbs easily goes 2+ hrs on 6 gallons.

 So for a street RZ it's a NO BRAINER. 👍
IMO ONLY road race and drag bikes benefit from big carbs, for road use small carbs are better performers w better acceleration whatever it counts.
 I know others may take issue this...but after 40 yrs of RDs& RZs I'm sticking w what works for me..
 Good Luck 👍
 

[m in sc]

no, i agree. my tm 32s were actually a downsize from 34's, on a street bike it made a big difference and lost really nothing.

[John Ritter]

rearwheelslider, we have a RD400 that is ported and piped and our street engine runs modified VM28's. The roads in my area our somewhat hilly and twisty and the 28's work great.

[pdxjim]

This thread may be of some interest:

https://rdlccrazy.proboards.com/thread/47895/pwk28-vm30-on-4l0

[m in sc]

My TZR came stock with 28s, and will keep them, but its also a 250 @ 48-50 hp. the hit at top end is better with slightly larger carbs on rds but it also boils down to port work, pipes used, etc.  The rideability on my bike with 32mm flatslides is excellent, and, it gets to 11k FAST. smaller carbs will after a point affect the wot climb speed. (if that makes sense). JUst depends, but, in 95% of the situations, nothings needed over 30mm

[rearwheelslider]

I changed my order from the PWK30 to the PWK28. Thanks for the input, guys!

Yes I bought knock off carbs, but I have had relative success with them. As our friend stated, if these are junky(round head jets) I can just return them super easy thanks to Amazons return policy. However, I think at the moment, they will do much better than the stock 2v0 carbs I was originally going to run. Honestly, times are tough money wise but I totally get why you say you get what you pay for and its the truth. But this isnt a safety item like a brake hose or something...

Regarding the jetting of a PWK 28 on an RD400f with Wicked chambers, crossover, y boot/Uni foam... What are some good baseline jetting numbers? I am gonna order up a range of a few genuine keihin jets next and need a ballpark. I looked at the excel jetting poll and saw no pwks being ran. However on the link showed above, a guy was running --

"You Will however need; jjh needles.. 130 mains and 40 airs
Suggest ONLY Genuine Keihin Parts... as there IS difference."

Good starting point?

[m in sc]

going to need bigger mains. reply #9 i stated:

theres tons of pwks being run on rds. typically, jjh needle, 142-155 (maybe as high as 162) main jet, 38-42 pilot will get you super close. ;)

[rearwheelslider]

going to need bigger mains. reply #9 i stated:

theres tons of pwks being run on rds. typically, jjh needle, 142-155 (maybe as high as 162) main jet, 38-42 pilot will get you super close. ;)

Awesome, Thank you sir!