2011 kx 250f need help

nadeauracing229
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nadeauracing229
Edited Date/Time 6/13/2012 9:35pm
So long story short we just put the bike back together after the 2nd blowup and now it will not run right it runs fine on the stand idleing but when you try to ride or give the bike gas it spits and sputters badly what could the problem be?
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Bob454
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Bob454 6/13/2012 9:27am
6/13/2012 9:27am
Sounds like a timing issue, and you should probably sell your tools
pete24
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pete24 6/13/2012 9:27am
6/13/2012 9:27am
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
nadeauracing229
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nadeauracing229 6/13/2012 9:29am
6/13/2012 9:29am
Bob454 wrote:
Sounds like a timing issue, and you should probably sell your tools
Well we thought it could be this and we actually took it apart and checked it and then had someone else do it and it looks spot on but maybe we are wrong could this cause the issue? It still starts and runs fine low rpm's.
nadeauracing229
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nadeauracing229 6/13/2012 9:31am
6/13/2012 9:31am
pete24 wrote:
check for reeds cracked powervalve opening all the way carb clean? put in a fresh br9egv o sorry i was talking about a bike u could...
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
Angry Hahaha! We have a 2 stroker also that just randomly lost spark last time riding and we are trying to findout what that could be, we have had quite the bad luck lately.

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Bob454
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Bob454 6/13/2012 9:36am
6/13/2012 9:36am Edited Date/Time 6/13/2012 9:37am
pete24 wrote:
check for reeds cracked powervalve opening all the way carb clean? put in a fresh br9egv o sorry i was talking about a bike u could...
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind.

Can be a large list of things but start with the simple...is the plug and fuel fresh? My guess would be dirty fuel injector, could also be weak fuel pump

Could be a weak coil, sheered key way on flywheel (unlikely), weak stator,

Can you post a video? It is alot easier to diagnose if it can be seen/heard what it is doing.
RNagy052
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RNagy052 6/13/2012 9:41am
6/13/2012 9:41am Edited Date/Time 6/13/2012 9:42am
Bob454 wrote:
Sounds like a timing issue, and you should probably sell your tools
nadeauracing229 wrote:
Well we thought it could be this and we actually took it apart and checked it and then had someone else do it and it looks...
Well we thought it could be this and we actually took it apart and checked it and then had someone else do it and it looks spot on but maybe we are wrong could this cause the issue? It still starts and runs fine low rpm's.
Yes, you can have a 4 stroke start with the timing off one tooth, and it will act like that. Double check your timing marks again.

Another thing that sometimes makes it look spot on but it is not, is if you check it with the chan tensioner off, and it looks fine, then you engage the chain tensioner and it pulls the gears back towards the intake from the tenion on the chain, then it doesn't look lined up right, if you check it then. Just that little bit could have it off by one tooth. With dual cams, you may still have the right amount of pins between the intake and exhaust cams, so they look lined up, but in fact they are both off by one tooth.

If you have a manual, take a look in there for a picture showing the tick marks the way they should be lined up.
pete24
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pete24 6/13/2012 9:48am
6/13/2012 9:48am
pete24 wrote:
check for reeds cracked powervalve opening all the way carb clean? put in a fresh br9egv o sorry i was talking about a bike u could...
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
Bob454 wrote:
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind. Can be a large list of things but start with the...
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind.

Can be a large list of things but start with the simple...is the plug and fuel fresh? My guess would be dirty fuel injector, could also be weak fuel pump

Could be a weak coil, sheered key way on flywheel (unlikely), weak stator,

Can you post a video? It is alot easier to diagnose if it can be seen/heard what it is doing.
your kidding me rite? 4 strokes are wicked haaaad to work on i would NEVER attempt it!
nadeauracing229
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nadeauracing229 6/13/2012 9:53am
6/13/2012 9:53am
pete24 wrote:
check for reeds cracked powervalve opening all the way carb clean? put in a fresh br9egv o sorry i was talking about a bike u could...
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
Bob454 wrote:
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind. Can be a large list of things but start with the...
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind.

Can be a large list of things but start with the simple...is the plug and fuel fresh? My guess would be dirty fuel injector, could also be weak fuel pump

Could be a weak coil, sheered key way on flywheel (unlikely), weak stator,

Can you post a video? It is alot easier to diagnose if it can be seen/heard what it is doing.
Ok I will have a video up in about 10 minutes but the plug is fresh the bike has sat about a month while we had to buy parts for it so that could contribute.
twosmoke30 6/13/2012 9:56am
6/13/2012 9:56am
id check timing first, as that's usually the culprite
crashnburn11 6/13/2012 9:58am
6/13/2012 9:58am
Bob454 wrote:
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind. Can be a large list of things but start with the...
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind.

Can be a large list of things but start with the simple...is the plug and fuel fresh? My guess would be dirty fuel injector, could also be weak fuel pump

Could be a weak coil, sheered key way on flywheel (unlikely), weak stator,

Can you post a video? It is alot easier to diagnose if it can be seen/heard what it is doing.
I'm with this guy. Yes, my 250f is more complicated to change the top end than the two stroke, but it is not harder to work on. It is just a couple of extra steps. If you are halfway intuitive you won't have any problems on a 4 stroke either.
ML512
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ML512 6/13/2012 9:59am
6/13/2012 9:59am
pete24 wrote:
check for reeds cracked powervalve opening all the way carb clean? put in a fresh br9egv o sorry i was talking about a bike u could...
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
Bob454 wrote:
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind. Can be a large list of things but start with the...
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind.

Can be a large list of things but start with the simple...is the plug and fuel fresh? My guess would be dirty fuel injector, could also be weak fuel pump

Could be a weak coil, sheered key way on flywheel (unlikely), weak stator,

Can you post a video? It is alot easier to diagnose if it can be seen/heard what it is doing.
nadeauracing229 wrote:
Ok I will have a video up in about 10 minutes but the plug is fresh the bike has sat about a month while we had...
Ok I will have a video up in about 10 minutes but the plug is fresh the bike has sat about a month while we had to buy parts for it so that could contribute.
If it sat for a month id take the injector out and clean it, u take it out and hook a car battery up to the the plugs sticking out and it will open then spray carb cleaner through it and see what comes out. Just a suggestion that is.
ML512
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ML512 6/13/2012 10:02am
6/13/2012 10:02am
pete24 wrote:
check for reeds cracked powervalve opening all the way carb clean? put in a fresh br9egv o sorry i was talking about a bike u could...
check for

reeds cracked
powervalve opening all the way
carb clean?
put in a fresh br9egv







o sorry i was talking about a bike u could work on
Bob454 wrote:
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind. Can be a large list of things but start with the...
Face palm....four strokes are not complicated, stop letting pre mix cloud your already slow mind.

Can be a large list of things but start with the simple...is the plug and fuel fresh? My guess would be dirty fuel injector, could also be weak fuel pump

Could be a weak coil, sheered key way on flywheel (unlikely), weak stator,

Can you post a video? It is alot easier to diagnose if it can be seen/heard what it is doing.
pete24 wrote:
your kidding me rite? 4 strokes are wicked haaaad to work on i would NEVER attempt it!
And thats why the sport has people like you to take your stuff to the dealer and pay for it to be worked on Wink Try fixing Big inline 6's or V12's out of mine sized heavy equipment then come on here and talk about hard to work on!!! Four stroke bikes are not that big of a learning curve... Rant over...
Bob454
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Bob454 6/13/2012 10:21am
6/13/2012 10:21am
pete24 wrote:
your kidding me rite? 4 strokes are wicked haaaad to work on i would NEVER attempt it!
Not kidding you at all, I bet if you would actually take the time and attempt to work on them you would realize it is not that big of a deal.

For the OP, recheck the timing by counting the number of pins between timing marks, I have not done a kawi in a while but I want to say 29 or 30 pins? Can be easily found online. Also make sure you are using the correct tdc mark on the flywheel.

Next clean your injector by the method stated above, when hooked to a battery it will click open like a relay and you can spray carb cleaner and/or moderate bursts of compressed air.

One more thing not to rule out is your tps (throttle position sensor), when they get out of adjustment the bike can idle but not rev up, and will spit and sputter. If the tps fails the Efi goes into a "full rich" mode and will run like a bike that has the choke on I.e. very blubbery and will not idle.
nadeauracing229
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nadeauracing229 6/13/2012 10:36am
6/13/2012 10:36am
pete24 wrote:
your kidding me rite? 4 strokes are wicked haaaad to work on i would NEVER attempt it!
Bob454 wrote:
Not kidding you at all, I bet if you would actually take the time and attempt to work on them you would realize it is not...
Not kidding you at all, I bet if you would actually take the time and attempt to work on them you would realize it is not that big of a deal.

For the OP, recheck the timing by counting the number of pins between timing marks, I have not done a kawi in a while but I want to say 29 or 30 pins? Can be easily found online. Also make sure you are using the correct tdc mark on the flywheel.

Next clean your injector by the method stated above, when hooked to a battery it will click open like a relay and you can spray carb cleaner and/or moderate bursts of compressed air.

One more thing not to rule out is your tps (throttle position sensor), when they get out of adjustment the bike can idle but not rev up, and will spit and sputter. If the tps fails the Efi goes into a "full rich" mode and will run like a bike that has the choke on I.e. very blubbery and will not idle.
It sounds more like the third thing im trying to get the video now.
nadeauracing229
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nadeauracing229 6/13/2012 10:40am
6/13/2012 10:40am
Won't even start now started with the choke on and I turned it off and the bike turned off did it skip timing?
ML512
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ML512 6/13/2012 10:56am
6/13/2012 10:56am
One other thing that can go bad, I've seen on the 450 but not as common on the 250 is the coolant temp sensor on the back of the cylinder can cause a similiar issue if It's going bad.
Bob454
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Bob454 6/13/2012 12:40pm
6/13/2012 12:40pm
nadeauracing229 wrote:
Won't even start now started with the choke on and I turned it off and the bike turned off did it skip timing?
Sounds like your tps, bump start it and see if you can get t running. If it sounds incredibly rich and blubbery your tps shit the bed.
race250r
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race250r 6/13/2012 5:24pm
6/13/2012 5:24pm
nadeauracing229 wrote:
Won't even start now started with the choke on and I turned it off and the bike turned off did it skip timing?
Bob454 wrote:
Sounds like your tps, bump start it and see if you can get t running. If it sounds incredibly rich and blubbery your tps shit the...
Sounds like your tps, bump start it and see if you can get t running. If it sounds incredibly rich and blubbery your tps shit the bed.
The '11 KX's have a problem with their TPS, it is vulnerably positioned and ill-guarded from mechanical damage or contamination from the elements. I believe you can spec it with an ohmmeter, I would to avoid paying for a part that you wasn't broken.

Check out the KX250F Thumpertalk page, as this topic has been discussed heavily.

Good luck

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nadeauracing229
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nadeauracing229 6/13/2012 7:42pm
6/13/2012 7:42pm
nadeauracing229 wrote:
Won't even start now started with the choke on and I turned it off and the bike turned off did it skip timing?
Bob454 wrote:
Sounds like your tps, bump start it and see if you can get t running. If it sounds incredibly rich and blubbery your tps shit the...
Sounds like your tps, bump start it and see if you can get t running. If it sounds incredibly rich and blubbery your tps shit the bed.
race250r wrote:
The '11 KX's have a problem with their TPS, it is vulnerably positioned and ill-guarded from mechanical damage or contamination from the elements. I believe you...
The '11 KX's have a problem with their TPS, it is vulnerably positioned and ill-guarded from mechanical damage or contamination from the elements. I believe you can spec it with an ohmmeter, I would to avoid paying for a part that you wasn't broken.

Check out the KX250F Thumpertalk page, as this topic has been discussed heavily.

Good luck
Last time the bike ran it had no tps problems.
potatoflake
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potatoflake 3/18/2017 10:44am
3/18/2017 10:44am
I've got a similar issue here just put a new top end my 2012 because it was time no blow up or anything, I did everything to spec and now when I try to snap the throttle wide open from a slow pace it just sputters and chokes like it could be the fuel pump, I just find it really odd that now that I put a fresh top end in it starts acting upright after break in period is over.. Any insight?

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