Reply To: GT250 EFI 2013 Sluggish Starts.
I have had a few engines apart a few times, sometimes the pistons will be in different positions. I open the top valve covers to do clearance jobs , so i can either spin by hand to confirm the timings are correct , then i use a starter motor to battery to see if it will crank OK but ofcourse oil will shoot out!
Once the engine is completed and closed up, it did not matter where the piston was, the bike cranks within 2 seconds after the fuel pump stops priming. At some time ago, it took longer than 5 seconds to spin and start but it sounded weary.
So I removed the flywheel, and some some teeth of the sprag-clutch was gone , could this be related ?
Have you ever taken off your flywheel to inspect your starter-clutch system for abnormal wear / damage?
I recently worked on a customer’s 2017 bike GV250, it was a delphi. It was a stressful job! I changed a lot of things despite positive readings on the meter, the harness was clean as it could be , no wire oxidization yet (garage queen) , but i was shocked that in the end I replaced the stator unit & made sure the battery is 100% charged and brand new , voila it started within 2 seconds of the fuel pump priming. I didn’t really investigate too much as if “piston” position had any influence to how the ECU expects the piston to be.
However, everytime i press start (within a milli second) ==>i see sparks on the spark plug which tells me , the ECU had already been ready to fire up the coils as soon as i hold the clutch switch in. The suspicion in my mind right now is that it did not matter if the front was up, and rear was down or rear up and front down position of pistons , it always started in 2 seconds. Longer cranks in my past were a result of the fuel injection system needing a clean or fuel pump was underperforming. I did not keep DELPHi systems for long , but i always had Daewoo & Sentecs bikes to work on. Sometimes my customers ask me to just convert the machines to “carby” (expensive investment but less maintenance in the long run however the DELPHi system is not too bad, and is more “instant response” with throttle which is good)
As i get more information , I will share when i can. I don’t think i’ve heard too many people discuss piston position vs cranking time for ECU. I have to keep in mind both cylinders are connected to the same crank anyway! Everytime the bike is switched off (during a crash, or normal riding to stop or rider activates killswitch, the pistons don’t always return to the same position as they did before , a bike could be switched off mid cycle. )