Stopping intermitently at idle-driving me crazier

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June 9, 2009 at 5:33 am #96577

Bruce Curtis
Member

Ok here’s the drill.

2003 YZ250WR
Symptoms

Ocassionally when warm as you come to a low speed or pull up it doesn’t idle just stops dead, will also happen as you back the throttle off in low speed S/T, which has given me massive grief dropping into and trying to shoot back out of vert gullies.

Other things may or maynot be related
Spooges alot
Occassionally fuel runs out of carb overflow after hard charging over difficult terrian.

No I know what you’re all thinking… Fuel level/flooding, heres what I’ve done.

*2 new sets of reeds, currently running brand new force V3s’
*Compression is excellent, and always starts first kick even after stopping like this.
*Float is excellent, needle and seat look good.
*Fuel level is set .5 under factory
*Idle jet is 2 sizes under factory, still feels a bit rich though.
*Brand new Main and JD red needle.
*CDI has been moved to under the seat to eliminate coil interference.
*Air cleaner is rotated with 3 others, makes no difference.
*Fuel tank is whistle clean.
*Vent works on tank.
*Strong spark.
*Never fouls a plug, still change plugs regularly as matter of maintenance.
*Fresh fuel/older fuel just does it the same.

What am I missing?, doesn’t do it all the time, just enough to catch me out in difficult situations.

Bruce C.

June 9, 2009 at 7:47 am #138746

dennis da menace
Member

bruce, its simple…..

linkages:laugh: :laugh: :laugh:

sorry admin, couldnt help it

June 9, 2009 at 7:53 am #138756

Greg
Member

Blue I will copy and paste your story to fat head and ask his thoughts, then I will delete Menace’s crap before Admin fronts up

Will await F/H’s thought and paste it here

TB

June 9, 2009 at 8:53 am #138757

Dean
Member

Bruce this is a long shot but what is the exhaust packing like? My initial thoughts were the float level, I would go down another .5 of a mm as you only really need the max bowl level when WFT. Give it a try you never know

Ollie

June 9, 2009 at 9:44 am #138747

Nick Again
Member

would I be dumb to suggest the magnetic pic up? if it were an older bike i’d lean toward the low rev coil going..seeing thats out..perhaps theres an issue with the pick up for the electrics.? my .02c worth??? ( maybe H2o is in present in this area?)

June 9, 2009 at 11:05 am #138779

David
Member

Mate I once had a similar symptom and after hours and hours of teardowns a fractured reed cage block was the culprit, even though you have replaced petals in the block be sure to check the block itself, hope you find it:)

June 9, 2009 at 11:09 am #138799

glenn
Member

Ktmrat wrote:

Quote:

Mate I once had a similar symptom and after hours and hours of teardowns a fractured reed cage block was the culprit, even though you have replaced petals in the block be sure to check the block itself, hope you find it:)

Hey RAT what material are the blocks made out of??????

June 9, 2009 at 11:12 am #138800

David
Member

Most are metal and some are plastic, but I have seen both fracture, you only need 1 backfire from a flooded crankcase to do the damage, and deeds done.

June 9, 2009 at 12:47 pm #138801

Bruce Curtis
Member

Thanks lads

TB mucho appreciated, hopefully he’ll pinpoint it, tearing the few follicles I have left out over this one.

KTMrat the force V3s are in a new special cage that only they make, but it was my initial thoughts after the CDI/coil issue.

Ollie repacked the silencer thinking maybe it was the culprit, no diff.

Husky610 Maybe, I haven’t put a meter on it yet, but it starts so easy and a fat blue spark is evident on field testing, a possibility though.

Menace you’re a clown, but fellow Bozo institute graduate I totally understand, and I woulda done the same to you, unfortunately you’re from mechico so I’ll talk slowly for you in a colour you will understand, I have just greased my linkages, they are the funny things that give me a true rising rate rear suspension.

Boony the reeds are the closest thing we have to valves, and mine are a poly resin double VV arrangement with carbon fibre petals and they are a good thing to have in a smoker, but bad as in a stroker.

Keep it coming lads all input is fresh and with the combined brainpower of our brethren bulls we will fix it.

Bruce C.

June 9, 2009 at 12:51 pm #138822

glenn
Member

Ok heres a totally uneducated guess,,, is the carby butterfly and or slide doing wat they are meant to. Ie is it staying open when the old girl is in idle mode??????????

June 9, 2009 at 12:57 pm #138824

David
Member

Boony wrote:

Quote:

Ok heres a totally uneducated guess,,, is the carby butterfly and or slide doing wat they are meant to. Ie is it staying open when the old girl is in idle mode??????????

it would rise in revs if this was the case Boony ….more air/fuel mix equals more revs:)

June 9, 2009 at 1:01 pm #138825

Bruce Curtis
Member

Ta Boony but probably not, cause on a smoker with that issue you’ll get a massive amount of revs, loop out if moving or just take off into the scrub, (or accelerate at 3000000 gazelles hit the fence in your front yard on your heavily modded shmick cafe racer RZ350 in front of your best mate and wife as they laugh their heads off at you :blush: ), they don’t tend to bog, and this thing doesn’t bog, can loft to vert in the back yard off idle circuit at walking pace, is very very responsive. However that does give me an idea about the throttle position sensor attached to the carb, not all smokers have them, and it’s my first keihin with one so I don’t completely understand them yet so may have to do some internet digging on their exact function.

Bruce C.

edit- too slow Mr Rat beat me, bloody fast rodent he is too.

June 9, 2009 at 1:28 pm #138827

Dean
Member

yeh forgot about the TPS on your bike,from memory they put an xtra power jet of fuel into the carby when the throttle is cracked,there may be something there for ya bruce,good thinkingB)

Ollie

June 10, 2009 at 12:27 am #138758

Greg
Member

Trailboss wrote:

Quote:

Blue I will copy and paste your story to fat head and ask his thoughts, then I will delete Menace’s crap before Admin fronts up

Will await F/H’s thought and paste it here

TB

Reply from Fathead

Ok my little brother NN

Firstly V force 3 always make it richer through the bottom to mid, he has
gone 2 pilots smaller than standard already, but may need to lean it more. I
need to know the air/fuel screw turns, what size pilot. The float needle
might look good but thats not to say that it isn’t sealing 100% of the time.
We do get bikes where the needle looks good, we lower the float level & it
still leaks.
One very random thing is the crank seal on the gearbox side. Is it leaking &
sucking gearbox oil into the bottom end. It’s not very common but it can
happen.
How many k’s has the bike done? Has it had any top end or bottom end
repairs? Has this problem just started or is it on going from new?

On another note. We need to service your shock, it hasn’t been done & I
think it will be pretty shitty. When you’ve got a free day come on down to
Fatbat land, we’ll do a Shock Service article & eat some hot english
mustard.

Oh also nearly forgot, good luck at Port Macquarie pny express this weekend.
I’d love to come up & support you but the work never stops.

Fat Head, your big Brother

Thanks Fathead

June 10, 2009 at 12:47 am #138826

glenn
Member

Ktmrat wrote:

Quote:

Boony wrote:

Quote:

Ok heres a totally uneducated guess,,, is the carby butterfly and or slide doing wat they are meant to. Ie is it staying open when the old girl is in idle mode??????????

it would rise in revs if this was the case Boony ….more air/fuel mix equals more revs:) [/qu

What I meant was, is the slide staying at the correct setting or is it closing right up which in turns starves the engine of fuel causing premature shut down, but the bike will fire straight back up when kicked again…?????????
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Stopping intermitently at idle-driving me crazier