Engine swapping: 550 on a KZ650 frame?

One of the bike I looked at before buying mine was a 78 KZ650 that was absolutely beautiful, with low mileage, but a bad engine and transmission. It dropped a valve, and the guy was honest enough to tell me he'd had no third gear, and there was a ton of "grinding" when in other gears. I passed on it.

The other day, I ran across a wrecked 550LTD (I think it's an '82) with less than 5000 miles on it. The price is really low, and the guy with the KZ650 called me last night and offered me the bike for a ridiculously low price. I can pick them both up for 250, maybe less if i negotiate a bit.

I'm wondering if the 550 engine will bolt to the KZ650 frame. If not a direct bolt-on, what would it take to fit it? I realize anything is doable, but, could it be done with a reasonable amount of effort, without butchering the KZ650?

Post edited by: seanof30306, at: 2007/07/28 11:43

As long as the 550 is chain driven, it can be done with little to no mods as far as mounting goes.
However the electronics (reg/rec, ignitor, etc) from the newer engine will need to be swapped in, which likely means using the entire wire harness from the donor bike also.

Why not just rebuild/restore both bikes?
Complete KZ650 engines pop up on eBay frequently, and are usually in the $100 to $200 range.

Post edited by: RetroRiceRocketRider, at: 2007/07/28 12:33

I set a search up for a 650 engine, didn't see any complete ones. The forks, frame and wheels are all bent on the 550, and the tank is caved in. I don't see it as a candidate for a rebuild. Just figured since they're both nearby and available cheap, it would make sense to make 1 bike out of two.

Sometimes complete engines can't be found anywhere, then all of a sudden it seems as if everyone is listing them for sale at once!
Patience and frequent searching will eventually locate you a good donor engine.

I didn't know the 550 was all banged up. :pinch:
But knowing that now, and if it were ME, I'd steer clear of it unless I already had another 550 rolling chassis to stuff the (good?) engine into.

Even though most swaps are done for the sake of having a larger engine/more horsepower, it's not impossible to swap the smaller engine into the 650 frame like you are considering.
But just be aware that there will be a lot more work involved compared to a direct engine swap, since the previously mentioned electrical components will need to be swapped in as well.