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2018 KX250F shutting down

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Hello guys,

I'm a beginner rider, I don't rip my bike hard.

My bike fires with 2 kicks when cold. It can idle for 2 minutes and it will shut down by itself and then It won't let me kick start without choke. After riding for a couple min' it wants to shut down when reaching low rpm and won't respond to opening throttle and have a delay, then it will respond and give power. But something is definitely weird.

I gave a friend a small test lap and he only felt it once.

When the bike is hot, it will start with 1 small kick, when I put into 1st while clutch is pulled all the way in, I rev it a little and it shuts down without releasing the clutch. I can ride it if I throw the clutch a bit and rev higher, but I never had this issue before.

also while riding, it randomly wants to shut down, like it's choking or not getting fuel (usually happens in low rpm). If I rev it, it goes back to normal. I've had this happen even in 5th gear going downhill without throttle, getting to the end of the downhill with low rpm the bike losing power and won't respond to throttle opening and shutting down. I can kick it and continue to ride but it will happen again randomly.

The first time I noticed something is wrong was when I went wide open in 5th gear and felt for a split second like there was a cut in fuel / air and then it kept going as normal. But since that day, it's been worse each time. Not sure what's the problem.

It's a brand new 2018 KX250F from the dealer. I've done +30 hour. Never done valve clearance yet. Will do next week, but don't know if it's related, because the bike starts with first kick, but acting weird when riding.

Edited by Titan777

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It is always good to check all the electrical couplers for water or dirt and use only suitable contact spray (never use WD40 or similar).

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4 hours ago, phatsmall said:

It is always good to check all the electrical couplers for water or dirt and use only suitable contact spray (never use WD40 or similar).

if I rode in the rain (was very light rain), can this cause this issue? Last time it didn't do anything when it was raining.

Today I tried to start the bike and everything went normal, even rode a bit in the dealer parking lot. We thought nothing is wrong, since I changed the air filter and cleaned the plug.
But when I came back later to pick up the bike (they can't fix the bike until Wednesday), suddenly after starting and trying to ride, 1st gear shuts the bike off when revving just a little bit without clutch release. Even the mechanic tried to ride and the bike would shut down once he revs and tries to release the clutch in gear. Said something it wrong (obviously).
It's like in low rpm the bike wants to die but if I pass that with aggressive throttle, it's kind of back to normal. But I did notice lack of power, in 5th gear the bike felt weak and sounded too screamy in about 60% throttle. Felt like it's 3rd gear, didn't pull hard and the speed wasn't high for normal 5th gear.
 

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If with the electrical couplers everything is normal you should not face any problems in hard rain or washing the bike with water pressure.

But if you have such a problem with a bad sealed coupler you will face such an issue doesn't matter you ride in rain or not.

I believe the mechanic at the official dealer's shop knows better.

It is also strange you don't have flash showing a code.....

Have they tried to connect it to diagnostic tool?

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1 hour ago, phatsmall said:

If with the electrical couplers everything is normal you should not face any problems in hard rain or washing the bike with water pressure.

But if you have such a problem with a bad sealed coupler you will face such an issue doesn't matter you ride in rain or not.

I believe the mechanic at the official dealer's shop knows better.

It is also strange you don't have flash showing a code.....

Have they tried to connect it to diagnostic tool?

Didn't connect to the Kawi computer yet, they will have the new updated Kawi software on Wednesday so I'm waiting. What do you mean flash code? Where does it show? (the red blink light on the launch control?)

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6 hours ago, Titan777 said:

 What do you mean flash code? Where does it show? (the red blink light on the launch control?)

Look at pages 179-193 of your owners manual.

Edited by dslpow3r

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On 12/4/2018 at 12:42 AM, dslpow3r said:

Look at pages 179-193 of your owners manual.

Can it show the codes if I get my bike running, and don't need to connect to a 12 v battery?

Just kick it in neutral and wait for the light to blink?

Edit: I tried. lol... Nothing happend. Guess I need to connect to the Kawi diag software, etc..

I replaced a new plug an hour ago and tried to see if something has changed but still the same issue, the bike fires in 2 kicks but the power delivery is weird, has a delay and burst of power, like it's choking and releasing... as if you would stop a water hose for a moment and let go. Feels choked and snappy.... Also I felt like it wants to shut off but if I put more throttle it doesn't shutdown. (was just riding in the parking lot 1st \ 2nd gear).

Another weird thing, when going downhill in 2nd, I pulled the clutch all in to see if the bike will shut off and it did. When I released the clutch it started (still going downhill).

Edited by Titan777

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3 hours ago, skorpan777 said:

Probably some shortcut somewhere, check all cables

The bike had a diagnostic test at the Kawi dealer and all is fine according to that. Fuel pump pressure was 50 psi.

We didn't check the TPS output yet.

The dealer owner just tried to ride it and I told him to pull in the clutch while riding for example in 2nd gear and the bike would shut off. Pulled the clutch while riding in 1st gear and it will shut off, let go the clutch and it will start again.

When riding very slow in 1st gear the bike doesn't stall. Only if clutch is pulled it will want to shut off.

Also would like to add that when I put into 1st gear and try to find the clutch engagement point, the bike doesn't shut off. It can glide very slowly in that point, like it should.
But once I add throttle it will shut down.
If I do this process more aggressively, throwing a bit clutch and more throttle, it won't shut off.
Bike fires with 1 kick.

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With a short cut I mean like damage /loose cable that you can miss with a diagnostic because its accors only sometimes and more if it's more vibration like when coming up in speed. 

it's just a guess?

It's a pain with this cinda of problems 

Cheers 

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On 12/13/2018 at 8:37 PM, skorpan777 said:

With a short cut I mean like damage /loose cable that you can miss with a diagnostic because its accors only sometimes and more if it's more vibration like when coming up in speed. 

it's just a guess?

It's a pain with this cinda of problems 

Cheers 

The problem was the air temp sensor. Not sure exactly what, maybe didn't sit properly in the mount, maybe a bad wire.

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On 2/4/2019 at 12:34 AM, Titan777 said:

The problem was the air temp sensor. Not sure exactly what, maybe didn't sit properly in the mount, maybe a bad wire.

I quite sure it is bad wire or coupler (bad electrical contact), but the most important is you have fixed the problem.

So just go ride and have fun 🙂

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