bk mod bogging still


12 replies to this topic
  • lawndude

Posted January 05, 2008 - 03:10 PM

#1

my 00 426 with full yosh and bigger air box bogged right off idle if the throttle was wacked, so i did the bk mod- even worse-i have tripple checked the timing and duration. i had stock main and pilot jets and the stock needle was in the fourth clip. I replaced the jets with a 168 and a 45. the pilot screw is set at 1 3/4 out. It runs great on top and mid, but will still fall on its face off idle. This bike has always started 1/2nd kick hot or cold. Any ideal I live in knoville tn riding in the 50's

  • lawndude

Posted January 05, 2008 - 04:16 PM

#2

put the 42 pilot back in and no change- riding tommorow please help. would the tps have anything to do with it?

  • cwimilan

Posted January 05, 2008 - 04:49 PM

#3

try a big pilot 50/55 i like a rich bottom especialy when cold.

  • Wes Woodin

Posted January 05, 2008 - 07:13 PM

#4

my 00 426 with full yosh and bigger air box bogged right off idle if the throttle was wacked, so i did the bk mod- even worse-i have tripple checked the timing and duration. i had stock main and pilot jets and the stock needle was in the fourth clip. I replaced the jets with a 168 and a 45. the pilot screw is set at 1 3/4 out. It runs great on top and mid, but will still fall on its face off idle. This bike has always started 1/2nd kick hot or cold. Any ideal I live in knoville tn riding in the 50's

I'd go with a powerbowl. I made my bike a new machine. It is an 08 but it did bog though. Powerbowl, 2.5 screws on the leak jet, 1.5 screws on the fuel screw, 52 pilot jet, and 168 on main. PM me if interested I'll put in touch with the right person.

  • lawndude

Posted January 05, 2008 - 08:14 PM

#5

thanks, i'll try a bigger pilot

  • lawndude

Posted January 06, 2008 - 04:05 PM

#6

i noticed after single track riding all day the throttle was hanging- maybe this will help?

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  • lawndude

Posted January 09, 2008 - 05:16 PM

#7

i put a bigger 52 pilot in and tried it, not really any noticeable difference. I do notice that the hot start must be pulled to start the bike once it is warm. with the 42 or 45 pilot i did not need the hot start. could it be the idle setting? if so what is the best way to set the idle speed - any ideas gray

  • KJ790

Posted January 09, 2008 - 05:32 PM

#8

Have you changed the fuel screw? This is the most obvious thing to me, and the first thing I would have tried before going through all the other work.

  • lawndude

Posted January 09, 2008 - 05:41 PM

#9

i have and adjustable one set to 1 3/4 out

  • grayracer513

Posted January 09, 2008 - 07:41 PM

#10

http://www.thumperfa.../jetting.htm#PJ

Get that 52 pilot out of there, too.

Be sure, when you say it bogs, that you're being realistic. The bike can not be expected to take a sudden snap of the throttle from idle to WOT without bogging, and if that's what you're after, you're after something that has no application in actual riding. Under what circumstance, when you're on the bike moving, and it's in close to the right gear, does it bog?

  • bg10459

Posted January 10, 2008 - 12:14 PM

#11

Have you had the carb slide plate out? Are you sure it isn't cracked?
I undestand that this bike is different than the 450's, but the only time I've heard of someone using bigger than a 48 PJ was because the slide plate was in backward or up-side-down. Also, the slide plates have been known to crack on the early WR's and YZ's.
Otherwise, I'd check everything in the pilot circuit. Be sure the fuel screw has the o-ring, washer and spring, and check that the hot start and choke aren't sticking.

  • lawndude

Posted January 10, 2008 - 07:43 PM

#12

thanks for everyone's help. i ended up taking the bk screw out and wire tied the linkage to the pump arm. I checked my pilot circuit before-hand and found that i neede a 40 pilot. there is no hesitation at all now.

-gray, this was no slight hesitation, when approaching logs or large rocks and trying to lift the front tire by wacking the throttle, the would just bwahhhh and die if not backed off-leaving me over the bars after i just hit the log.

now i have to rebuild the swingarm and linkage.

thanks again
brandon whitehead

  • BK

Posted February 07, 2008 - 07:39 PM

#13

there are times especially on the 00 bikes that the leak jet needed to be plugged with soldier to operate with enough pump pressure. This could have been the case in your bike.

BK





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