Stock Pipe jetting woes

TurboStew · Post by **TurboStew** » 10:05 pm Dec 15 2011

Thanks eveyone.

jbowens, thanks for the offer but I need to order some other stuff from Sudco anyway.

I'll try that DEL, although I believe it is out of the equation being WOT and all.

4vman1, let us know what you find, I am going to be ticked if I order a FMF woods pipe just to find out it goes ting, ting, ting and doesn't clean up my WOT problem, even if it makes more power!

4vman1 · Post by **4vman1** » 08:52 am Dec 16 2011

In the past I've had a similar experience with the then called FMF "Burley" pipe if anybody remembers them, they're the same as a gnarly woods (I think). The Pro Circuit platinum made a good size difference, but I wouldn't call it a torque pipe. My only experience with a PC II was on my 07 KTM250xcw and it felt almost identical to the aluminum foil stocker. I've been told that the PC II is identical to the PC I only with thicker metal, whereas fmf has two different shaped pipes.

TS, if I wasn't going to send my parts to RB in a couple of weeks, I'd already have the CEL and DEL needles to gave a shot.

G22inSC · Post by **G22inSC** » 08:58 am Dec 16 2011

CEL vs. DEL.

I never can remember. Which needle is the "big hit" one and which is the "smooth and tractable" needle? Need to write it down somewhere for future reference.

Post by **Julien D** » 10:31 am Dec 16 2011

CEL has a stronger mid range hit, the DEL is very smooth.

Post by **fuzzy** » 11:12 am Dec 16 2011

Others have you covered....the needle is where you should be looking.

The PCII I believe is a lower-midrange pipe vs the I which is more of a mid--rev (this would be consistent with stock XCW exhaust profile as well).

emulating one of those solenoid powerjet carbs that remove fuel on the topend by turnin on the solenoid above a certain rpm

Powerjets ADD fuel on the top end so you can run a proper main jet without fear of going lean on high load (sand), and long duration at WOT. They are sometimes TPS-solenoid activated.

TurboStew · Post by **TurboStew** » 11:21 pm Dec 16 2011

Powerjets ADD fuel on the top end so you can run a proper main jet without fear of going lean on high load (sand), and long duration at WOT. They are sometimes TPS-solenoid activated.

I beg to differ,

I believe you are referring to the dial-a-jet type of jetting addition, these are sometimes referred to as "Powerjets". They work by having a tube in the air stream like the OEM powerjet PWK carb, but they have no solenoid, they just suck it up on Bernoulli principle from the float bowl. If the float bowl fuel level were of the same height as the "powerjet" then it would fuel evenly all around, but because it has an inch or two of head, it fuels more at high air flows and less at low.

OEM PWK powerjets with the solenoid actually remove fuel at high RPM, they do this because OEMs have figured out they can get more overrev by leaning it out at high RPMs , as well as retarding timing.

diymirage · Post by **diymirage** » 11:51 pm Dec 16 2011

JBowens, i wouldnt mind taking that needle of your hands if you feel like getting rid of it
(im running a bills pipe on a otherwise stock bike)

if you think the needle will improve performance on my bike let me know and ill drop you an email

kdxmaniac · Post by **kdxmaniac** » 08:59 am Dec 17 2011

TurboStew wrote:
Powerjets ADD fuel on the top end so you can run a proper main jet without fear of going lean on high load (sand), and long duration at WOT. They are sometimes TPS-solenoid activated.
I beg to differ,

I believe you are referring to the dial-a-jet type of jetting addition, these are sometimes referred to as "Powerjets". They work by having a tube in the air stream like the OEM powerjet PWK carb, but they have no solenoid, they just suck it up on Bernoulli principle from the float bowl. If the float bowl fuel level were of the same height as the "powerjet" then it would fuel evenly all around, but because it has an inch or two of head, it fuels more at high air flows and less at low.

OEM PWK powerjets with the solenoid actually remove fuel at high RPM, they do this because OEMs have figured out they can get more overrev by leaning it out at high RPMs , as well as retarding timing.

sounds like alot of trouble to me? but of course......i dont run the baja 500 either.....you say you dont see how the needle has anything to do with wot? is the needle not in the main?

4vman1 · Post by **4vman1** » 06:50 pm Dec 17 2011

TWMOODY wrote:
scheckaet wrote:" I personally didn't feel a big bang for the buck with FMF Gnarley pipe"
then something must be off somewhere. Even with stock jetting the improvement was huge, even more after jetting it properly.
Gotta agree here something was off here.
The FMF was the largest improvement of any engine mod I did to my kdf.

Are you saying that the pipe was a bigger improvement than RB's head and carb mods? Or have you not been RB'd?

4vman1 · Post by **4vman1** » 08:56 am Dec 19 2011

Anybody? Is a FMF pipe a bigger improvement than RB's head and carb mods? They are roughly the same price, so inquiring minds would like to know. I need to have my Gnarly sent out and straightened anyways, but was going to get RB'd in a couple of weeks before I do that or just buy a new PCII.

TWMOODY · Post by **TWMOODY** » 01:11 pm Dec 19 2011

4vman1 wrote:Anybody? Is a FMF pipe a bigger improvement than RB's head and carb mods? They are roughly the same price, so inquiring minds would like to know. I need to have my Gnarly sent out and straightened anyways, but was going to get RB'd in a couple of weeks before I do that or just buy a new PCII.

TWMOODY · Post by **TWMOODY** » 01:12 pm Dec 19 2011

pipe comes first then R&B

4vman1 · Post by **4vman1** » 08:20 pm Dec 19 2011

OK, thanks. Has anybody on here had there carb and head modded by RB and still use the stock pipe? Will there still be a big improvement? I'm sorry guys, I just wasn't all that impressed with the FMF Gnarly's performance, at least not enough that I liked it more than the indestructible, quiet, and total underdog look of the stocker.

TWMOODY · Post by **TWMOODY** » 10:54 pm Dec 19 2011

The bike will still suck with the oe pipe on it no metter what you do.
When you put that FMF pipe on it and it don't scream you got other **** wrong.

TurboStew · Post by **TurboStew** » 11:06 pm Dec 19 2011

Okay all,

Well after pondering the problem a while, I started thinking ignition problem. I re-cleaned the carb, pulled the flywheel for electrical inspection, everything fine on the ohm meter, advanced the timing about 1 degree, and swapped the coil with my KDX250 (same part number, 9 Kohm vs 11 Kohm, both in spec). It ran much better, I jetted it to 148 and she runs pretty good. She still has a little loss in power if lugging and go WOT, runs stronger if you back off to 1/2 throttle until the rpms pickup a bit. Played with the pilot and clips, doesn't seem to make much difference. I did too much crap to know exactly what it was, my suspicions are the coil, I plan to swap the coil back in soon.

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Stock Pipe jetting woes