Posted October 16, 2001 - 11:10 AM
Altitude <1000', Temps 60's F.
1. Start at clip #4?
2. Do I remove the MAJ completely or leave in the stock?
3. Approximate # of turns on pilot screw?
4. Do I dare do the BK mod at the same time or wait until I have it running good first?
BTW, that YZ pipe is awesome. Actually a quieter (or at least less annoying) exhaust note at idle and slightly above. So neighborhood rides are back....short shifting of course. Thanks.
Posted October 16, 2001 - 06:49 PM
Pilot screw @ 1.5 turns
WR Timed, Lid on but opened up(3 1" holes down center of lid)Grey wire cut, Baffle out and finally did BK last week. Rode this weekend at Victor Falls(Bonney Lake) and it ran terrible? Had to back fuel screw down to .25 turn to lose the 0-1/4 throttle bog from hell and the bike idled fine with screw completely closed? Any suggestions? Bike was running phenomenal at Naches and Auburn West Hill by Hinshaws before I did the BK and I'm pretty sure the AP is adjusted correctly(squirt starts just after slide raises, does not hit slide at all, and lasts approx. .3-.5 secs.). Seems like I would need to richen instead of leaning out at Victor Falls? Now I'm really ? Any help would be greatly appreciated.
Y2K WR400FM,Answer top tree w/Accu-Trax clamp,Pro-Tapers(CR-Hi w/ EE handguards),Devol Rad. & frame guards, Guts tall soft foam w/ ballistic cover, 14/52 w/DID VM X-Ring, Kouba-T,Michelin M-12's ft.& rr.,12 oz. flywheel weight, Zip-Ty Racing Link & Shark Fin(plus everythhing else cool that Ty offers), Cycra front rotor guard and T.M. Designworks Chain guide, buffer & chain wheels. Street legal except for the non-"DOT" tires.
Posted October 16, 2001 - 07:07 PM
#45 pilot and ~2 turns (out to richen/in to lean)
Make sure the carb boot is tight and sealing. All the other bikes using Dxx needles have a #175 main, then there's the WR which comes with the restrictors that get removed.
Posted October 17, 2001 - 07:58 AM
Posted October 17, 2001 - 12:02 PM
Apparently, you can see "the squirt" by looking thru the airbox opening on the carb? I'm assuming that the jet needle raises and lowers (based on clip position) into the tube that attaches to the main jet...with fuel flowing through the main jet/tube past the needle jet...but after that, where does the fuel go? What exactly is this "slide" that people are referring to that the timing screw on the accelerator pump adjusts?
Clueless in Colorado
Posted October 17, 2001 - 12:20 PM
Posted October 17, 2001 - 01:03 PM
You are not totally clueless, after all, you know where to go for answers
Your explanation of the main jet and needle interaction is pretty good IMO, after the fuel flows through the main and past the needle it is inside the carb venturi and on its way into the motor.
But this has nothing to do with the accelerator pump, which is what the BK mod involves.
The slide is simply the carb slide, and also doesn’t really relate to the accelerator pump except that opening the slide (twisting the throttle) is what starts the accelerator pump via a mechanism on the slide pulley (part where the throttle cables attach).
So, twist the throttle, you lift the slide and allow the accelerator pump to begin its operation. On ’00 and newer YZ/WR thumpers there is a screw on this mechanism where you can adjust the operation or “timing” of the accelerator pump relative to the slide. This matters for obvious reasons, not the least of which is that the jet or orifice that delivers the fuel from the pump into the carb is behind the slide, so that if the fuel is spraying too soon it will just hit the slide and make a puddle, doing you no good.
The BK mod allows you to limit the stroke of the accelerator pump, or the duration of the squirt and amount of fuel delivered every time the throttle is opened and the pump operates. Since the nozzle or jet that the pump squirts fuel through is behind the slide, looking into the carb from the air box side (with the air box off, of course) is a good way to see “the squirt.”
BTW, I was just talking to a buddy of mine who lives in Denver, and apparently Excel Yamaha there has changed the pump diaphragm in a few guys’ carbs. That is just a different, unadjustable way of doing what the BK mod does.
Posted October 17, 2001 - 02:43 PM
BK mod .4-.5 sec.
Dudes, I'm bummed. I just went through all this crap with my Husaberg...don't know if I can take it with this one!!
[This message has been edited by Scott in KC (edited October 17, 2001).]
Posted October 17, 2001 - 02:54 PM
This is really odd. The pilot screw should not need 2 turns out, sounds way too rich. Is there an air leak? TPS connected? Hot start closed?
You have YZ426 jetting basically other than a bigger pilot jet. It should run like a YZ??
Posted October 17, 2001 - 05:43 PM
James, at this setting, even if I'm off a clip position, or 2 numbers on a jet, is that enough to be causing something like this?? I mean could I be too rich on the needle & main, rich enough to cause this?
Posted October 17, 2001 - 06:08 PM
The idle speed should not hang at all with a #48 and 1 turn out, 1 1/4 max. This is usually an indication of a lean problem. Clip position #4 would be a possible step, should also work very well. Something is not right. Tank full? pinched fuel line? Was the stock pilot a 42 and how far out was the pilot screw before?
[This message has been edited by James Dean (edited October 17, 2001).]
Posted October 17, 2001 - 06:43 PM
Whats the best way to get to the needle without totally removing the carb again? Take the tank off?
Posted October 17, 2001 - 11:37 PM
your buddies on their wr426's are all running jetting below the 400's i would think due to the greater volume of air that the engine pulls through.
they're running EMP clip 2 which is 2.5 drop of the needle. THAT'S A HUGE DIFFERENCE.
they're running 40 or 42 PJ's and most definately not 48's.
i would suggest you drop the needle one clip and if you note an improvement (ie less misfiring) then i'm sure you'll be only too pleased to do the same again and then a third time if your doing well!
as far as your pilot circuit goes i would drop straight from 48 to 42, stay with the 100PAJ and put the PS out to 1.5 turns.
do little snap wheelie tests with the PS going + & - .5 turn. this takes minutes with the correct screw driver.
quickest way to work on carb?
no fanny flaps on the rad
one bolt on the tank
one bolt on the seat
both engine plates on the left
FOR THE NEEDLE
twist it having undone the front and back screwa so you can open the top. to grab the needle, snap the throttle open hard and catch it with your fingers! (quite funny to watch).
UNDERNEATH AND ENTRANCE FACE
pull carb outside the frame. BTW, i have no APJ housing cover at all. so it's a doddle.
[This message has been edited by Taffy (edited October 18, 2001).]
Posted October 18, 2001 - 01:39 AM
The weird thing is, that it does feel lean in the mid-range to my untrained wrist (I had gone through some similar jetting issues on my previous Husaberg), which is harder to believe considering how rich it is now.
Thanks for everyones help here, I know jetting is not easy, just hoping for a miracle out of the box.
Posted October 18, 2001 - 01:48 AM
woody is on an EMP-c2 with 42PJ
slashman is the same (45PJ)
stefe's needle is up two and he's unhappy as well!(42PJ)
Posted October 18, 2001 - 02:39 AM
Posted October 18, 2001 - 03:10 AM
Posted October 18, 2001 - 04:03 AM
Now I just need to find a way to convince my wife that working on my bike in the garage this weekend is a good idea!
Posted October 18, 2001 - 04:41 AM