stalling while pinned, 00 WR400

[Dean]

My 00' WR stalls once per ride after it's been running for about an hour. It almost always occurs while the throttle is nearly pinned. It happened last going up a dune in 3rd gear pinned. It takes about 20 minutes to get running again. If I kill it after that it will start right up. Has anyone run into this problem before. I only took about 10 mm off the throttle stop and have the yzf cam timing. No baffle or airbox cover.

Any suggestions would be greatly appreciated.

[Taffy]

your plug has had enough. if you've had it a while, change it.

better still try a harder plug (most people have stopped using the term cold or hot) so go to a '9'.

Taffy

[Dean]

It has been awhile since I put in a new plug. I'll give the 9 a try, Thanks

[Ron_in_SoCal]

Could it be the one-way valve in the fuel tank vent tube???

[Guest Guest]

I agree with Ron. Try droping the main jet cap on the bottom of the float bowl the next time it happens to see if any gas in the float bowl.

[MN_Kevin]

Do yourself a favor, dump that stupid check (one-way) valve. You will have rid yourself of a potential problem (pressurizing the gas tank). And yes, it has happened to several guys so far.

------------------

'99 WZ with all YZ mods, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action, OEM YZ tank and IMS seat.

[Hick]

That’s good advice, but it may be easier to open the drain valve right next to it that feeds a carb vent (or in this case drain) hose. It is a small allen-head bolt, and a half turn is plenty to open it.

[Taffy]

it's the plug!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Taffy

[This message has been edited by Taffy (edited 03-16-2001).]

[Marty]

So what are you trying to say Taffy? Im not getting you. JK ?

[Taffy]

the spark is 'blown out' like a candle when put under extreme pressure. that's full load, uphill, third gear, sand, towing a lorry, headwind etc etc.

it can be an old plug, it can be that it's oldish & the spark can't jump the ever widening gap at the tip.

the difference between a hard & soft plug is the exposure of the centre of the plug. if it's a soft, plug, porcelain, tip & earth post are all hanging out in the wind. this means they get hotter quicker.

with a hard plug everything is slightly lower inside the thread so to speak. so as to avoid the heat of the chamber.

that's as i recall it anyway. i just recognise the symptoms.

over on the YZ side i tried to help many plug foulers last year by asking them to go to a softer plug. it's now being recommended regularly by riders. that was hard work. i find americans a lot more gullible & therefore resistant to trying things. just my opinion & no offence meant.

a soft or hard plug isn't the answer 95% of the time. the answer is to use the plug that keeps your bike chugging away WHILST you get the jetting RIGHT.

so our friend MAY have an old plug or a lean mixture necessatating a harder plug.

whilst practising for the Manx GP in the Isle of Man my mechanic friend had been so cold at 5am that he'd pulled a cooking plug out of the front cylinder of my Duke & put a racing one in it's place. he then pulled the other cooker out of the rear & put the OTHER COOKER back in!

when i came in with a misfire we stood there arguing the merits of my jetting with some 60 year old twit!

when he'd gone someone told me it was Hugh Anderson (NZ) 4 times RR world champion on suzuki 50's & 125's in the sixties!

anything you say hugh!!!

Taffy

[Dean]

I bougt the new harder plug today and I'm putting it in a little later. I'm also taking out the vent one-way valve at the same time.

Thanks to everyone for their good suggestions.

Dean ?