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runs rough when hot

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We have a 2010 CRF250R with one race season on it. it has a 270 top end and a yoshimira pipe. has always run well untile a recent crash. now it will run well cold but after a couple of laps it starts skipping and sputering like its running out of fuel. also running very lean. pipe gets very hot comeing out of the head down about 10 inches , hotter than normal to the point of turning it purple. fuel pump has been changed, all electricle connections have been cleaned and reconected.

Edited by billcamire
problem listed in wrong place

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There is a lot of talk on here about big bores with an aftermarket kit and how the carb jetting will pull enough fuel to run a big bore. Is it possible that your injected motor will need a re-map for the extra displacement and pipe combo, or do we know if it is automatically compensated by the computer? ANY ONE KNOW?

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The ECM does not compensate for aftermarket add ons. We are trying a re-map now, hopefully that will fix it. the biggest mystery is it was running ok before we crashed and after is when it started to act up. coincidents? we will keep you posted. Thanks

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Update;

replaced fuel injector,checked valve clearance,checked all wiring and connectors,obd not throwing any codes, changed stator, spark plug, remaped, ordered new coil what next? this thing is driving us insane!!!!! oh ya, now its running like crap all the time not just when its hot!!!!!!!

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What side of the bike took the hardest hit? How does it idle, smooth, sporatic and missing?

I'm thinking because it started doing it after it went a couple of laps that it's pulling air in somewhere causing a lean condition which would explain why the pipe is glowing. Now it's doing it all the time is questionable as to what may be wrong.

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Dont know what side the boy crashed on. runs good at idle, has gone back to running good at start up and progressively runs worse as it warms up. coolant sensor mabey?

if the coolant sensor was bad would it act like electricle failure or fuel or both? it almost seems to be electricle

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Yes, the CTS will cause that issue. I would double check the connections. Strange that it wouldn't flash a code if the connection or sensor was bad. The throttle position sensor if not totally jacked up won't set a code iether. Too bad you didn't have access to another 10-12 to swap some parts. It gets expensive with these bikes just guessing.

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thanks for the info Charlie c and yes it is getting very expensive and even more frustrating, fortunatly i can do the work myself. All i`m getting from the dealers is they don`t know that much about the injected bikes yet either. they just want to replace parts untill they fix it at my expense. I can do that an save the labor charge. got the cts on order along with a coil, we`ll keep you posted on the results.

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Before you replace the coil, change the CTS. Don't open the package for the coil so you can return it. I'm not sold that the CTS or the coil is actually bad. It would make it so much easier to have these machines in front of me to trouble shoot this stuff. I hate guessing on most of these issues and I don't like the fact that people just spending money on things that "I think" might be bad. I'm no genius.

Do you have an actual Honda shop manual? A clymer manual is too basic for what you're dealing with. I have a 10 450 manual at home which will work fine for what we're dealing with, but I won't be home until Thursday. At least I can look at the book and get a better what's going on if you can wait a few days?

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sounds good, i will install the CTS first and see how that goes. and yes i do have time so if you would be so kind as to do a little research on this issue i certainly would be gratful for any help i can get. thanks Bill

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I have also recently starting to see the exact same thing on our 2010 250R. It seems to get too little fuel or misfire when it is getting hot, specially on higher gears and under wide throttle openings.

I thought I might be electrical and tried to clean all contacts but it happend again. It seems to behave better if you try to keep it as cool as possible i.e no idling and colder weather. We also tried to change the fuel to a fresh tank of fuel while we were out at the track yesterday. That actually helped for a while.

I'm really interested in learning what you find out. I'm also leaning towards a sensor problem or the coil.

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Well Bill, I looked at the book and the 2 most sensors that I can guess is the MAP or the CTS. You really need to get a Honda book and do some testing before you keep dumping money. I wish I could have this bike. It wouldn't take long to figure it out once you know what the voltage should be at each sensor.

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The CTS is an NTC sensor- resistance goes down as the temp goes up. You should be able to check it with an ohmmeter. Any added resistance would make it run richer. But you could still have a bad sensor telling the ECM it is warmer than it really is. If it is within a range the ECM consider a realistic value, it may not set a fault code. Depending how sophisticated the ECM logic circuitry is, unplugging the CTS may give a fixed value that is richer than the faulty CTS. That may help diagnose the problem. The TPS should also have values that can be checked with a resistance reading.

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CTS installed, ran good for about 15 minutes then right back to running like crap when hot. Next up, map sensor we will keep you posted.

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CTS installed, ran good for about 15 minutes then right back to running like crap when hot. Next up, map sensor we will keep you posted.

Oh - too bad about the CTS. Hope the MAP sensor is the real problem then...

Have you thought about the actual ECU and that it might have gone broken? If you have a similar bike to swap with it might be worth a shot?

Other things might be fuel filters or something with the fuelpump?

Good luck and I really appreciate your updates!

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The ECU has been remapped. that was one of the first things we tried, i am assuming a problem with that would have been detected when we did that. Yes,No Mabey? does anyone have any input?

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Have you taken any resistance readings for any of the components? That can eliminate a lot of guess work.

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