Yes you can do that but I ordered an adapter on eBay a few years ago when I converted mine.

 

Go with a 6 pin round to 4 flat adapter. Since your vehicle side does not have that 6th center pin, it will still fit in the socket. It may not give you all the functions in the trailer lights but would work in a pinch.

https://a.co/d/bvAwRMf

 

You should use an isolator and converter, the wing’s lighting system doesn’t like to be overloaded and the converter will insure everything works correctly on the trailer.

 

Do this you will not regret it.

 

Happy Rob,
You've been given some choices. All of which are fine and will work. This IS simply a choice thing. I'm sure you're aware of the logistics but in case not, it's pretty simple. In your basic 4-wire scenario, you typically have:

1. White (or possibly black) as GROUND
2. Green for RIGHT TURN
3. Yellow for LEFT TURN
4. Brown for RUNNING LIGHTS (also sometimes labeled as "T/M" or, Tail/marker

The 5th wire for most 5 wire applications, especially when it pertains to motorcycle trailers is for BRAKE LIGHTS only.

If your trailer has only TWO LIGHTs on the rear, one right and one left, you have what's called combination BRAKE and TURN in each light. Hense, the four wire setup will actually be:

1. White (again or black) as ground
2. GREEN would now represent BRAKE and Right turn
3. Yellow would now represent BRAKE and Left turn
4. Brown for running or T/M

Scott

 

You need to either make an adapter with diodes to allow for a 5 to 4 plug, or buy a 5 wire to 4 wire adapter and wire the 5 side to a male plug that will plug into the bike's plug, and the 4 wire side into a 4 wire plug.

Easy to do, just have to buy a male 5 wire plug and the female 4 wire plug and a couple of butt connectors.

If you don't do the above - or find a true 5 to 4 wire adapter that incorporates the necessary elements - you will end up with only running lights and turn signals. A cheap 5 to 4 adapter only connects the wires discussed in @FIRE UP post 5.

 

Happy Rob,
Since this post is a few days old, you may have already completed your bike/trailer wiring setup. If you haven't, and since your bike is wired with a brand new 5-pin round, In my opinion, for whatever it's worth, would be for you to simply cut the 4-pin flat off the trailer and purchase the 5-pin round mate for your new bike end plug. Then simply mate up pin to pin and wire to wire for a neat, clean and well done NEW system. That way, there's no adapters, no additional potential problems due to too many connections that are not needed. I like clean and simple.
Scott

 

I found an adapter at princess auto Perfect 5 wire to 4 wire adapter and it’s working great. Tons of room in rear of wing to tuck the wires away