2011 kx250f start and idle issue

Went to the track today and started the bike up without choke. Didn't wait for it to warm up. I cruise slowly about 50 m to get out on the track but the bike seamed to get to much fuel so I stopped. I couldn't keep the bike running. Tried to start it again but no luck. Bump started it but it didn't run clean. Tried to kick start it and the only way to get it started was to twist the throttle, couldn't get the bike to run clean and snappy. Where do I start searching? TPS, connections, spark plug, valves...... Last time I rode it it was running fine, the only thing I did was to refuel, change airfilter, wasch it and made adjustments to the throttle cabels. The bike has 20 hours on it.

probably your tps seems to be a big issue with that right now..

Mine did the SAME exact thing. TPS sensor is broken. 150 bucks from the stealership, or 135 on thumpertalk. I'm going to be building a bracket to cover this so its not an ongoing issue costing me DNS's and DNF's in motos if/when my boot hits it or I get tangled with somebody.

Thanks guys for your input, I suspected the TPS. Is there a way to test it? You cant see any damage and the bike ran great last time. On a carbed bike I remember that you could measure the resistans in the TPS, is it possible to disconnect It and try to start the bike to see how it reacts.

Edited by TBC

can i ask why you started the bike without the choke? i have noticed mine starts alot easier without the choke (like 3 kicks as opposed to god knows how many) when its cold and have no idea why. thanks

I've noticed that it's easier to start whitout choke when the temperatur is above 20 degrees C. Yesterday the temperatur was 27 degrees C.

Edited by TBC

Okay, so I've checked the valve clearance, the spark plug and every connection and everything is in order. Unplugged the TPS and the engine started on the second kick and ran clean. Connected the TPS and the engine stopped.

My best guess is that the TPS is the problem as you guys thought. Measured the resistance between pin 1 and 3 to 1,1 k ohm on idle and then twisted the throttle with no difference in resistance. Tested the same thing on my other 2011 kx250f and the resistance was 1.4 k ohm on idle and with full throttle 4 k ohm.

Went to the dealer and ordered a new TPS (210$). The dealer thought that Kawasaki will replace it for free.

The problem will be to adjust the new TPS without a service manual. Asked the dealer how much the manual was (200$) and decided not to buy one.

As I remember from erlier non EFI bikes I've had there is a formula in the service manual so you can measure the voltage and then calculate the proper resistance. I know that if you rotate the TPS counter clockwise or you increase the idle speed the resistance increases. Is ther anyone with a service manual that can post a scan on the TPS page or the formula the right numbers an the colour of the cords it would be greatly appriciated.

If anyone knows a website that sells a downloadable pdf service manual that would be appriciated to.

V=I * R. Physics stuff from college. Voltage = current * resistance. To solve for R its, Resistance = Voltage/ Current. I bought a manual for my 05 kx 250 two stroke online for like 3 dollars, i just did a Yahoo search for it. hope this helps.

Got the TPS and installed it, works like a charm. Got the TPS and the right values to adjust it to from my dealer for free. Idle output voltage 0,58-0,62 V and input voltage 5 V.

Edited by TBC

Good to hear all is fixed. I purchased my service manual at Rocky Mountain ATV for about 80$.


I SAW THAT TOO! somebody had an ad on their that said they are on national backorder and we have the only ones, 400$. Are these things really on national backorder? Spoke with Matts honda/kawi in coxsakie new york and they said they were on back order, but they would pull one of a bike in a crate for me if need be. Local dealer to me in albany (phibbs powersports) had one for me in 3 days? How could they get one If i ordered on friday and have it tuesday if they are truely on back order?

EDIT: Glad I didnt buy my bike from them, and was considering it too. If anybody wants the info of the dealer I used to get mine, PM me! They are normal price, not almost 3 times as much like chaplin is trying to do.

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