RB carb tweak (it's 2-2-2 carbs in one!)

canyncarvr

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#1
I'll keep this short. Email me if you want further particulars.

This has proven true on three different bikes, two different brands, three riders. It costs you nothing to try it.

There appear to be two 'sweet spots' for air screw adjustment on RB carbs. That's what it's been tried on..I don't know about the oem pwk.

You RB'rs....try your airscrew out further than you'd think reasonable. If you're normally set to (example) 1 1/4 for best throttle response, try something out in the 2 1/4-2 1/2 range.

This considers your jetting to be close in the first place.

You get a different power delivery altogether! Improved pull from very low revs. More throttle gives you more 'go' without 'loop-it' tendencys. Where you'd be downshifting before, more twist works..where more twist before would get you a bog with little-to-no pull.

You'll find mid-throttle response for 3rd gear to be much better, too. You can short shift to 3rd and still have plenty of pull. That's always been a problem with the kdx, cuz 3rd is kinda 'far away' from second ratio-wise.

You can still loft the front any time you want..but it's a controlled pick-up. You can change the amount of loft easily with the throttle.

The 'far out' setting is great for single track..the 'normal' setting better for more open riding (imo).

Keep in mind that the rb modified carb has a useful pilot circuit compared to the oem pwk. Little air screw changes can make a huge difference! Don't be yanking the screw around 1/4 turn at a time, or you'll miss the whole thing! ;)

Give it a shot! I'll bet you'll be surprised!!
 

Jim Crenca

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#2
What he said!
Actualy, Brad and I have been sharing notes on this since he turned me on to it.
In a nutshell; hills that I couldn't climb from a dead start in sceond gear at 1 turn out of AS (my best "performance" setting), I can easily climb (with some engine bog), at 2 TURNS OUT
When you blast up to a jump at speed in 4th gear just off idle, snapping throttle at 2 turns out launcehes bike gently; at 1 turn out, bike jumps much farther and more agressive
The above have been very repeatable results for me; at approx. 1 turn farther out than your usual best "agressive" acceleration setting, lies a gentle, "won't toss you off the back on a slick, root infested, steep hill" setting that will allow for a better tight woods riding that is less tiring, IMO.
 

KelvinKDX

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#3
I gotta pay more attention to the finer points with the air screw.  You guys seem to be having just too much fun!  :)
 
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#4
Thought I'd bump this up

Someone somewhere was asking about this thread yesturday
 
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#5
WoW!!

Ron sent my carb with the a/s 7/8 out

Today was the first day I adjusted it, I stopped on the trail and adjusted it 1 1/2 turns out

Started the bike and let out the clutch a little when I discovered I must not be in first gear, so I feathered the clutch a little and she took right off. I sped down the trail about a fifty yards when I noticed I was still gaining speed and I still had not needed to shift, so I started wondering..... :think: what fricking gear am I in?

So I started downshifting, Once, Twice and finally a Third time! :eek:

Started from a dead stop on flat ground in FOURTH gear! :yeehaw:


Tried some twisty uphill trails I used to always have to shift up and down from first and second to make it through at high rpm's.

Now I can pretty much ride it in third and fourth, low rpm's and lots of traction. SWEET

Throttle response is nice and smooth without that hard hit it has at 7/8 out
Not saying I don't like that hard hit but today was just too snotty in that Quartz Creek red clay.