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I am working on my motorcycle Honda cbr 250r recently i wanted to clean the throttle body because it would hesitate to start. so i have cleaned the valve and the IAC motor, then the problem become much worse it would take long time cranking to get it started after which i could not apply throttle it would buck and shut off. once the bike has warmed up it would drive good. all this lead to Faulty IAC valve or operation of it.
researching about it i found a reset procedure, I have carried out the process to the T but still the same issue suspected a fuel pressure problem i have removed the tank to see the pump and pressure regulation valve no issue that i could see i suspect the fuel filter (remember i don't have pressure gauge (in india they dont have it in stores )) now when i tried to take it for ride it has slight stumble upon acceleration.
any pointers would help and i would keep you all posted on upcoming progress
I would suggest checking the valve clearance. Most motorcycles require yearly periodic valve adjustments/ checks on their service schedule. It is possible to pull the intake boot and exhaust off and look at the valve stem. If the valve seat has sealing issues, the stem of the valve will be more black than the others. Will be an easy sign of which valve is the issue. Usually this issue is associated with hot “no/ hard start issues”.
so with fuel issue in mind i cleaned the injector and hose from fuel pump to injector. Replaced the fuel filter with an old filter to test and process of elimination. put back the entire assembly still the same issue. previously i worked on a cruiser bike where it had a stale gas(petrol) in it i had to replace fuel pump and pressure regulation valve to make it work. so i drained some fuel and then i went to reputed fuel bunk to fill fresh fuel. the issue is magically disappeared.
all along the issue is stale or poor quality fuel affected my diagnostic. remember this issue never manifested as fuel related, delayed or long crank time might put you on different path, the throttle performance or slight hesitation during acceleration manifested later as it tend to degrade more over time. with hesitation as clue i narrow down the fuel or fuel delivery as a culprit. also taken into account that the fuel never smelt bad.
hope this gives the happy ending and a lesson on diagnostic
i wrote this just to keep this as a tip while diagnosing
no i dont want to touch on valves even for that matter the spark system because the once the vehicle is started it drives like no issue. this logic in mind i never suspected the valve or spark timing
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