bloody thing

I posted a couple of weeks ago with a big backfire. Did the new plug and drained the bowl and it worked and away i went. I couldn't get a cr8e plug and got a cr9e instead. guy at bike shop said it was ok. a couple of days later it was hard to start and was 'fluffing', not quite a miss but a little stutter at low revs. once it was going it was right. then it has gotten harder to start and now i cant start it at all, doesn't even sound like going. has backfired once again, a slightly muffled farty type bang. when i tried with the hot start on it sounded like it wanted to go and the headlight came on for just a second ( meaning it must have at least fired) but now nothing.

my foot is hurting and I'm unfit.

any suggestions.

p.s. plug was quite black, not much stuff on it ( seeing it has only gone for like 15 minutes)

Sorry mate I cant help but will greatfull when somebody does cos it sounds just like mine-it was backfiring on start up and when decelerating, and has gotten harder and harder to start. I think my battery must be flat now though (I hope) because now the starter just 'ticks' and I have to kick it....

I have decided to give it a once over and have ordered a JD jetting kit, will change the plug and see what happens?

Sounds like someone needs to check their valve clearence.

Bluebike put the right plug in as different plugs will operate best at different temp's.

For both of you, I would give a carb a thorough going-thru. My bike did the same thing. When I bought it ('99 WR400), it was jetted for winter riding, which was way too fat for the warming temps. I went thru my carb and found it had a bigger main, pilot, and the fuel mixture screw was twice as far out as stock. The bike would run for a bit, but when I shut 'er down, she wouldn't restart w/o a clean, dry plug.

Also, the higher the number with the NGK plug, the colder it is. Normally, this would not hurt, but if you are running a bit (or a lot) rich, you need a hotter plug, not a colder one. For a wet or dark plug, get a hotter plug, in this case the stock 8.

Also, valve clearance can affect starting. Maybe a check is in order.

thanks Greg. I just had it done to YZ timing and the mechanic who did it said my valves were in spec. that was only done about 40km ago.

Let the mechanic fix it.(if he/she did the timing)

Yz timing won't work with 05 Wr450, due to decomp pin on ex cam, have him put back to wr timing.

Yz timing won't work with 05 Wr450, due to decomp pin on ex cam, have him put back to wr timing.

Curious on decomp pin on exhaust cam. How does that work? Open on exhaust valve early or later???

Thanks, Jeff

The pin opens one of the ex valves and once the engine fires the centrifugal force allows the pin to retract.

Not sure of the details exactly, someone on here should know, but my stupid mechanic thought he would do me a favor and switch the timing to YZ, while doing the valves, I came to pick it up and the thing wouldn't start. :)

Anyhow we figured it out by calling around, its a centrifical pin, so when its running it pulls in and no decompression. When it not running the pin is out and aids in starting. You switch timing with the ex cam and therefore it throws off the the timing of the pin and no starty :)

Thats how I understood it anyway??

Must replace Ex Cam to go to YZ timing.

Yz timing won't work with 05 Wr450, due to decomp pin on ex cam, have him put back to wr timing.

Actually It is possible to re-time the 05 exhaust cam, however one must press off the sprocket to do so. :)

Let the mechanic fix it.(if he/she did the timing)

yeah, i think you're right. Given my mechanical expertise i'll take the 'do it once do it right option' and get him to have a look.

I'll let you know how I go.

Thanks again everyone.

ps just bought another pw80 for my youngest son,(4y/o) can't wait to blow him off Marcus style.

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