I am matching a 1991 suzuki gs500 frame to a much newer engine (it has the oil radiator cooler on it).  I have the engine number.  I have mounted the engine in my frame, but many harnesses don't match.  My main concern is the stator plugs/harness don't even pair up in the number of cables. 

So what I'm thinking of buying a newer harness and just swap out the old '91 wiring harness from the frame.

I don't want to buy the wrong harness to the actual engine I have.

Where can I search what year my engine is?

Engine Number: M504-137190

Thank you very much for the help!

Stator: The old ones had 3 barrel connectors that went into the harness, and came out as a 3 pin connector to the regulator. Newer bikes eliminated that and went directly to the regulator. So just run your 3 pin connector from the stator to the regulator. Ignore that intermediate run of wire in the harness.

TIMING: You will need to use the timing rotor from your older motor and the dual pick up. It is a direct swap. The newer bikes had a single pickup and a smarter ignition box. Older bikes had 2 pickups and a dumb ignition box. So makethat swap. If you need an older rotor and pick-up, post a want-to-buy. Many of us have extras.

CARBS: Newer motors (2001+) had different carbs and the carb boots on the head are different. Older carbs will fall out of the carb boots if the newer ones are there. You need to use the older carb boots. When you swap carb boots, replace the o-rings as they will be hard and flat after all these years.

NEUTRAL SWITCH WIRES: There will be 2 extra wires from the neutral switch. Ignore them. They are important only for the newer ignition control unit from 2004+ models. If you do not have an extra connector from the neutral wire, then your motor is 2001-2002. If the extra is there, it is 2004+. All motors 2004+ are the same.

WIRING: You do not need to change the harness. See notes above regarding the stator wires. Changing the harness means changing hand controls due to different connectors and buying the new ignition control unit. The flasher might have to be changed. I have seen 2 or 3 different connectors on the turn signal flasher units but those are cheap.

PS: Assuming you are doing an engine swap in what was a running bike until the motor died. Correct?

Just out of interest I would also like to know if there is any way to date an engine from the engine number, mine had a different motor in it when I bought it. Thanks

http://gstwins.com/gsboard/index.php?topic=57564

Thanks