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 (https://hvccycle.net/yamaha-performance-throttle-cable-for-yamaha-rd-250-350-400-no-oil-pump/?mc_cid=ca8e3b2713&mc_eid=235f3a8d36) 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!
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.
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
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 😂
38mm on a stock rd? seems a bit... excessive. I was pulling over 50 RWHP thru a set of 30mm pwks.
Quote from: m in sc on December 05, 2023, 09:17:56 AM38mm 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.
Quote from: This Old Daytona on December 05, 2023, 12:01:26 AMI 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!
Quote from: rearwheelslider on December 05, 2023, 10:40:41 AMQuote from: This Old Daytona on December 05, 2023, 12:01:26 AMI 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?
Quote from: pdxjim on December 05, 2023, 10:42:55 AMQuote from: rearwheelslider on December 05, 2023, 10:40:41 AMQuote from: This Old Daytona on December 05, 2023, 12:01:26 AMI 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.
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. ;)
Quote from: m in sc on December 05, 2023, 10:57:36 AMtheres 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.
you have a lathe? :science:
Quote from: m in sc on December 05, 2023, 01:06:44 PMyou have a lathe? :science:
No Lathe but I have sandpaper and patience! lol
lol. nooo. :dawg:
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.
(https://2strokeworld.net/wp-content/uploads/2023-xr150l/carb/xr150-carb-swap-stuff_10-rotated.jpg)
Quote from: m in sc on December 05, 2023, 03:18:34 PMlol. nooo. :dawg:
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.
(https://2strokeworld.net/wp-content/uploads/2023-xr150l/carb/xr150-carb-swap-stuff_10-rotated.jpg)
How do you like the chinese clone carb? Run into any issues? I ask because... nevermind. :whatever:
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.
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
Quote from: Brad-Man on December 05, 2023, 03:50:17 PMYou 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!
Quote from: m in sc on December 05, 2023, 03:51:38 PMfor 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.
ive used those.
Quote from: rearwheelslider on December 05, 2023, 04:16:13 PMQuote from: m in sc on December 05, 2023, 03:51:38 PMfor 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.
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.
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 👍
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.
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.
This thread may be of some interest:
https://rdlccrazy.proboards.com/thread/47895/pwk28-vm30-on-4l0
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
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?
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. ;)
Quote from: m in sc on December 06, 2023, 12:10:24 PMgoing 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!
Would you recommend the TDR reeds or YZ reeds?
Quote from: rearwheelslider on December 06, 2023, 12:13:58 PMWould you recommend the TDR reeds or YZ reeds?
For you, I'd recommend kx100 v384a Vforce3 reeds.
^ agreed
(https://i.ibb.co/zGQ4qZk/IMG-5531.jpg)
im running those rm reeds on the lightweight with a fairly radically ported motor (where i figure out that they would work) & set of PJ34 keihins thru them, they flow plenty for that so they will handle smaller carbs zero issues
PWK 28's on my Rd400F update:
First start was with 155 mains, JJH needles on third clip, 40 pilots, 2 turns out. Started and idled okay, but would not rev out past 4k.
I then dropped needle to first clip(full lean), got a little better.
I then went to 145 mains, same needles/clip positions, 38 pilots, 1.5 turns out. The low speed fueling is great, gonna keep that in there.
I then dropped mains to 138's. Much improved and will pull through the rev range. Good power. Still feels a tad rich up top but I will need to ride it for a bit to see how it pans out.
interesting the main is so low. however, im used to 350s , the swept volume of a 400 is more and therefore -should- cause a stronger vacuum signal which probably explains a 138.
Mutts suggested to me stopping down the airscrew to .5-1 turn out max.
Said 1.5 (which is generally a good starting point) is usually too much air and they like it richer just off idle regardless of pilot size.
Worth a try before detailing the mains as (so I've been told) the overlap/influence of one circuit to the next is greater on PWKs than some other carbs (Mikuni)🤷�♂️
As always, take my comments with a grain of salt as I'm usually just repeating what the real smart guys have said.
that's all dependent on the slide cutout, jim.
Quote from: m in sc on December 22, 2023, 11:48:58 AMinteresting the main is so low. however, im used to 350s , the swept volume of a 400 is more and therefore -should- cause a stronger vacuum signal which probably explains a 138.
Something to note.. These are the knockoff PWK's and they do have a powerjet. The powerjet orifice is TINY, not sure how much it is affecting the wide open fueling if at all. But if it is, it explains the reduced main size.
Either way, the rear tire is not holding air and they are from 1988, so not much ride/tune going to be happening. Neighbors loving the noisy chambers, too!
true. the powerjets that come in those i think are about equivalent to a 17.5 or 20 mikuni pilot jet size, they are very small
I hope we aren't confusing Keihn jet numbers with Mikuni large hex numbering. Keihn jet are numbered according to their diameter IIRC, so a Keihin #138 is roughly equivalent to a 230 or so large hex mikuni.
I have a bit of an issue maybe you guys can help me with. The throttle cable is the one from HVC. Dual cable, made to fit PWK, TM, stock carbs.
I currently have the short adjusters on my carbs and the throttle cable adjustments are all near maxed. When the cable stretches, I wont have much adjustment left at all. Also the angle of the cable is a bit much at the carb top.
Do you know if these angled adjusters will take up enough cable slack, but not make the cable too short? I cannot seem to find them, other than Ali Express. Another source and more info would be appreciated!
I used these off Amazon. They worked perfect to fit a genuine standard LC cable to my genuine PWKs.
Sudco Adjuster Asmbly 40 Degree... https://www.amazon.com/dp/B00T6J9VHY?ref=ppx_pop_mob_ap_share
^ive used those as well.
Quote from: m in sc on December 26, 2023, 02:59:17 PM^ive used those as well.
You can remove the lower locknut and/or cut more threads if more adjustment is needed.
Quote from: pdxjim on December 26, 2023, 02:26:35 PMI used these off Amazon. They worked perfect to fit a genuine standard LC cable to my genuine PWKs.
Sudco Adjuster Asmbly 40 Degree... https://www.amazon.com/dp/B00T6J9VHY?ref=ppx_pop_mob_ap_share
Frick yea, Thanks guys!
Hey guys, I am finally putting some miles on to the bike and its a ripper! Love it.
I do have a question. The idle seems a bit uneven. The carbs have been synchronized and all adjustments are equal. To do this, I removed spark plugs from opposing cylinders and let the bike run on one cylinder. I adjusted the idle to allow the bike to run at 1k rpm on each cylinder, then installed both plugs and turned back the idle adjusters equally.
The left side cylinder has a stronger idle, it puff puffs seemingly every combustion stroke, while the right side will puff puff much less often(normal two stroke behavior), like once every couple seconds.
To compensate for this, it liked a half turn in on the left and screw and a half turn out on the right. The idle is much better like this. Above idle it is perfectly even. Is this indicative of an air leak on the left cylinder?
double check float level. if its richer on the RH cyl, id bet its too high. (pull plugs and check them after idling)
Quote from: m in sc on January 18, 2024, 12:07:44 PMdouble check float level. if its richer on the RH cyl, id bet its too high. (pull plugs and check them after idling)
Float level was checked and adjusted. Same condition. I then swapped the carbs left to right and the high idle followed the carb. I pulled both carbs and inspected them. The floats were set very high(low fuel level in bowl). I adjusted them and the condition remained. I did inspect the jets, and somehow the mains are Mikuni branded(square in a square logo) 138's. I believe the jet sizes are the same numerically from keihin to mikuni and they appear physically identical to the Keihins that I have. Any objections to me leaving those in there?
The pilot jets are off brand and the printing is different between the two. Turns out, 38's are the ones I dont have genuine versions of... But I think this may fix the idling issue.
Regarding the Needles, I am running the jjh. The bike seems a bit fat in the middle throttle input. Thinking of a leaner needle such as JJJ or JJK. Thoughts on this?
ive run jjj's as well.