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CRF250X engine get super hot super fast and then struggles to start hot and dies hot very easily

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Hi everyone. I’m new here so I don’t really know what to do but let me explain what’s up, so I bought this 2008 CRF250X today and everything looked in tip top shape, but within a few minutes of riding the engine and radiator gets to hot to touch and then the bike dies at low RPM, then it is a hassle to get it started(i drained the battery trying) and once it fires it dies super easily again like by touching the trottle or just idling and I have to be super cautious on the throttle to grt it going. I don’t know if it is overheating or if there is another problem, if anyone could help me it would be very much appreciated.

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<<gets to hot to touch>>

That's normal

<<and then the bike dies at low RPM>>

Probably getting lean.

<<then it is a hassle to get it started(i drained the battery trying) >>

  Are you using the hot start lever?

<< and once it fires it dies super easily again like by touching the trottle or just idling and I have to be super cautious on the throttle to grt it going.>>

  Does it die when you slowly roll it on, or is it with a quick snap?   There are different things in the carb that contribute to each.

  First, with it cooled down, I would check that the coolant level is where it should be.

  Second is you'll want to adjust the fuel screw (which basically checks that the slow jet is correct).

  Third would be to check the main jet, needle, and clip position assuming your still have problems.

  Also post back with:

  Altitude and temps you ride at.

  How the has been modified (is the air box open, backfire screen removed, has after market exhaust, etc).

Jim.

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37 minutes ago, Jim Dettman said:

<<gets to hot to touch>>

That's normal

<<and then the bike dies at low RPM>>

Probably getting lean.

<<then it is a hassle to get it started(i drained the battery trying) >>

  Are you using the hot start lever?

<< and once it fires it dies super easily again like by touching the trottle or just idling and I have to be super cautious on the throttle to grt it going.>>

  Does it die when you slowly roll it on, or is it with a quick snap?   There are different things in the carb that contribute to each.

  First, with it cooled down, I would check that the coolant level is where it should be.

  Second is you'll want to adjust the fuel screw (which basically checks that the slow jet is correct).

  Third would be to check the main jet, needle, and clip position assuming your still have problems.

  Also post back with:

  Altitude and temps you ride at.

  How the has been modified (is the air box open, backfire screen removed, has after market exhaust, etc).

Jim.

Thanks Jim, my altitude is 1350 meters or 4429 feet above sea level which is 300m or 980 foot lower than the previous owner and at the moment the temperature would average around 25 but in summer should be around 33. I use the hot start lever but it doesn’t seem to be making a difference amd if it does it is only the slightest difference, it dies when i roll it slowly when it’s very hot or when I’ve started it for the first time when it’s cold and it always dies with a snap. With it cooled down the coolant sits at upper which I am assuming is abit to much? I will check all the jets but i am not sure on how to adjust the fuel screw. Everything on the bike is stock except for a new air filter and the spark arrestor or the backfire screen has been removed.

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<<With it cooled down the coolant sits at upper which I am assuming is abit to much? >>

 No, should be full up to just about the neck.

<< but i am not sure on how to adjust the fuel screw.>>

 On a warmed up motor:

1. Lower the idle until just running.

2. Adjust the fuel screw for the smoothest running.

3. Repeat # 1 and 2 until you can't keep it running.   You may want to put a fan on the radiator while you do this.

4. Raise the rpms to 1,700.

 After that, if your <1 turn on the fuel screw, you need a smaller slow jet.   If more than 2 1/4 - 2 1/2 turns out, you need a larger one.    But with that said, a #42 is pretty much it.   So if you pull it out and it is a #42, I would replace it first and then do the fuel screw adjustment again.   They are easily plugged and difficult to clean well.

When your done with that, you should be able to:

1. Pull the hot start *slightly* and get a rise in rpms.

2. Pulling it in all the way should kill the motor.

3. Pulling the choke out on it's own should kill the motor.

 If you can do the above, it means your slightly rich on the idle circuit, which is where you want to be.   Always better to be rich than lean.   Even being slightly lean gives you a lot of odd problems and the motor runs hot.   But if your rich, you need to be very rich before you will have problems, so you always want to be on the rich side.

 If you getting popping on decel after this, you can turn the fuel screw a 1/4 turn out to take care of it.

Also:

1. Check the band clamps on the carb boot....make sure they are tight.   

2. Check for any signs of cracking or flaring at the ends of the boot.   If your letting air in, your leaning out.  If you think you have a crack, you can check with a handheld propane torch.  Crack the valve *slightly*, leave it un-lit, and with the bike running, go all around the carb boot.   If there is a crack and it is sucking in air, the propane will get sucked in and the rpms will increase.

3. Not sure if you have an after market fuel screw or not, but make sure the spring, washer, and o-ring are in the correct order (o-ring goes in first) and that there is only one o-ring on it (and none stuck up in the carb either).

4. Look over the hot start nut carefully and make sure it is not cracked.

5. Check the hot start plunger....it should move freely.

 If you can't get it to idle well after all that, then the carb needs a good cleaning.

 Once you have the idle squared away, move onto the main jet, needle, and clip position (assuming you have to).

 The bikes come jetted very lean from the factory and it's possible that it's never been adjusted.

Jim.

 

 

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20 minutes ago, Jim Dettman said:

<<With it cooled down the coolant sits at upper which I am assuming is abit to much? >>

 No, should be full up to just about the neck.

<< but i am not sure on how to adjust the fuel screw.>>

 On a warmed up motor:

1. Lower the idle until just running.

2. Adjust the fuel screw for the smoothest running.

3. Repeat # 1 and 2 until you can't keep it running.   You may want to put a fan on the radiator while you do this.

4. Raise the rpms to 1,700.

 After that, if your <1 turn on the fuel screw, you need a smaller slow jet.   If more than 2 1/4 - 2 1/2 turns out, you need a larger one.    But with that said, a #42 is pretty much it.   So if you pull it out and it is a #42, I would replace it first and then do the fuel screw adjustment again.   They are easily plugged and difficult to clean well.

When your done with that, you should be able to:

1. Pull the hot start *slightly* and get a rise in rpms.

2. Pulling it in all the way should kill the motor.

3. Pulling the choke out on it's own should kill the motor.

 If you can do the above, it means your slightly rich on the idle circuit, which is where you want to be.   Always better to be rich than lean.   Even being slightly lean gives you a lot of odd problems and the motor runs hot.   But if your rich, you need to be very rich before you will have problems, so you always want to be on the rich side.

 If you getting popping on decel after this, you can turn the fuel screw a 1/4 turn out to take care of it.

Also:

1. Check the band clamps on the carb boot....make sure they are tight.   

2. Check for any signs of cracking or flaring at the ends of the boot.   If your letting air in, your leaning out.  If you think you have a crack, you can check with a handheld propane torch.  Crack the valve *slightly*, leave it un-lit, and with the bike running, go all around the carb boot.   If there is a crack and it is sucking in air, the propane will get sucked in and the rpms will increase.

3. Not sure if you have an after market fuel screw or not, but make sure the spring, washer, and o-ring are in the correct order (o-ring goes in first) and that there is only one o-ring on it (and none stuck up in the carb either).

4. Look over the hot start nut carefully and make sure it is not cracked.

5. Check the hot start plunger....it should move freely.

 If you can't get it to idle well after all that, then the carb needs a good cleaning.

 Once you have the idle squared away, move onto the main jet, needle, and clip position (assuming you have to).

 The bikes come jetted very lean from the factory and it's possible that it's never been adjusted.

Jim.

 

 

Thanks so much, I will do exactly that tomorrow morning and when I will come back to you as soon as possible.

 

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>
 No, should be full up to just about the neck.
>
 On a warmed up motor:
1. Lower the idle until just running.
2. Adjust the fuel screw for the smoothest running.
3. Repeat # 1 and 2 until you can't keep it running.   You may want to put a fan on the radiator while you do this.
4. Raise the rpms to 1,700.
 After that, if your When your done with that, you should be able to:
1. Pull the hot start *slightly* and get a rise in rpms.
2. Pulling it in all the way should kill the motor.
3. Pulling the choke out on it's own should kill the motor.
 If you can do the above, it means your slightly rich on the idle circuit, which is where you want to be.   Always better to be rich than lean.   Even being slightly lean gives you a lot of odd problems and the motor runs hot.   But if your rich, you need to be very rich before you will have problems, so you always want to be on the rich side.
 If you getting popping on decel after this, you can turn the fuel screw a 1/4 turn out to take care of it.
Also:
1. Check the band clamps on the carb boot....make sure they are tight.   
2. Check for any signs of cracking or flaring at the ends of the boot.   If your letting air in, your leaning out.  If you think you have a crack, you can check with a handheld propane torch.  Crack the valve *slightly*, leave it un-lit, and with the bike running, go all around the carb boot.   If there is a crack and it is sucking in air, the propane will get sucked in and the rpms will increase.
3. Not sure if you have an after market fuel screw or not, but make sure the spring, washer, and o-ring are in the correct order (o-ring goes in first) and that there is only one o-ring on it (and none stuck up in the carb either).
4. Look over the hot start nut carefully and make sure it is not cracked.
5. Check the hot start plunger....it should move freely.
 If you can't get it to idle well after all that, then the carb needs a good cleaning.
 Once you have the idle squared away, move onto the main jet, needle, and clip position (assuming you have to).
 The bikes come jetted very lean from the factory and it's possible that it's never been adjusted.
Jim.
 
 

IMG_6494.JPG
I’m pretty sure there is no fuel screw unless it is located somewhere else

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 You have the stock fuel screw.   Right below and slightly to the left of the slotted idle speed adjustment are two screws.

 Directly below that is a hole; the fuel screw is in that.   It will have a "D" shaped head more than likely.  

 You'll want to replace it with an aftermarket one.   Most use the RD Flex screw:

https://www.rockymountainatvmc.com/p/1151/22925/R-%26-D-Racing-Flex-Jet-(Remote-Fuel-Screw)

 There are also cheaper alternatives out there.   Most have a large knob that sticks out so you can adjust it easily.

 If it does have the "D" head on it, a blue electrical butt connector will fit over it and you'll be able to remove it.

 You can also now buy the bit for it for about $4 - $6:

https://www.amazon.com/Motion-Pro-D-Shape-Replacement-08-0229/dp/B003CMWC4U

look what it has first though with a mirror or loosen the carb and twist it around.

Jim.

 

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<<With it cooled down the coolant sits at upper which I am assuming is abit to much? >>

 No, should be full up to just about the neck.

 

Are you checking the actual radiator or the overflow tank? Don't fill the overflow tank up to the neck.

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 No, should be full up to just about the neck.
 
Are you checking the actual radiator or the overflow tank? Don't fill the overflow tank up to the neck.


The radiator is full to the neck and the overflow tanks is at halfway

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