Data Poll - RB Carb Mod for 200's

[RTL]

The intent of the thread is to acquire and compare data for the RB Carb mod for those of us with 200's. 220 owners please pipe in where value added since you have the most experience with this mod. 200 owners, list your setup data and results accordingly. Let's share data on this experimental carb mod. :D

2001 200, elevation 950, FMF Rev, TCII, Boyosen 607, Air box mod. Stock motor, no porting. Mobile 1 MX2T 40:1, 93 Octane pump gas. Ride MX/Woods 50/50.

CEK 3, 152, 42, AS 1/2 turn out (as delivered from RB)

Just received carb back from RB, installing soon. Will post results accordingly.

 

[Fred T]

Here's where I'm at:

cold temps below 40: CEK 4, 42/ 155
Temps 40-60 CEK 4, 40 and checking out 152
Temps above 65-70 CEK 3, 38, and probably 150 but not sure.
A/S turned about 1/2 turn but adjusted daily.

KDX 220, Boyesen 607, stock porting, FMF KG 30/TC II, BR8ES, 93 Oct pump gas-MX2T 40:1, Alpinestar boots and either a green or black Jersey, clear lenses on my goggles.

 

[RTL]

Fred T, you forgot to mention the big fat grin on your face! Ha.. Got to love it... Thanks for the data...

 

[Canadian Dave]

RTL did you catch the RB modified carb thread in the Archives? There's lots of info there too.

David

 

[jason]

I just installed RB carb. on my 99 KDX. First ride was in 3 acre field. Pilot seems to rich. I'm going to try one size smaller. A/s was at one turn out and I ended up going 2 1/4 out. That seemed to help out alot.

99 200,pro circuit pipe and silencer,boyseen power reeds,air box lid removed,92 octane hp2 32:1
400 ft,70 deg. 80% humidity
cek 3,42,152

 

[RTL]

Yes, I found it CD. Good info. I was thinking more info on current setups would be nice. Many have worked out the bugs since the last threads. Thanks.

 

[RTL]

Good stuff Jason. Where in KY are you located?

 

[Fred T]

Temps today about 70

so I'm at: 40 pilot, CEK #4, 152 mainjet. MX 2T@ 40:1, 93 Oct pump gas, 1200 feet, and I turned the a/s out 1/8 turn more. I really didn't ride today except on my street but I could tell it was rich b-4 with 155 main so I'm middle of the road planning on a ride next Sat when temps will be in the 60 (Predicted)

I have a feeling I will be on a 38 pilot real soon.

 

[acutemp]

RTL,
Fred's settings should be pretty close for you also. You should check with CanynCarvr as he done has a ton of testing with 2 stock ported 200'sand various needles. Of course to get the most out of your bike you will have to do some fine tuning as no 2 bikes are exactly the same. I am pretty confident that the CEK #3,4 is a great choice for a nice strong midrange boost on stock ported bikes with the typical mods. The BEL (there is no BEK)would be a good choice for a smoother transition. There are also some who still prefer the A taper needles, AEK,L although not many are still running these. These are settings with a #7 slide.--Dan

 

[BRush]

Originally posted by acutemp
There are also some who still prefer the A taper needles, AEK,L although not many are still running these. These are settings with a #7 slide.--Dan

Call me crazy, but I still run the AEK needle. My experience has been that it yields good linear power delivery for snotty woods riding. There is a price to be paid in the form of a brief flat spot when the slide opens past the divider plate, but it's not bad. I have JD's spreadsheet and some needles on the way from SUDCO to experiment a little more, in the hopes that I can have my cake and eat it too - but I'll only switch permanently if I can retain that linear delivery right from the bottom into the midrange.

152/42/AEK-4/#7/AS 1.5

 

[RTL]

Thanks Dan, great stuff. CC sounds like a great resource, and I have come to love his posts. I for one really appreciate all of the hard work you and Ron and the others have put into this mod. You guys are tops in my book!

Brush, thanks for posting. Looks like I need to order some stuff from Sudco.

Fred T, keep it coming my man!

All, I will be attempting to document and publish a 'best of KDX jetting' around the RB mod to share with all. A year from now it will be nice to have such a document for new guys to the mod.

 

[Mac]

It would also be nice to know the jetting delta, this way people could see what your jetting was before and after the mod and know what kind of change to expect when they (me) have their carb modified. ;)

 

[70 marlin]

Here's the poop

99 220 fredette porting, stock slide. freddete 36mm carb, 152/42, cel center clip, AB lid off, fmf rev& TCII, stock reeds, I have a feeling I'm also heading towards a 40 or a 38 pilot? might also give the BEL needle a try? :think:

 

[Fred T]

Mac

Originally posted by Mac
It would also be nice to know the jetting delta, this way people could see what your jetting was before and after the mod and know what kind of change to expect when they (me) have their carb modified. ;)

Last season on my 33MM I was at 42 pilot, R1173 (stock needle) #2, 145 main. 148 main when cooler and A/S adjusted to taste.....er throttle response. IMHO the stock needle is lean in the midband 1/2 to 2/3 throttle and a CEL would have been better with the stock carb and #5 slide. I had the KG 30, holes in AB lid, boyesen 607 reeds and stock silencer, MX 2T 40:1 and 93 oct pump gas. Still preferred the clear goggles last season too with the Alpinestars Tech 6 boot and Green Jersey. :debil:

 

[canyncarvr]

Basic RB setup info

'experimental'? I don't think you'll find anyone that has done it that has any question but what it's something you HAVE to do (along with quite a long list of other 'stuff')


1. 40/152/CEK-4/#7TV w/KG35 (torque) 50-65º 25-3500'el.

Hits like a ton-o-bricks when the carb opens up (past the divider). RE: 'flat spot' noted by BRush with the AEG..No flat spot here! You'd best be holding on when the slide BRushes (ha) past the divider, cuz it's going to rip your arms off! Yes, a 'hit' is commonly what happens when the bike recovers from a preceeding flat spot..but that doesn't seem to be the case with this jetting sequence.

Seems pretty much unuseable for any sort of 'snot' riding. It is fun, though!!

2. 38/150/BEL-2/#6TV w/KG35 (torque..still) 35-50º 25-3500'el.

Much smoother..more linear (as dan sez). Great for more technical riding. Won't wear you out like the CEK, cuz it doesn't have its 'hit'. Has power that will easily pull the front end in 3rd gear. I'm not talking about a big wheelie thing going on, but come up on a hole or ditch, grab some throttle and the frontend will float over the obstruction. Smooth as silk. Just a bit of a throttle tweak over a water bar, and you are smoothly in the air with a gentle touchdown, ready for the next one. This happening at revs BELOW anything you'd commonly ride in without the mod.

The thing just purrs.

Both of these setups have been tried with/without a steahly weight. I prefer the weight largely due to much less stalling tendency on long downhills. It slows down the uptake of rev a tad. THAT ends up being MORE power, cuz there's less wheelspin happening.

3. 42/150/1173L-5/#7TV w/KG30(rev) 70-80ºs 35-7500'el. (summer riding)

No weight used with this one. Don't want to detract from the KG30 effect! Technical riding practically zip.point up here. Plug (B7ES) clean in every carb circuit..beautiful color every throttle position. This jet-set is a blast!!

Have run #2 with a DeltaForceII & Radvalve..the others with a Radvalve only. The DeltaForceII is a delightful improvement.

 

[RTL]

Good stuff CC. Thanks a ton.

 

[fishhead]

I used most of the above jetting with sucess but preferred the CEJ-3 with a 40 pilot and 152 main for most riding. I tend to shift up and use torque rather than rev it like a 125. The cej gives a little better torque up to 1/4 throttle or so. I found it to be just the ticket for tight woods riding, allowing me to hold a gear longer without shifting.

If you are running a cek-3 or 4 It would be worth a try to check out a ddk-3 or dck-3 needle. It should be cleaner in the bottom and give better torque at 1/2 throttle. clip position #2 would be worth a try also.

Jetting is pretty individualized, what works for one won't be ideal for someone elses style, so you see some pretty different packages here depending on riding conditions and style and rider ability. CEK, CEJ, BEL, DDK, DCK will all be good choices and for 25 bucks you can have em all.

The time invested in jetting provides a greater return on you performance dollar than any other change you can make. Take notes of temp and altitude as you try different things and you will be surprised how quickly you will get a handle on it.

 

[Fred T]

Fish
Thanks for the D series needle suggestions, you have described a little trouble I was having. I think I will try one out. Is CEj acceptable with #7 slide? Seems rich at 1/8-3/8 throttle.
FT

 

[canyncarvr]

Running the DDK and DCK thru JDs spreadsheet..they look about the same as the CEK on the bottom, slightly richer than the BEL (my current setup) on the bottom. So, FRED: The issue of the 'fat-on-the-bottom' you mention I wouldn't expect to get a whole lot better.

No, I haven't tried ANY 1º45' needles, so can't say anything from personal experience. I'm just looking at the numbers.

fishhead??

 

[fishhead]

Fred T
I preferred the #7 slide with the CEJ. under light loads it may be a bit rich but I found it pulled a taller gear better which helped traction. The general consensus favors the cek-3 or 4 but I found the cej gave max throttle response and avoided the hit or zap. It maximized the attributes of the divider plate mod for me.

CC
I found the slight difference at 0-1/4 throttle noticable but as you pointed out a ddl or dcl would be leaner. I found the B series taper to be a little weaker at 3/8 to 3/4 throttle than the c or d series and as a result the power would tend to fall off on a long hard pull. I suspect that your setup (220 and a torque pipe) may not be as sensitive to this as rev piped bikes. I think it would be interesting to test a dcl or ddl or a ddk dck set with your setup.

 

[jason]

I still have not had a chance to ride. I'm having a hell of a time with my local dealer getting my new excel rim right. When they trued it up it was offset to the spocket side!! Now they have the whole bike trying to figure out where they screwed up. I will hopefully get it back tomorrow and if it is not raining I will finally get to ride! I'm also needing to try out my mx-tech suspension. I can't wait to see how the mid-valve and rebound on the forks work on the trail.

I also have a question. How do you tell which slide (#5,#6,etc.) is in the carb? I am interested in trying some different set-ups but do not want to be stabbing in the dark.

RTL, I live in Henderson,abut 10 minutes south of Evansville,Ind.

 

[shr]

The rb carb has a slide that has been re-cut to #7

 

[canyncarvr]

Well...maybe it's been cut to a #7. Not all carbs are cut the same.

The answer to your question: The number '7' is 7mm as a measurement. Looking at your slide, on the bottom opposite the rounded side is an angle that sits right over the jet screen. The distance from the bottom to the top of that angle measured on the length axis is the cutaway of the slide. Most stock slides will have a number stamped in them where the control cable attaches. If the slide has been machined, you can measure the above distance to figger it yourself.

 

[shr]

Jason,

I do know for a fact, that the rb carb comes with a #7 slide for the KDX 200-220's.

If you look in the "D" shaped hole where the needle comes through, you will see the stock slide number stamped there (which was probably a "5").

Now if you look at the top of the slide where the cable enters the slide, you will notice a flat piece (it's the throttle stop and the idle screw touches it from the bottom)

If it's a rb carb mod slide, it will have a "G" stamped on it. The "G" is the seventh letter in the alphabet.

In simple terms the rb carb slides are re-cut stock #5's to a #7.

 

[canyncarvr]

shr:
Had no intent of impugning your information. My kdx was the first or second RB carb done for a stock ported 200. I'm familiar with how it's done.

Point is, if you know how to measure the cut, you can figure out the slide characteristic without wondering what any stamping (or lack of it) means.

And...if you happened to be talking about a large bodied PWK, an airstriker, a 38mm carb (whatever you wanna call it) or even someone's ktm..the measurement process and thus slide ID is the same.

And, yes...mr. black machines the slide on his RB modded kdxs generally to a 7mm cutaway.