Wr400 1999

I Have Just Brought A 1999 Wr400,idels Well With Choke,but After Taht,pops(backfires)and Cuts Out,alright When Hi Reving While Riding,but Soon As U Slow Down,pops And Wants To Cut Out,had It At The Work Shop Today,and The Valve Timing Was Out,but When Put Back To Norm,made A Horrible Knocking Sound(as If The Valves Were Hitting Someting) The Last Owner Did The Piston&rings In 04,could Something Have Happened Or Been Done Then?,at The Mo Its Been Set Back Were It Was,so At Least I Can Ride It,any Ideas Any 1?

ah.. spoken like a true 99 400 owner.....

when you say valve timing was out, do you mean it wasnt timed as per original? had the yz timing mod been done?.

and was the 'normal' setting as per original?

more info here


i wouldnt ride it if it is doing as you describe.

just trying to find out more details so that those who do have an idea what is wrong can help.

i think i would go throgh the real basic stuff again,drain fuel out, clean out carb, definitely put an new plug in, as these seem to like plugs (try iridium one).

when something sounds like its hitting valves, it possibly is.

it sort of sounds like a fuel thing though.

good luck

thanks 4 the reply,don't know much about them,had it in the shop,when they said the valve timing was out,i surpose they mean orig.went out 2 day on it,not popping as much but now won't always go back to ideling,stays reving high sometimes.don't know if it has been timed as a yz,been told by last owner,cam etc orig,did'nt tell me about the new piston though(as in what type)only thing i can tell is diff,is that it has a yzf tail pipe,has had new plug just put in,the reving staying high when riding,as in not going back to a lower idel,could that be the fuel?

dont want to sound smart, but you have undone the idle screw and checked in it?


lol,yeah checked that out,we adjusted the pilot screw last nite,and went riding today,did make a diff,and idels better then it has done,still pops every now and then,but not has much,i think its been set as the yz valve timing,but nothing else really done,wondering if it needs to be re jetted?,can your tell me if these bikes are normly abit rattly up top,or could it be the timing chain needs doing,i had a brand new klx300,which was rattly up top,and wwas told from the shop that they have a noisey cam train,thanks for your comments and help.cheers Rosco

poping and high idel is a sign of a worn or broken carbie slide, i would be looking at that before riding it again as its a comman fault with the 99 models, i know this as half the slide when through my top end and becasue of hopless mechs i am now in the middle of a total rebuild.. trust me for the sake of a few hour and a new slide and rubber(bout 200 all up) its worth it. MY wr was bullet proof, never missed a beat till all this shit and its been in the shop more than i have ridden it since it happened.....


cool,thanks for that,its in the shop now,getting them to check it over,i'll mention that to them,cheers Rosco

When I yz timed my 99, I had to rejet the bike much leaner. If it's back at WR specs, the jetting may be too lean now. Also, +1 on checking the carb slider.

no worries fella, i dont want to see someone else have to deal with the crap i have all casue of a broken slider, i wish some one would have warned me they were prone to going ... could have saved me heaps of time and money .... :ride:


hey thanks everyone for the advice,the shop found the inlet timing was way out,getting them to check,throttle slide as well,i hope this time when i get it back,all will be sweet,should have taken it to a yammy workshop in the first place

ok,just got it back,inlet and out let back 2 norm,carb checked,float adjusted,and set fuel mix screw,now does'nt seem to start as well,and still wants to pop,and cut out,all right with the higher revs still,but don't know what else 2 do, this bike is gonna make me broke,refase that,i am broke now,as i don't know enough to work on it myself

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