Yz 250 help !!

jimmygraft
I have a 2001 yz 250.

It's starting up fine yesterday but as soon as i touched the throttle it dies straight away... today it didn't even start.

I have taken the carb apart and cleaned all bits as i thought it would be a fuel problem.

Now here's the part im embarrassed about, the day I was riding there was a moment where i pinned it too long in second and the bike just cut out and died after, it started back up again straight after but kept dying when i gave it throttle... also oil started leaking from my exhaust - ( black oil )

I replaced spark plug aswell.


What should I be checking replacing next to try and troubleshoot this issue ?
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TrailDigger 5/20/2018 3:30pm
5/20/2018 3:30pm
I would start with electrical components and in the manual, there are values for resistance for each part. Maybe the spark is breaking down under load and something finally went during your long wfo run.

Did you touch or adjust the TPS?
jimmygraft 5/20/2018 3:44pm
5/20/2018 3:44pm


I thought TPS was for bikes with sensers and computers? Please exscuse my novice ignorance if im wrong. 


Also where would you suggest instant with electrics? It's probably the only part of the bike im least knowledgeable with. 


Thanks mate. 

jimmygraft 5/20/2018 3:45pm
5/20/2018 3:45pm
Where woukd you suggest I start **** with electrics ( fu£¥$€#; auto correct )
Paw Paw 271
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Paw Paw 271 5/20/2018 4:00pm
5/20/2018 4:00pm
Questions:
1. How old is the fuel mix?
2. What ratio?
3. Do you have a Bright Blue spark at the plug?
4. How long has the bike set between rides?
5. Have you checked the coil OHMs readings?
6. How long from the last rebuild?
7. Have you pulled the exhaust to look at the piston?

Paw Paw

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project racer 5/20/2018 4:05pm
5/20/2018 4:05pm
May have suffered a light piston seizure after the Bonneville run. Now low on compression.
jimmygraft 5/20/2018 4:27pm
5/20/2018 4:27pm
Paw paw 271

1. Replaced fuel today
2. 32/1 but you have just reminded me, my friend borrowed it the ride before and put 32ml of oil / 1000ml of petrol... would that have an impact ?
3.havent checked man.
4.around 2 weeks.
5.No, i dont know what that is.
6.around 15 riding hours.
7. No, i took the head of and all looked in order.

Again, please exscuse me, im really new to fixing my own bike. I know it must be frustrating trying to advise and help someone that only has little knowledge on bikes.
jimmygraft 5/20/2018 4:32pm
5/20/2018 4:32pm
Paw Paw 271 wrote:
Questions: 1. How old is the fuel mix? 2. What ratio? 3. Do you have a Bright Blue spark at the plug? 4. How long has...
Questions:
1. How old is the fuel mix?
2. What ratio?
3. Do you have a Bright Blue spark at the plug?
4. How long has the bike set between rides?
5. Have you checked the coil OHMs readings?
6. How long from the last rebuild?
7. Have you pulled the exhaust to look at the piston?

Paw Paw
Paw paw 271

1. Replaced fuel today
2. 32/1 but you have just reminded me, my friend borrowed it the ride before and put 32ml of oil / 1000ml of petrol... would that have an impact ?
3.havent checked man.
4.around 2 weeks.
5.No, i dont know what that is.
6.around 15 riding hours.
7. No, i took the head of and all looked in order.

Again, please exscuse me, im really new to fixing my own bike. I know it must be frustrating trying to advise and help someone that only has little knowledge on bikes.

Paw Paw 271
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Paw Paw 271 5/20/2018 6:05pm
5/20/2018 6:05pm
Again....How old was the fuel that was used when you started having this problem?
Also, pull the exhaust and post a photo of what the piston looks like in the exhaust port. It will tell us a lot.
Also, check to see if you have spark at the plug.

Paw Paw
jimmygraft 5/22/2018 1:59am
5/22/2018 1:59am
Paw Paw 271 wrote:
Again....How old was the fuel that was used when you started having this problem? Also, pull the exhaust and post a photo of what the piston...
Again....How old was the fuel that was used when you started having this problem?
Also, pull the exhaust and post a photo of what the piston looks like in the exhaust port. It will tell us a lot.
Also, check to see if you have spark at the plug.

Paw Paw
Right buddy,

Pulled off the head today and the rubber ring had split and im guessing was letting a little coolant in which was stopping it start.

New one installed, starts firat kick but idles high. After giving it the slightest throttle it dies on me. After taking the carb apart again, I've noticed the main jet is bent from the bottom of the thread and down. Bent in such a way that trying to get it out it snapped leaving the thread in the carb !!

A new carb is £40 which im more than fine with paying. The question is, will this solve the issue of it dying when i throttle it ?

And to answer your questions - the fuel has always been new and never sat with old fuel - piston looks fine, a lot better than I expected actually - I didn't see sparks at the plug but it shocked me when i kicked it !?
jimmygraft 5/22/2018 2:00am
5/22/2018 2:00am
Paw Paw 271 wrote:
Again....How old was the fuel that was used when you started having this problem? Also, pull the exhaust and post a photo of what the piston...
Again....How old was the fuel that was used when you started having this problem?
Also, pull the exhaust and post a photo of what the piston looks like in the exhaust port. It will tell us a lot.
Also, check to see if you have spark at the plug.

Paw Paw
Owe, also fuel was pissing from the overflow on carb when started.
mattyhamz2
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mattyhamz2 5/22/2018 8:58am
5/22/2018 8:58am
Paw Paw 271 wrote:
Again....How old was the fuel that was used when you started having this problem? Also, pull the exhaust and post a photo of what the piston...
Again....How old was the fuel that was used when you started having this problem?
Also, pull the exhaust and post a photo of what the piston looks like in the exhaust port. It will tell us a lot.
Also, check to see if you have spark at the plug.

Paw Paw
jimmygraft wrote:
Owe, also fuel was pissing from the overflow on carb when started.
Float needle is sticking or floats are not adjusted properly.
kpersonius264
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kpersonius264 5/22/2018 2:39pm
5/22/2018 2:39pm
Paw Paw 271 wrote:
Again....How old was the fuel that was used when you started having this problem? Also, pull the exhaust and post a photo of what the piston...
Again....How old was the fuel that was used when you started having this problem?
Also, pull the exhaust and post a photo of what the piston looks like in the exhaust port. It will tell us a lot.
Also, check to see if you have spark at the plug.

Paw Paw
jimmygraft wrote:
Right buddy, Pulled off the head today and the rubber ring had split and im guessing was letting a little coolant in which was stopping it...
Right buddy,

Pulled off the head today and the rubber ring had split and im guessing was letting a little coolant in which was stopping it start.

New one installed, starts firat kick but idles high. After giving it the slightest throttle it dies on me. After taking the carb apart again, I've noticed the main jet is bent from the bottom of the thread and down. Bent in such a way that trying to get it out it snapped leaving the thread in the carb !!

A new carb is £40 which im more than fine with paying. The question is, will this solve the issue of it dying when i throttle it ?

And to answer your questions - the fuel has always been new and never sat with old fuel - piston looks fine, a lot better than I expected actually - I didn't see sparks at the plug but it shocked me when i kicked it !?
You have to touch the end of the spark plug to steel.

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