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My carbi is a mess wheres a good starting point of tuneing

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Well my story is a long one lol here it is

A few months ago brought this bike 03 WR250F it had a slight miss when i brought it i fugured that i would be able to tune it out (WRONG). After makeing the mix richer it would be ok, 3 weeks down the track it would be missng and craping on again. This happend a few times and i started to think this is really not correct, so i explored a bit further and found the valves wer absoluly stuffed out.

I just finished rebuilding the head everything is to spec i have checked 5 times, the drama now is, it is now missing and coughing more than ever. I am now looking at the carbi , the carbi is a mess. due to me trying to tune the untunable

this is what i have

03 wr250f

full staintune system

stage1 YZ250F hot cams

stainless valves

high rev valve springs

Carbi

Main jet: 180

Pilot Jet: 45

Fuel screw (turns out): 2

Needle model/Clip position: OBEKR 4th

leak jet: 90 ( only getting .26sec of AP squirt duration)

Temp: 15~40 degrees

Altitude where i ride:0~1500 feet

Spark plug: is balck and sooty,the porcalin is a really dark brown neally black

i dont even know if wats happening is the carbies fult

any advice is good advice

cheers to all

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Jetting looks pretty good. Could try the clip on position 3 from the flat/top. Unless all you ride is fast MX, you might want to try a smaller leak jet, perhaps even a 40 or 45.

Did you try a fresh plug?

Did you confirm all electrical connections are sound and no wires are chafed?

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yes new plug

the wireing is a mess, so i will strip it down and start that from scatch i think

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unpluging the TPS made no diferance i also pulled out the multi meter and all TPS readings are in spec

also a funny update

I jumped on yesterday whent down the road and it was running supreme. I pulled the front wheel up in the air, and the split second the front wheel touched the ground (with a bit of head shake) it started missing realy bad again , so i started comeing straight home, just around the corner form my house it died in the ass and would not go, i got it home pulled the tank off litualy touched a couple of wires and it fired up againe but with the MISS still present.

I whent through all the wireing this arvo, I tieded up wat i could and did not find any dramas , i didnt put the multi meter on any of the diodes or watever though ( i dont now which one do wat yet lol). after all this there was no diferance.

NOTE miss is after 1/4 throtel

would i be advised to post this in a diferant forum lol

chers

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Read your shop manual, test the ignition pulser (spark timing sensor) and source coils.

looked through the manual and searched around abit , i have not found much info on either of these specificaly is there diferant names for these

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LOL, yes, Yamaha named them the pickup coil and signal coil.

I have a feeling your issue is with the pickup coil. Typically, as these get ready to fail, the problem manifests itself as a high rpm miss first.

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pick up coil is in spec reading :287 ohms resistance

Ac magneto im not sure i am borrowing a better multi meter with more decimal places tomorow night

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William my father told me to hold the ignition coil inslator beside the head and wind it over, sparks came out the insulator with no spark plug in, so i put a spark plug in and it would spark across to the head , but when i slowly moved the spark plug away from the head it would then spark out the insulator again. (By insulator i mean the plastic shaft (the mid section) )

If this means its stuffed then alot could be answerd for , except the question "why did it run great all day monday until i puled the when up in the air "

Do you have any thoughts on this

I will test the AC magneto in a couple of hours after work

really really apreciate all this help

thankyou

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just thought i would let you guys know , i took it to a good bike shop and 3 weeks later they tell me its the CDI and they have tested a new one in it ,

So thankyou verry much for your helps

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