Tim Nelson

The crankshaft position sensor is what the ECU gets the input from to fire the coils and injectors.

Go to motorcycle doctor.com and download the schematic.

the computer back up to it, I noticed I was not getting a RPM reading and was getting a CKP sensor error which meant it was not getting the correct counts. I took the flywheel cover back off to check the air gap. Not much movement but moved it as close to the inside as possible. I then compared the eBay special to the original and noticed that the wire colors were opposite of each other. I put all back together and it still wouldn’t start. Just for the heck of it I switched the pins on the harness coming from the sensor and BOOM! She fired right up! I would have never thought that the polarity of the sensor made a difference but it does. Just something to think about when you buy aftermarket parts.

Ok guys, my turn... Working on my neighbors 2017 Massimo MSU-500. Initial complaint was it would start and run for about 10 minutes and the just die. He replaced the fuel pump and still had the same issue. I stopped over one day to look at it and saw that it had codes flashing on the dash; 505, 336 and 337. We decided to get a new stator/crank sensor. Took it apart installed the new stator/crank sensor and nothing. It won't even start. I checked the pins on the crank sensor plug and one was in the wrong place, so I repinned it and it still won't start. I double checked the connectors and all is good. I checked the wires from the ECU to the coil, good. It appears to have spark every once and awhile but not enough to start. I replaced the coil with a known good one and still nothing. I bought the cables and downloaded the ECU hardware and everything looks good. I pulled the timing cover back off to check the flywheel keyway, it is good. I checked the timing and timing chain, good. I checked the valve lash, good. I have to put it back together but just wanted to post in case there is something else I should check before hand. I checked the 9 pin connector and it is clean. I have battery voltage on the purple wire and pins 15 and 18 on the ECU. I pulled the air filter off and I am going to put a new plug in it just for the heck of it. What ECU inputs would prevent it from starting? Why would it now not start at all after replacing the stator/crank sensor? It has to be something simple. Any help would be appreciated.