2013 kx250f cuts out when hot

flabdog
Posts
13
Joined
3/12/2017
Location
GB
Hi all

Got a kxf250 2013 which we've had for about 4 months. About 6 weeks ago it started bogging down or just cutting out. Its been to Kawasaki dealer who plugged it in and the diagnostic showed 19 faults with the air pressure sensor. I was replaced and we took the bike out for a test and after 5 mins it started bogging down and cutting out again. we were leaving the bike to cool down and on the following rides out after 5 mins or so the same thing would happen again. could it be an issue when the bike is upto running temperature maybe ?????????

Back to the dealers it went and this time the stator was removed and sent away for test. All was fine until they used an heat gun to warm it up and it was showing as faulty when hot. That was "fixed" and we got the bike back again only for the same thing to happen again after 5 mins or so.

Since the last dealer visit the stator has been rewound, a new coil fitted and the bike ran while the engine temp sensor was disconnected and the bike is still the same.

Any ideas where to look now please guys ?
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speed_racer
Posts
353
Joined
7/29/2016
Location
Aiea, HI, USA
4/1/2017 3:40pm
It is very hard to figure out these type of problems over a computer, true diagnostics require a step by step process.

3 parts replaced or fixed. New or rewound stator, coil and air pressure sensor. None of these actually fixed the symptom of it bogging or cutting out.

It does run good for 5 minutes.
I am not sure what is wrong. I wouldn't worry about the fuel pump or fuel pressure if it runs good for 5 minutes.
Do not let anyone sell you an electrical part unless they promise a full refund if it does not fix it!
While it was bogging I would loosen the fuel cap and see if the cap wasn't venting causing vapor lock.
If it still died with the cap off I would rule out vapor lock and cool the engine with a big fan, see if it starts when it's ice cold. If it starts up cold I might think I have some weird heat related problem killing it when hot, like a small crack in a piston? Leak down testers can spot this right away.

Sensors and electrical do not usually mess up after 5 minutes, it's possible but rare.
Try pulling the choke knob when it bogs and see if that makes any difference.

When fixing these bikes for years it becomes seat of the pants type thing, hearing, touching and seeing the motorcycle makes all the difference, sometimes just a sound it makes steers me in the right direction.
In your case I would be curious what vanishes, my fuel, my compression, or my spark?
After it stalls does it seem like it's easier to kick over? Less compression?



flabdog
Posts
13
Joined
3/12/2017
Location
GB
4/2/2017 3:11am
It is very hard to figure out these type of problems over a computer, true diagnostics require a step by step process. 3 parts replaced or...
It is very hard to figure out these type of problems over a computer, true diagnostics require a step by step process.

3 parts replaced or fixed. New or rewound stator, coil and air pressure sensor. None of these actually fixed the symptom of it bogging or cutting out.

It does run good for 5 minutes.
I am not sure what is wrong. I wouldn't worry about the fuel pump or fuel pressure if it runs good for 5 minutes.
Do not let anyone sell you an electrical part unless they promise a full refund if it does not fix it!
While it was bogging I would loosen the fuel cap and see if the cap wasn't venting causing vapor lock.
If it still died with the cap off I would rule out vapor lock and cool the engine with a big fan, see if it starts when it's ice cold. If it starts up cold I might think I have some weird heat related problem killing it when hot, like a small crack in a piston? Leak down testers can spot this right away.

Sensors and electrical do not usually mess up after 5 minutes, it's possible but rare.
Try pulling the choke knob when it bogs and see if that makes any difference.

When fixing these bikes for years it becomes seat of the pants type thing, hearing, touching and seeing the motorcycle makes all the difference, sometimes just a sound it makes steers me in the right direction.
In your case I would be curious what vanishes, my fuel, my compression, or my spark?
After it stalls does it seem like it's easier to kick over? Less compression?



Thanks for the reply, great post.
Ill try the fuel cap and choke today to see if it makes any difference.
After the bike stalls its roughly the same compression wish when it kicks over.
flabdog
Posts
13
Joined
3/12/2017
Location
GB
4/3/2017 8:47am
It is very hard to figure out these type of problems over a computer, true diagnostics require a step by step process. 3 parts replaced or...
It is very hard to figure out these type of problems over a computer, true diagnostics require a step by step process.

3 parts replaced or fixed. New or rewound stator, coil and air pressure sensor. None of these actually fixed the symptom of it bogging or cutting out.

It does run good for 5 minutes.
I am not sure what is wrong. I wouldn't worry about the fuel pump or fuel pressure if it runs good for 5 minutes.
Do not let anyone sell you an electrical part unless they promise a full refund if it does not fix it!
While it was bogging I would loosen the fuel cap and see if the cap wasn't venting causing vapor lock.
If it still died with the cap off I would rule out vapor lock and cool the engine with a big fan, see if it starts when it's ice cold. If it starts up cold I might think I have some weird heat related problem killing it when hot, like a small crack in a piston? Leak down testers can spot this right away.

Sensors and electrical do not usually mess up after 5 minutes, it's possible but rare.
Try pulling the choke knob when it bogs and see if that makes any difference.

When fixing these bikes for years it becomes seat of the pants type thing, hearing, touching and seeing the motorcycle makes all the difference, sometimes just a sound it makes steers me in the right direction.
In your case I would be curious what vanishes, my fuel, my compression, or my spark?
After it stalls does it seem like it's easier to kick over? Less compression?



Had a compression test done today. Service manuel say it should be between 62-103 psi. We 90 psi would that suggest the piston is fine ?

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