Jump to content

Round Slide PD Pumper Carb?!?!

Recommended Posts

I know I read something on TT in the last week that was mentioning a PD Pumper Carb that was from an overseas Honda 350 model...

I have no idea where I was reading it but I think SteveThe  was involved...

Would love some info... FCR carbs are my #1 with a bullet hands down favorite performance 4 stroke carbs.... But.. I would love to mess with a pumper PD...

The 04-05  TRX450R models came with 42mm PD round slide pumpers... I was unaware of other models

 

Share this post


Link to post
Share on other sites
9 minutes ago, mixxer said:

I know I read something on TT in the last week that was mentioning a PD Pumper Carb that was from an overseas Honda 350 model...

I have no idea where I was reading it but I think SteveThe  was involved...

Would love some info... FCR carbs are my #1 with a bullet hands down favorite performance 4 stroke carbs.... But.. I would love to mess with a pumper PD...

The 04-05  TRX450R models came with 42mm PD round slide pumpers... I was unaware of other models

 

:lol:

IMG_3991.PNG

Share this post


Link to post
Share on other sites

What a bummer....

When I zip through threads I stop when I see someone I know , and know that they are in the know, to read input from them so I don't waste too much time reading threads, ya know??

 

I thought I read round slide PD off non USA Honda 350... And thought you were involved.... Getting old sucks... Now where did I put my truck keys....

Edited by mixxer
  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, DaveCR said:

FWIW, the '90s XR250L had a PD pumper carb. 

Thank you

Share this post


Link to post
Share on other sites

If you stopped wasting money on carbulators you don't need you might could justify spending more on a proper shock!  Just sayin'...........:)

The CRF230F ain't no big inch Harley Davidson or Chevrolet, she is a finely tuned precision instrument who would not appreciate having raw fuel spewed into her causing all kinds of AFR issues. 

What are your plans for a pumper carb?  What issues are you looking to remedy that the OE PD has?  Please enlighten us oh great Lord of Combustion.

  • Like 1

Share this post


Link to post
Share on other sites

Ideally the pumper carb would be an FCR, but in general pumper carbs are impossible to beat for throttle response....

The bigger bore carb you pick per engine size, the longer the delay for rpm to create adequate vacuum signal for proper fuel delivery... Logical and straightforward... Whack open a big carb from a lesser opening... And you will be down on power in a radically lean mode until rpm can increase enough to create adequate draw through the main circuit...

Unhook the pump linkage from you Holley carbed hot rod V8 and mash the throttle and see what happens... Huge lag, lots of stumble, likely stall.... Hook the accel pump linkage back up and light up the tires when you nail it...

The "cure" for not having an accelerator pump has always been to size carbs smaller and with slightly rich low rpm jetting ... Slightly rich on bottom coupled with a smaller bore carb will get back to correct AFR quicker since it starts out rich and hits vacuum levels quicker via it's smaller bore....

So... Now decide you want a bigger cab for better top end power... You need to switch to either a flatter slide carb with sharper vacuum rise over the main circuit... Or better yet... An accelerator pump carb that sprays fuel proportionate to change in throttle opening... Much more power and response up to the point where vacuum is operating the correct fuel circuit...

The FCR carbs employ both the accelerator pump and the flat slide and they are an undeniable advantage over even a round slide pumper carb....

Now... As far as I have read ... People have talked about adapters and intake mismatches with the pwk carb... While the xr250 carb is basically bolt on, right down to throttle cables...

So naturally I was wondering about pd style carbs that are "bolt on" to the xr250... Since that would likely mean bolt on to the 230 as well...

If the xr250l or xr350 pumper carbs are a direct fit...while having a bigger bore...it would have much better bottom end response and pull than simply using an xr250r carb, while making for better top end power ...

Fun to think about

Share this post


Link to post
Share on other sites
50 minutes ago, MetricMuscle said:

If you stopped wasting money on carbulators you don't need you might could justify spending more on a proper shock!  Just sayin'...........:)

The CRF230F ain't no big inch Harley Davidson or Chevrolet, she is a finely tuned precision instrument who would not appreciate having raw fuel spewed into her causing all kinds of AFR issues. 

What are your plans for a pumper carb?  What issues are you looking to remedy that the OE PD has?  Please enlighten us oh great Lord of Combustion.

Prior to the move to fuel injection, all of the competition 4 strokes , finely tuned instruments all... Were using accelerator pump carbs.... 

Share this post


Link to post
Share on other sites
2 minutes ago, mixxer said:

Prior to the move to fuel injection, all of the competition 4 strokes , finely tuned instruments all... Were using accelerator pump carbs.... 

Were the OE carbs pumper carbs or were the competition 4 strokes running FCR carbs ?

Share this post


Link to post
Share on other sites
1 minute ago, MetricMuscle said:

Were the OE carbs pumper carbs or were the competition 4 strokes running FCR carbs ?

FCR carbs were standard equipment on all... All the Jap bikes, and European bikes... Street, dirt...all of them...

So you could call fcr carbs OE carbs since they were all on the bikes off the showroom floor...

  • Like 1

Share this post


Link to post
Share on other sites

Performance quads all ran the FCR carbs too... TRX and YFZ

Share this post


Link to post
Share on other sites

Our obsession with performance building everything is all just mental masturbation , when you get right down to it...

 

  • Like 1

Share this post


Link to post
Share on other sites
33 minutes ago, mixxer said:

FCR carbs were standard equipment on all... All the Jap bikes, and European bikes... Street, dirt...all of them...

So you could call fcr carbs OE carbs since they were all on the bikes off the showroom floor...

What streetbikes came with FCR carbs?

I've seen plenty of roadrace bikes with aftermarket FCR carbs, back in the day.

Share this post


Link to post
Share on other sites
11 minutes ago, MetricMuscle said:

What streetbikes came with FCR carbs?

I've seen plenty of roadrace bikes with aftermarket FCR carbs, back in the day.

I'm probably wrong on assuming the street bikes had fcr carbs... 

They were probably skipped and went right to fuel injection for emissions compliance advantage.... 

I know my Sudco catalogs were packed full of ganged FCR setups for street bikes... Although all my interest was for quads and dirt bikes and methanol jetting on some...

  • Like 1

Share this post


Link to post
Share on other sites

So has anybody tried the XR250L carb with the pumper? I found one and think I might buy it and see if I can make it work. Looks to have a cable choke thats on the R.H. side and the intake bell looks smaller in pictures. Seems cheaper and easier to install than a PWK. Thanks.

  • Like 1

Share this post


Link to post
Share on other sites
55 minutes ago, ricky racer said:

So has anybody tried the XR250L carb with the pumper? I found one and think I might buy it and see if I can make it work. Looks to have a cable choke thats on the R.H. side and the intake bell looks smaller in pictures. Seems cheaper and easier to install than a PWK. Thanks.

And it's designed for a 4 stroke from the beginning

  • Like 1

Share this post


Link to post
Share on other sites

I find the stock design of the fcr pretty useless without the factory pro needle jet emulsion tube modification. Fuel gurgles into the motor rather than perfumes it's outright horrible. In addition the Athena dual spray helps bottom end. 

Im not sure I believe even a well set up fcr works that well. The PWK perfumes fuel into the little 230 motor and that's what the motor wants for great bottom end.  

Share this post


Link to post
Share on other sites
57 minutes ago, stevethe said:

I find the stock design of the fcr pretty useless without the factory pro needle jet emulsion tube modification. Fuel gurgles into the motor rather than perfumes it's outright horrible. In addition the Athena dual spray helps bottom end. 

Im not sure I believe even a well set up fcr works that well. The PWK perfumes fuel into the little 230 motor and that's what the motor wants for great bottom end.  

Come on Steve, the fine atomization of fuel has always been the goal... From the first carb ever made... It's not a new concept or new design goal...

The FCR carb has been the end all carb  for bikes for me out of all the history of 4 stroke performance... Incredible power and response so sharp it feels like the shadow of your hand on the throttle is enough to start acceleration... Preemptive response if ever there was...

When first setting up the 04 trx450r models for competition I said I was thankful that Honda saw fit to put a pumper carb on the trx from the factory... 42mm round slide ... Worked well... After setting up a few fully modded trxs one of the flattrack guys was going to make a trek from Kansas to Michigan to do some jetting and cam testing on my dyno ... He had told me I wouldn't believe the response he picked up by swapping out his 42mm OEM carb for a 40mm FCR... I was skeptical... But it didn't take but one ride for me to order an FCR for my shop TRX... Truly awesome response... We dynoed the carbs back to back and the 40mm fcr matched the top end power of the 42mm round slide...  No doubt due to the choke butterfly and it's restriction on the OEM carb.... Now when Sredrum taperbored the FCRs to 43.5mm... top end went up by 3hp on the 450s... If you had 57 before, you had 60 after... Being longtime friends with Chris, I had so very much tuning time on the FCRs... Before I eventually sold my dyno to Chris , we had spent many weekends doing nothing but swapping, tuning, and Dyno and track testing milk crates full of his modified FCRs... I was fortunate at that time to have a 20 acre test track that you would be looking out the shop window at while you were doing Dyno runs... Gotta back to back test Dyno and track to validate... Take notes.. modify ...repeat ...

 We had tested the the perforated factory pro tube quite a bit on 450s in 04 and 05... When AFR and accel pump squirt were Dyno dialed in there was zero difference on the dyno and the same felt off the Dyno...

You have to know that drilling holes in a tube is nothing new or patentable and if it represented a true advantage there is nothing to stop the carb manufacturer themselves from employing the technique completely at their disgression....  You have to question when someone is "selling" you on a subject where they have cash to gain.. if someone makes a video with intent  to get your money, that video is going be made with intent to sell ..Emperor's New Clothes syndrome... :

"Everyone else knows this is wonderful, and if you don't agree, then there is something wrong with you"

Keihin is a subsidiary of Honda Corp... One of the biggest and best engineering powerhouses the world has ever known...  And they make all the Keihin carbs pwk and fcr and pd and...etc etc

You have to consider how likely it is that the engineering juggernaut that made the engines AND the carbs... Completely missed on application and style... 

I have used the Athena dual spray nozzle.. and it worked , but so did the OEM nozzle, and so did the OEM nozzle modded for free by Chris/Sredrum with every taperbore job ... But the ones most succeptible to clogging were the fine diameter of the Athena nozzle...

I don't doubt that the pwk works fine on the 230... Not even a little bit...

I'm just finding it fun to explore other options....  If 20 dudes have pwk's, then it might be fun to have a 30mm pumper that bolts right up and looks somewhat stealth like a stocker...

 

  • Like 1

Share this post


Link to post
Share on other sites

The factory pro modified needle jet is the same holes drilled in every Keihin and Mukuni carb made for a 4T. That is except the FCR? I consider it a defective carb without the modification. The modification opens the main air jet by way of drilling that circuit into the bleed needle jet. 

A hugh hole exists in the powerband of the WR250's and 450's near off idle. Without that mod. they are very hard to ride. I own four WR450 and have done countless others. All the riders have said the same thing before and after the mods. 

Hum the 4th one is fuel injected. I guess that one doesn't count. :excuseme:

Edited by stevethe

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×