Taffy find this jetting stuff real hard to grasp.

I had a 2000 WR 400, until 3 months ago which had no air box

lid and a white bross E sieres with an FMF power bomb front

pipe, it ran great with no problems even choke worked well

one kick from cold would run on choke until warm no problems.

Real nice bike great fun easy to ride easy to start hot or cold.

Now lucky enough to have purchased one of yamaha europes last WR 400Fs, basically a 426 with 400 engine.

Disapointed with overall running, does not like running on choke bogs easy down low [slow corners], spits and stalls easy, runs genraly poor, only had this bike for approx 3 months, already used 2 new spark plugs.

When riden hard on a motor x track it all seems ok.

Both bikes YZ TIMED from new.

Please ask any questions about my bike that may help you to help me.

Sounds and reads like you know your jets.

P.S Do you ride eastern centre.

Many thanks cookeye newbie......


yes i rode my husey at the tunstall, hyde parker and borrowed a GG300 for the banks.

the bike is running very rich. even playing safe you should be good for 40PJ and 75 PAJ. aslo do the BK mod which reduces the APJ squirt.

the MJ can be about 165 and the needle will be ok if you come down on the main. if you don't come down on the main then drop the needle.

in other words do one or t'other!

i don't normally describe the jetting in 100 words but search for jetting Qs and it'll teach you quite a bit.


taffy thanks for your reply i WILL try all your suggestions

and then let you know how much better it is now tell me if you can what is a JR neadle for as i have one which came whith my full yamaha road kit allong with a155 main jet and some other jets wich have a small tube whith 8 small holes i have been digging in road kit box and also found 160 162 and a 172 170 main jet i cant find the JR neadle listed anywher here thanks cookeye


are you riding with choke on or off when cold? If riding with choke on you may be partialy fouling the plug causing running problems once warned up.

no choke whilst riding but thanks and have a good christmas cookeye

i don't know what you mean by a road kit?

i've never heard of a JR needle either. you've got me stumped.


Taffy this is a list of kit contents yamaha europe

large headlight indicators switchgear complete new wireing harness rear brake light switch hydrolic speedo with WR on its face another speedo cable auto of sidestand THINGMEBOB Stearing lock [JETS and NEADLE]

Flasher unit horn 2 fold away mirrors a nasty turned down tail pipe to rivit onto the o/e sillencer ,apair of strengtheners for the rear mudgaurd to hold the ugly number plate holder whith LARGE reflector, a sticker for the side stand which reads ATTENTION SIDE STAND WHITH AUTOMATIC RETURN and thers more a capacitor loads of different brakets and stuff for large light whith side light a small throtle stop THE BEST BIT is the cam cover breather to air box pipe complete whith clips and elbow for airbox boot my 2000 WR had this stuff fitted before it was boxed but boy did it cost. the yamaha part no for my neadle in the kit is as taken from its o/e packet 5jg 14916 jr



Taffy do you have a road bike


Taffy, i wanted to let you know i gave emn needle another try yesterday and bike runs great.thanks.i cant figure out why when i try almost same jet combination a few months ago bike ran like crap.only thing i really changed, was this time i used the emn needle instead of running 165mj ,45pj,emn needle 4th clip and fuelscrew 1 3\4 out.motor seems to rev a little faster and longer.powerband is more constant.i get all the power and rpms,but without the hard hit when using dvp needle 180mj and 48pj.with old jetting my bike's powerband hit more like 2-smoke i had to wait for bike to get on the it seems like its always in powerband more comtrollable,snappier throttle response.

the explanation of the road kit is great but i still can't help on ther JR needle.

freestyle. your low speed jetting is still very rich imho. the jetting in the winter goes up according to a lot of people here and so you're now running ok and it'll be crap again in the spring i should think.

therefore you're a hairs breadth away from running rich.

try dropping the needle one clip and put a 42 or even 40 PJ in with a 75PAJ.

you can back the whole thing off imho.

but each to his own.


Taffy,i havent ran pump gas since jetting change.i have about 15 gallons of cam2 110 octane ive been trying to use up.ill try changes you just suggested as soon as i finish off race gas.i would rather fine tune jetting running motor isnt stock,does that make much difference <ul type="square"> my wr400 motor specs [417cc big bore kit,stageI hotcams,minor porting and flowed head,p-38 and wbpromeg w/tapered headpipe.gearing 15\50

i usually ride above 4000ft.

er!! yep!!

it means if it ain't running right don't blame me!!! :D:)


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