85 gpz550 engine swap

I have an 85 gpz550A2 complete bike minus the motor. What engines are a direct bolt in for my frame. As i am having issues finding a suitable 550 engine

If you include engine mounts, carbs, air boxes, and ignition, only Zx550A motors will be a direct swap.

Any chain-drive Kz550 will fit, but the motor mounts could be different so you might have bolt and mount swapping to do. I think the Zx might have even eliminated one of the mounts that was used on earlier models, but I can't swear to that.

Carbs might not swap over. The airbox from those other models will not fit the frame and your airbox might not fit the early carbs. The first gen motors use smaller intake ports with closer bolt spacing on the carb holders so you might be stuck using the smaller mechanical slide carbs if you get a first-gen motor. They include the 80-82 Kz550A1-A3(standard), the 80-83 Kz550C1-C4 (chain-Ltd), and the 81 Kz550D1 (dual-shock Gpz).

The second gen motors using CV carbs will be much easier to swap in terms of carbs. They can use your existing carbs. Those motors are the 82-83 Kz550H1-H2 (Gpz) and the 83 Kz550A4 (standard).

All of the earlier motors will use a mechanical-advance ignition. Your motor uses electronic-advance which uses a different igniter and pickups. Your pickups won't just bolt into an older motor because the casting is different, but it's not difficult to modify. You just have to cut away some aluminum and then you can use either system. (The coils between systems are interchangeable).




If you can find one, I think a Zephyr 550 motor will also be an option, but they are pretty rare. That is the Zr550B mentioned in the animated graphic.

That is an awesome graphic.