12 kx250f hard to start

Dhibbz927
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Dhibbz927
Fully rebuilt motor crank head piston 14.1 with full mod head iv replaced harnes tps Ecu throttlebody plug no codes come up for the diagnostic check extremely hard to start on a kick when it starts it runs great timing is deff on valves are in spec running Sunoco 110 it’s bien to 2 other top mechanics in the area I’m lost any ideas
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Paul_Pitzonka
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Paul_Pitzonka 1/31/2020 8:35pm
1/31/2020 8:35pm Edited Date/Time 1/31/2020 8:40pm
Map sensor, coolant temp sensor, incorrectly calibrated TPS, weak fuel pump/ dirty injector (doubtful) are all possibilities ... Are you running a stock map? I’ve come across incorrectly mapped bikes that are almost impossible to start... what has been changed on the engine? Full mod head doesn’t tell much (oversized valves, porting, change in cams?)
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kb228
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kb228 2/1/2020 6:48am
2/1/2020 6:48am
Make sure the map and tps voltage is correct since you replaced them.
Dhibbz927
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Dhibbz927 2/2/2020 8:22pm
2/2/2020 8:22pm
Yes stock map I tested fuel pump and cleaned injectors The head is a pro malsko mph head port polish shaved berilium seats oversized titanium valves all new guides retainers springs ext stock cams 14:1 cp piston oem crank bearings seals new timing chain Is there a way to test the neutral safety switch I played around with tps , idle , with no luck. I have started off a kick but it takes like a 100 kicks from tdc could it need to be remapped because of the build ?
RGaede
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RGaede 2/2/2020 10:19pm
2/2/2020 10:19pm
See if you can find someone to swap a tank with to try a different fuel pump. I've had the exact same symptoms, and it was the pump taking forever to build pressure back up after the bike was sitting for a while. I dont remember how that pump tested, did you check pressure and volume?

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Paul_Pitzonka
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Paul_Pitzonka 2/3/2020 9:06am
2/3/2020 9:06am Edited Date/Time 2/3/2020 9:16am
Dhibbz927 wrote:
Yes stock map I tested fuel pump and cleaned injectors The head is a pro malsko mph head port polish shaved berilium seats oversized titanium valves...
Yes stock map I tested fuel pump and cleaned injectors The head is a pro malsko mph head port polish shaved berilium seats oversized titanium valves all new guides retainers springs ext stock cams 14:1 cp piston oem crank bearings seals new timing chain Is there a way to test the neutral safety switch I played around with tps , idle , with no luck. I have started off a kick but it takes like a 100 kicks from tdc could it need to be remapped because of the build ?
You’ve effectively changed the compression ratio and the amount of Air your engine flows you would most definitely benefit from having it properly mapped...

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