I'm interested in hearing all rider feedback on any RB Designs carb mods on 125 cc bikes. I'm primarily interested in 38mm PWK and before/after results.
More info on RB Designs carb mods
More info on RB Designs carb mods
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Hi everyone,
As you all know, Coffee (Dean) passed away a couple of years ago. I am Dean's ex-wife's husband and happen to have spent my career in tech. Over the years, I occasionally helped Dean with various tech issues.
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Over the past couple of weeks, I’ve been working to migrate the site to a free cloud compute instance so that Woodschick and Dirtdame no longer have to fund it. At the same time, I’ve updated the site to a current version of XenForo (the discussion software it runs on). The previous version was outdated and no longer supported.
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Thanks for your patience and support!
125-200cc RB Designs Carb Mods on CR/WR125 bikes
- Thread starter MattR
- Start date
surfer1100
Husqvarna
AA Class
It works quite well, improved bottom and mid, but for some reason I feel it makes the needle a little more touchy though.
Then again I've never had much luck finding a needle and clip position to stick with on these tiddlers, even given my fairly consistent temperatures.
Then again I've never had much luck finding a needle and clip position to stick with on these tiddlers, even given my fairly consistent temperatures.
WOW!!! This is must-have item for all bikes
A few weeks ago, I sent my 38mm PWK air striker to RB Designs. We exchanged several emails and I went with his recommendations. Ron installed his divider plate on the outlet side (i.e., reed valve side), did some low speed circuit mods, and added his RB mixture screw.
First Impressions:
His turnaround time was very quick. I got my carb back in a few days and my first impressions were good. The carb was machined for the divider plate and overall workmanship was top-notch! The divider plate reaches all the way to the slide and matches the slide profile very closely. So the carb bore greatly reduces it effective diameter at smaller throttle openings. The RB mixture screw is also very nice! There is a second spring to help maintain your adjustment. The knob is knurled for easy turning and has an indicator line to help note your setting.
Ride Impressions:
I rode my bike just before shipping out the carb, so I had a good baseline to go from. I also left my winter jetting setup exactly the same before his modifications. My first observations was that my bike started up easier. A couple quick jabs on the kicker and the littler 125 fired to life.
I did my usual warm-up and rode easy for a few minutes down the trail. I immediately realized that this was not the same bike! This modification has made a major transformation. Previously, my throttle roll-on was tame and lacked low end response. I used to think this was just a "125 trait" and lived with it. Well, let me tell you... 125's can have some serious bark and low end response... you just need Ron to work his magic. My bike feels like someone just installed a 144cc big bore kit. The changes from idle through mid range were that dramatic.
My CR125 now runs flawlessly throughout the entire range. You get a very small bore at low end (increasing torque), then as you roll-on the throttle, the bore opens proportional to the slide action and results in the same screaming top end of the 38mm bore. I purposely short shifted and tried to bog my bike. It always pulled strongly when rolling on the throttle. This thing performed awesome!
I would highly recommend to other members.
A few weeks ago, I sent my 38mm PWK air striker to RB Designs. We exchanged several emails and I went with his recommendations. Ron installed his divider plate on the outlet side (i.e., reed valve side), did some low speed circuit mods, and added his RB mixture screw.
First Impressions:
His turnaround time was very quick. I got my carb back in a few days and my first impressions were good. The carb was machined for the divider plate and overall workmanship was top-notch! The divider plate reaches all the way to the slide and matches the slide profile very closely. So the carb bore greatly reduces it effective diameter at smaller throttle openings. The RB mixture screw is also very nice! There is a second spring to help maintain your adjustment. The knob is knurled for easy turning and has an indicator line to help note your setting.
Ride Impressions:
I rode my bike just before shipping out the carb, so I had a good baseline to go from. I also left my winter jetting setup exactly the same before his modifications. My first observations was that my bike started up easier. A couple quick jabs on the kicker and the littler 125 fired to life.
I did my usual warm-up and rode easy for a few minutes down the trail. I immediately realized that this was not the same bike! This modification has made a major transformation. Previously, my throttle roll-on was tame and lacked low end response. I used to think this was just a "125 trait" and lived with it. Well, let me tell you... 125's can have some serious bark and low end response... you just need Ron to work his magic. My bike feels like someone just installed a 144cc big bore kit. The changes from idle through mid range were that dramatic.
My CR125 now runs flawlessly throughout the entire range. You get a very small bore at low end (increasing torque), then as you roll-on the throttle, the bore opens proportional to the slide action and results in the same screaming top end of the 38mm bore. I purposely short shifted and tried to bog my bike. It always pulled strongly when rolling on the throttle. This thing performed awesome!
I would highly recommend to other members.
highdez1981430cr
Husqvarna
AA Class
MattR,
Did he taper bore and plate both ends of the carb for $125?
Did he say how much he bored the spigot?
Did he taper bore and plate both ends of the carb for $125?
Did he say how much he bored the spigot?
highdez1981430cr;140770 said:
No boring was done. Since my carb was already 38mm and my bike is a 125, his recommendation was the divider plate and circuit mods that I described above. The divider was done only on the one side. Ron has been doing carb mods for many years and many types of bikes. I went with his expertise.
Other bikes and engine sizes may require a totally different approach. For example, KTM's with the smaller 36mm carbs need the bore increased up to 39mm and divider plate installed. The GasGas bikes get even more tweaks and slide modifications. It would best to talk with Ron about the characteristics that you are after. He responds to his emails and provides great service.
water racer
Husqvarna
Pro Class
How does the RB divider plate compare to the scary fast one. What sort of idle circuit mods did he make? All I saw on the website was a hand adjustable airscrew.
Thanks, GP
Thanks, GP
RB divider plate is nothing like the Power Now products. I had a Power Now on my last bike and there was little improvement. The Power Now divider is shaped differently and only covers a portion of the carb bore. The RB divider is machined and welded to fit perfectly in the carb bore. It covers the entire length up to the slide. While installing the divider plate, Ron can also make the other low circuit mods to work together. The overall package works excellent and it boosts the signal strength of the low speed circuit making it work more effectively.
His site does have examples of carb mods for different bikes. You can only get his mixture screw if you have him do the mods. It requires some machine work to work properly.
http://www.rb-designs.com/carb.html
You may want to go to his home page to see all of his services.
His site does have examples of carb mods for different bikes. You can only get his mixture screw if you have him do the mods. It requires some machine work to work properly.
http://www.rb-designs.com/carb.html
You may want to go to his home page to see all of his services.
water racer
Husqvarna
Pro Class
Thanks, sounds like it is worth the time to ship it off, versus ordering a powernow.
GP
GP
vegtablebrain
Husqvarna
AA Class
I have a power now valve, Moose reed spacer and a power valve spring kit. All of these changes made an improvement. I think the power valve spring kit helped the most. The Moose reed spacer (same as a Honda CR 125) makes it more difficult to install and remove carb.
Photos of my carb modifications
Here is a couple pics of the divider plate.
Here is a view with the slide installed. Note the divider plate covers the full length of the bore up to the slide.
Here is a comparison of the RB mixture screw vs. the stock screw. Note the second spring to help maintain your adjustment setting. Nice!
Here is a close-up of the RB mixture screw installed. Adjustments are very easy now with gloves on.
Note: the OD is remachined to provide the proper profile to mate with the manifold boot.
Thanks Ron! You did an awesome job.
Here is a couple pics of the divider plate.
Here is a view with the slide installed. Note the divider plate covers the full length of the bore up to the slide.
Here is a comparison of the RB mixture screw vs. the stock screw. Note the second spring to help maintain your adjustment setting. Nice!
Here is a close-up of the RB mixture screw installed. Adjustments are very easy now with gloves on.
Note: the OD is remachined to provide the proper profile to mate with the manifold boot.
Thanks Ron! You did an awesome job.
typeone
Husqvarna
Pro Class
great pics, you just talked me out of the PowerNow for the 144 i added a PN to my TC, which was already jetted purrrfect, for a little more refinement. works well.
question for john01: did you ever send your stock TMX off to Ron? my WR144 gets here next week so i'm making a master list of mods. curious if anyone has feedback on an RB modded TMX... on the fence whether to grab the PWK from Motosportz.
i added a PN to my TC, which was already jetted purrrfect, for a little more refinement. works well.question for john01: did you ever send your stock TMX off to Ron? my WR144 gets here next week so i'm making a master list of mods. curious if anyone has feedback on an RB modded TMX... on the fence whether to grab the PWK from Motosportz.