$200 R&D Power Bowl fixes carb bog


39 replies to this topic
  • Ga450owner

Posted August 01, 2007 - 09:28 AM

#21

The problem with the current accelerator pump design is air entrapment. Whoever though no leak jet is a good idea, has no idea what is actually going on inside the fuel pump chamber.
Fuel in the float bowl, being tossed around from bumps and jumps, not to mention vibration turns into a froth. The accelerator pump located below the float bowl, receives all its fuel supply from this frothy mix of air and gas, because the pump chamber is not design to expel the entrapped air pocket that naturally accumulates, a dampened pulse is produced, similar to air in the brake lines. We all know how well hydraulic brakes work with air in the lines. The stock pump chamber has one fuel outlet hole located low in the pump chambers vertical wall, air having a tendency to rise to the top of the fuel chamber, has a difficult time being expelled. The stock pump chamber actually splits the fuel outlet hole into two holes, this is another point of concern, the air pocket will eventually build to the point that it is partially expelled, now just imagine for a moment, the outlet hole is slit into two holes, the expelled air has two ways to go, one way is back to the float bowl through the leak jet orifice, no problem, the other way is right through the brass nozzle into the venturi. The brass nozzle is a fuel ONLY device not an air nozzle, belching air through this nozzle will cause a severe bog.
My thinking was to reposition a hole at the highest point in the pump chamber, this would expel the entrapped air pocket much more efficiently, than I relocated the fuel outlet hole low in the pump chamber vertical wall, insuring that is remains a fuel only port. Now every time the pump diaphragm is activated, it automatically purges the air bubble out the top hole and back to the float bowl, now the brass fuel nozzle can remain a fuel only orifice.
That is a brief overview of my fuel pump design, the pump is only one of the five improvement built into the R&D Power Bowl.



great info Dean. What are the other 4 improvements the Powerbowl will provide?

thanks

  • gtguy

Posted August 01, 2007 - 10:47 AM

#22

The problem with the current accelerator pump design is air entrapment. Whoever though no leak jet is a good idea, has no idea what is actually going on inside the fuel pump chamber.
Fuel in the float bowl, being tossed around from bumps and jumps, not to mention vibration turns into a froth. The accelerator pump located below the float bowl, receives all its fuel supply from this frothy mix of air and gas, because the pump chamber is not design to expel the entrapped air pocket that naturally accumulates, a dampened pulse is produced, similar to air in the brake lines. We all know how well hydraulic brakes work with air in the lines. The stock pump chamber has one fuel outlet hole located low in the pump chambers vertical wall, air having a tendency to rise to the top of the fuel chamber, has a difficult time being expelled. The stock pump chamber actually splits the fuel outlet hole into two holes, this is another point of concern, the air pocket will eventually build to the point that it is partially expelled, now just imagine for a moment, the outlet hole is slit into two holes, the expelled air has two ways to go, one way is back to the float bowl through the leak jet orifice, no problem, the other way is right through the brass nozzle into the venturi. The brass nozzle is a fuel ONLY device not an air nozzle, belching air through this nozzle will cause a severe bog.
My thinking was to reposition a hole at the highest point in the pump chamber, this would expel the entrapped air pocket much more efficiently, than I relocated the fuel outlet hole low in the pump chamber vertical wall, insuring that is remains a fuel only port. Now every time the pump diaphragm is activated, it automatically purges the air bubble out the top hole and back to the float bowl, now the brass fuel nozzle can remain a fuel only orifice.
That is a brief overview of my fuel pump design, the pump is only one of the five improvement built into the R&D Power Bowl.


Let me ask you this, I don't have a bog problem, nor do I need more power (particularly low end). My issue is as a woods rider I tend to lug the motor at a relatively consistent low throttle (1/4 to 1/3). After a period of time at this throttle setting the bike will sometimes just quit, almost like a two stroke loading up. I've gotten to the point I can usually tell when it's about to occur. I've always considered it an cavitation or air problem. Have you had any experience or insight to this situation? (you may have answered this with you post) I just wanted bit of clarification before I took the plunge!

  • R1DEAN

Posted August 01, 2007 - 01:19 PM

#23

Let me ask you this, I don't have a bog problem, nor do I need more power (particularly low end). My issue is as a woods rider I tend to lug the motor at a relatively consistent low throttle (1/4 to 1/3). After a period of time at this throttle setting the bike will sometimes just quit, almost like a two stroke loading up. I've gotten to the point I can usually tell when it's about to occur. I've always considered it an cavitation or air problem. Have you had any experience or insight to this situation? (you may have answered this with you post) I just wanted bit of clarification before I took the plunge!


It sounds like the effects of the air pocket in the pump chamber, it dampens out the subtle diaphragm movement, causing a lean condition.

  • gtguy

Posted August 01, 2007 - 01:57 PM

#24

Is the power bowl going to help me out with this?

  • Kyle Prior

Posted August 01, 2007 - 02:13 PM

#25

From what I've gathered, mostly speaking with the guys at Zip-Ty is that with thier carb mod, the bog goes away, and it really helps a lot. They do run the Powerbowl on top of thier carb mod, and have said that it really helps in the races they do extreme elevation changes on, and all but eliminates the need to rejet for elevation changes. I will personally be doing the ZipTy mod on my 250f carb, as well as the Powerbowl.

  • WB450

Posted August 01, 2007 - 04:19 PM

#26

Zip Ty $100.00.

  • R1DEAN

Posted August 02, 2007 - 06:35 AM

#27

From what I've gathered, mostly speaking with the guys at Zip-Ty is that with thier carb mod, the bog goes away, and it really helps a lot. They do run the Powerbowl on top of thier carb mod, and have said that it really helps in the races they do extreme elevation changes on, and all but eliminates the need to rejet for elevation changes. I will personally be doing the ZipTy mod on my 250f carb, as well as the Powerbowl.


Ty Davis told me, after a bad crash, he is amazed at how much easier
the bike was to start with the R&D Power Bowl.:thumbsup:

Attached Thumbnails

  • LEAK-JET-cover-04.JPG


  • FLjoyride

Posted August 02, 2007 - 11:53 AM

#28

Nice drawing, is that solid works?

  • R1DEAN

Posted August 02, 2007 - 05:35 PM

#29

Nice drawing, is that solid works?


Yes, it is quite the lay out tool, I especially like the transparency feature.

Attached Thumbnails

  • LEAK-JET-cover-04.JPG


  • Yamaha4lyfe

Posted August 02, 2007 - 09:38 PM

#30

dean why don't you sponcer me and give me a free float bowl and ill represent you for b.c woods/ moto racing eh :D

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  • scottsyz

Posted January 02, 2008 - 02:12 PM

#31

I too have recently installed an R&D Power Bowl to my 2007 YZ450F. It IS everything that it is advertised to be !!!! To read my whole review of this bolt-on mod you may do so in the Product Review Section of Thumper Talk. Once again R&D Racing has a WINNER !!!!!!!

  • Wes Woodin

Posted January 02, 2008 - 03:13 PM

#32

It made my 08 run like a bat out of ____!:banghead: It's the deal!

  • JHV

Posted April 12, 2008 - 10:35 AM

#33

I know that this thread is an older one, but I'd like to add that I use Dean's Powerbowl and his Flex-Jet Remote Fuel Screw, and can confidently say that it addressed and remedied a number of common problems inherent in the FCR design. Dean has proven to be completely accessible, totally knowledgeable and more than willing to assist with any questions I've ever had pertaining not only to his products, but to the operation of the system as a whole. Unlike some products which claim great improvements and deliver nothing but a lightening of one's wallet, The R&D products work, they are extremely well made and do exactly what they promise.

Some have commented that the Zip Ty modification is all they need and that's just fine, but if they are so completely satisfied with the basic Zip Ty mod, why can't they see that the ULTIMATE Zip Ty Mod INCLUDES the POWERBOWL? Evidently, Zip Ty Understands the value of the product too.

In the MX world there are hundreds of scammers and junk purveyors just waiting to take your money. Then there are those companies and individuals who have developed a "better mousetrap" and offer it to the public. Separating the two can be difficult sometimes, but the R&D Products deliver what they claim. I won't run a bike without them. Just for our bona fides, We took the 2007 East Coast AMA//Toyota Trucks 125C East Arenacross Championship, The New Jersey State Championship (2007 125C) and the 2007 Raceway Park Track Championship (125C), so I would say that we have a little "Cred" in the performance department. I don't sell Dean's Product but I DO Endorse them wholeheartedly. I'm willing to speak to anyone who has a question about any of Dean's stuff from the perspective of a user rather than an employee or sales rep. Email me and I'll get back to you. (jim AT hre.com)

  • MX926

Posted April 12, 2008 - 10:58 AM

#34

Ever since the Power Now dvice came out back in 2003, there have been a slew of hop-up carb mods... I'm sure there is some gain to the RD Float bowl, as with powernows however with proper jetting, there is no bog problem. I had 03-04 YZ250F'S, 06-08 yZ450F'S and once I got the jetting dialed, there is absolutely no bog problem. My 08 can go from idle to wide open, with zero hesitation.

-If the RD Float bowl can improve a machine that currently has no bog-problem, than it is quite a product, and I look forward to hearing more about it in the future.

  • JHV

Posted April 12, 2008 - 01:13 PM

#35

-If the RD Float bowl can improve a machine that currently has no bog-problem, than it is quite a product, and I look forward to hearing more about it in the future.[/QUOTE]

Well I can tell you that it DOES improve a machine with no problem and here is how it does it;

By having the ability to adjust the leak jet with a minimum of fuss, you preclude all the bother that was previously associated with that particular task. You don't have to remove your bowl to change leak jets, you simply dial in the leak that works for you. Now if you have a bike that never needs a leak jet adjustment, you are one of the fortunate few and certainly don't need ANY product that addresses that issue.

The Flex-Jet Remote is another product that improves on current design. With the ability to adjust the fuel screw without having to twist the carb to the side to reach the fuel screw, you again make life easier for the rider or the mechanic. 450's don't have the problem as their carbs are high enough that you can get easy access to the bottom of the carb, but 250's are cramped for space. I would use it on a 450 as well because it's well made, easier to access (yes, even easier than an aftermarket fuel screw) and is engineered beautifully. Again, if you don't need to ever adjust your fuel screw, I envy you <G>

  • MX926

Posted April 17, 2008 - 05:07 AM

#36

What about on track performance? Will this RD float bowl make a good running, well jetted machine, run any better than it already does? I agree there are several benefits to this product. I'm just wondering if there is any bolt-on power noticed.

  • grayracer513

Posted April 17, 2008 - 08:19 AM

#37

I'm just wondering if there is any bolt-on power noticed.

From a float bowl? Don't be silly.

IMO, there are two reasonably legitimate improvements made by the Power Bowl. One is that it reduces fuel slosh around the jets. But this is rarely a problem with most FCR's in the first place, and most people won't notice a benefit from this.

The other is a little more real, and that is that the fill and discharge check valves in the accelerator pump well on the Power Bowl are somewhat improved over stock. The stock check valves don't always seat as they should, and the PB checks a a little more positive and consistent.

Otherwise, it offers the convenience of being able to dial in the leak jet size externally, without removing the bowl to do it, which would save some time, I suppose. But the reality is that once you settle on the right leak jet, there's almost never a need to change it, and if you did need to adjust some in the case of an extreme altitude change. you could just go up or down a size from where you were without having to research the matter.

Remember that the leak jet influences only the accelerator pump action, and the AP works only as the throttle is being opened. It has zero effect on the output of the engine under any steady state pull down a straight beyond the way the engine responds to the throttle opening suddenly.

Of course, it's very cool looking.

  • MX926

Posted April 17, 2008 - 02:48 PM

#38

My feelings exactly.

  • swatdoc

Posted April 17, 2008 - 04:35 PM

#39

I'd sure have a lot more money if I only spent it on things for my bikes I really NEEDED, instead of because it's trick or looks cool! :thumbsup:

  • x2468

Posted April 17, 2008 - 05:58 PM

#40

these are popular with the Ktm 450 and 505





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