Hey Taffy !


Put a new White Bros E-series on my ride a few weeks ago. At frist I used the recommended setting of 9 disks. This caused some backfiring when the throttle was released. I rode it around yesterday in the woods (Slowly to Moderate, cause my leg wouldn't take full bore) anyway, when it warmed up I was having a difficult time maintaining a low idle (which is where it was with the stock pipe) The fire extinguished it's self several times and I had to increase the idle set screw to keep it going.

Up until now My plugs have always been jet black after a run (Very Rich). Yesterday I added the entire pack of disks (12) before the ride. This almost completely stopped the backfire issue. I pulled the plug last night and it was a light grey...

I'm using the stock header with the exhaust. WB say's that I shouldn't have to change the jetting...but I'm not so sure.

**Just got off the phone with White Brothers...They told me to go with a 168 Main and Two Turns Out on the Air Screw**

I Guess I need to look for my manual and see what the Stock Main is for the US 99 WR 400.....

Your Recommendation?


Bonzai :)

[ November 05, 2001: Message edited by: YAMAKAZE ]


glad you're out already, great effort!

listen, i'm glad i don't live out mid-west because i fell off 6 times yesterday and half those times the bike was still running on it's side. i hit the deck in 3rd/4th and picked it up-still chugging away.

it will not stall. that i absolutely promise you. the problem is how do we get my jetting succesfully into your bike?

it's how to come down on the pilot circuit and the needle straight diameter WITHOUT scareing you.

it's no good me having this amazing jetting and you having a horrific misfire!

first of all the biggest change was the needle straight. i have over 90 tests logged carefully at only 3 or 4 a day usually.

the real breakthrough was the xxM needle. the thin diameter compared to the xxp was immediately noticeable. when i started the EKP it would rev it's balls off after 5 seconds and i'd be forced to rush back to the bike and turn the choke off. only to have it stall.

when i got the xxM needle the next time i started it the revs didn't move. three minutes later they hadn't moved. to be honest, that's the real answer. i'd tell everyone on this site tio get one but then someone will say that they live with mountain goats and the xxP needle is perfik!

EMM is superb. if you live very high maybe an xxN but at $10 why are we guessing, buy them both.

after that your needle clip position and PJ/PAJ combination need to come down very carefully.

it's all there on jetting Q's all you have to do is either print it off or write down each days testing with a column for MJ, MAJ, needle, clip, PJ, PAJ, PS. it will all become clear.

rucksack, water, 1/2lb bar of chocolate, no rad fanny flaps, one bolt in the seat, one in the tank, both engine clamps on the left, all your jets, tools, mobile, water, shagged out rear tyre, home made PS screwdriver, dictaphone. go, go, go!

if you want me to be even more specific on some point just ask.


I'm NOT Skeered !

Hit me with your best shot!

Altitude 450 to 1500ft

Isn't the 168 main standard in the 99 ?

Bonzai :)

give me what jets you've got in the box (of tricks) tell me your present settings and i'll post some idea's up.

i've had a mate call uptonight. just gone to YZ timing on a Y2K that has a white bros filter with all the discs in to keep it very quiet.

he put in the white bros 172MJ and he's very happy. now i would think that if i remember rightly i had a 168MJ std in mine with a 'D' needle. that would become a 165/162 with an 'E' series needle.

i reckon that the pipe is worth +8 to 10 on the MJ. that in turn means that the needle can come down.

so to be fitted in this order.....

EMMc4 needle

APJ disconnected

38/40PJ to go with a 75PAJ

little snap tests to see which reacts the best on the PS

by now you may trust me so you will try the 160MAJ

MJ down from 168 to 158

that should do it


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