Help me choose carburetors for 1979 RD400F

[rearwheelslider]

I am open to all ideas related to which carburetors to run on my Daytona build. It will have stock porting/head, Wicked chambers, crossover, stock reeds(for now), Y boot with Uni foam filter.  I have ordered the CABLE that eliminates the oil pump cable(i premix) and allows for the use of different carbs. I would like to keep the stock size intake manifolds and y boot which is 33 and 44mm respectively. I would really like an easy to tune carb without a powerjet(can I just block it off on the PWK?).

Options include:
Stock 400 carbs(VM28)
Mikuni VM Round slides 30, 32, 34mm
Mikuni TM Flat slides 28, 32, 34mm
Keihin PWK 28, 33,35, 36mm

Any and all ideas are welcome!

[pdxjim]

Why aren't you using the oil injection pump?

... and when presented with the same set of options on my LC build a couple years ago, I went with genuine Keihin PWK28. I got the OEM Kawasaki KX100 ones from Partzilla for around $106 each including shipping. I think they've gone up to around $140 each now.

AFAIK, Y-boot and stock airbox boots fit just fine with the PWK28. And they don't have power jets.

[m in sc]

IMHO the pwks (legit ones) are the easiest to tune. keep in mind, anything over stock you're limiting the intake options. That being said, you can get plenty of power out of non daytona VM28's (400 or 350 ones)  and easy to tune overall and everything works/fits. also allows the use of a K&N an y-boot.

the other carbs will pretty much require running all foam unis (do not run pod k&n or other filters with flat backs). My suggestion is probably the VM30 or tm 28's. the vm30 is a hair over stock but very tunable.

the last rd i built i just ran jetted stock VM28s  and i have a box of pwks, tms, etc, and the vm28s did just fine with similar mods.
.02

[This Old Daytona]

I have to say PWKs, while not as ultimately good as Mikuinis, they are easiest to tune. On a stock RD your great with 26-28 mm, 30s on a mild port.
 DONT be tempted to go larger...you'll get all the performance and drivability with those. IMO for a street RD stock size carbs or close Simply rule.
 HOWEVER..if your doing carbs spend the $50.00 buck and by ALL means buy some TDR  Tony Doukas reeds. Its almost "Free".
  Coupled with the carbs..you'll have a great bike...
 Just my opinion, others will most certainly vary 😂

[m in sc]

38mm on a stock rd? seems a bit... excessive. I was pulling over 50 RWHP thru a set of 30mm pwks.

[pdxjim]

38mm on a stock rd? seems a bit... excessive. I was pulling over 50 RWHP thru a set of 30mm pwks.

Pretty sure they meant 26-28mm

Dave "Mutts Nuts" Whattam in the UK told me PWK28 are good for 75+ hp on LC and RZ.

[rearwheelslider]

I have to say PWKs, while not as ultimately good as Mikuinis, they are easiest to tune. On a stock RD your good with 36-38 mm.
 DONT be tempted to go larger...you'll get all the performance and drivability with those. IMO for a street RD stock size carbs or close Simply rule.
 HOWEVER..if your doing carbs spend the $50.00 buck and by ALL means buy some TDR  Tony Doukas reeds. Its almost "Free".
  Coupled with the carbs..you'll have a great bike...
 Just my opinion, others will most certainly vary 😂

I will consider the PWK's. Thanks for sharing. My only concern with the Keihin is that not many of the community have ran them(based off the Jetting excel chart) and I would like the fact that everyone and their brother has a mikuni and jetting info is plentiful!

[pdxjim]

I have to say PWKs, while not as ultimately good as Mikuinis, they are easiest to tune. On a stock RD your good with 36-38 mm.
 DONT be tempted to go larger...you'll get all the performance and drivability with those. IMO for a street RD stock size carbs or close Simply rule.
 HOWEVER..if your doing carbs spend the $50.00 buck and by ALL means buy some TDR  Tony Doukas reeds. Its almost "Free".
  Coupled with the carbs..you'll have a great bike...
 Just my opinion, others will most certainly vary 😂

I will consider the PWK's. Thanks for sharing. My only concern with the Keihin is that not many of the community have ran them(based off the Jetting excel chart) and I would like the fact that everyone and their brother has a mikuni and jetting info is plentiful!

I'll post a few links to threads on Norbos UK forum. Tons of jetting info over there.

Still curious why you're not running the oil pump?

[rearwheelslider]

I have to say PWKs, while not as ultimately good as Mikuinis, they are easiest to tune. On a stock RD your good with 36-38 mm.
 DONT be tempted to go larger...you'll get all the performance and drivability with those. IMO for a street RD stock size carbs or close Simply rule.
 HOWEVER..if your doing carbs spend the $50.00 buck and by ALL means buy some TDR  Tony Doukas reeds. Its almost "Free".
  Coupled with the carbs..you'll have a great bike...
 Just my opinion, others will most certainly vary 😂

I will consider the PWK's. Thanks for sharing. My only concern with the Keihin is that not many of the community have ran them(based off the Jetting excel chart) and I would like the fact that everyone and their brother has a mikuni and jetting info is plentiful!

I'll post a few links to threads on Norbos UK forum. Tons of jetting info over there.

Still curious why you're not running the oil pump?

I ride a two stroke dirt bike and am very used to premixing. I like the control of knowing my mix exactly. I will not often be riding father than a tank of gas will take me. My oil pump is complete junk, it was sitting in water for years as the side cover collected rain water and it did not drain.

[m in sc]

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]

theres tons of pwks being run on rds. typically, jjh needle, 142-155 (maybe as high as 192) main jet, 38-42 pilot will get you super close. ;)

Good to know. I just pulled the trigger on PWK30 carbs! The engine side measures 35mm, filter side 50mm. I hope i can stretch the y boot over the 5mm larger intake bell.

[m in sc]

you have a lathe? 

[rearwheelslider]

you have a lathe? 

No Lathe but I have sandpaper and patience! lol

[m in sc]

lol. nooo. 

I dont remember the flange thickness on a pwk off the top of my head  but i turned my carb bellmouth down for my XR150 to fit the stock airbox inlet. 5mm is a big stretch but maybe? all foam unis work just as well though on the pwks.

on my xr, it was -just- enough to just not block the air passages but got close. been running well for over 1000 miles.

 

[rearwheelslider]

lol. nooo. 

I dont remember the flange thickness on a pwk off the top of my head  but i turned my carb bellmouth down for my XR150 to fit the stock airbox inlet. 5mm is a big stretch but maybe? all foam unis work just as well though on the pwks.

on my xr, it was -just- enough to just not block the air passages but got close. been running well for over 1000 miles.

 

How do you like the chinese clone carb? Run into any issues? I ask because... nevermind.