Hawk engine swap to Zongshen PR250/300

[Dusman]

This thread is for those who are interested in installing the counterbalanced, 6 speed Zongshen PR250 or PR300 engine into their carbureted Hawks.

I just installed the Zongshen PR250 6 speed counterbalanced engine in my Hawk this past weekend. It shares the same bottom end/crankcase as the PR300. These engines will fit the Hawk, but certain necessary and significant frame modifications need to be made in order to make it fit inside the Hawk's engine bay and to run the engine with the carbureted Hawk's wiring harness.

A. Some engine mounts have to be cut out and re-welded back in. There's two ways to do this:

1. You either have to cut out the lower front mounts, install the motor into all of the other mounts (except the upper mounts, more on that later...). Then, weld the lower front mounts back onto the frame with the lower front mounts *attached* via the bolts to the PR250 engine while you weld it in place. Then, you'll have to remove the engine again, finish welding the lower front mounts in from the top of where the mounts come into contact with the frame tubes, re-paint that area, then re-install your PR250/300 engine. Also, for the upper front mounts, the ones that require 3 bolts, you'll have to re-make your own mounts with 1/8" thick flat steel (3" width) purchased from the hardware store. See also # 3 below. That's the method I chose.

2. The second way is that you can cut out the rear middle mount tange on the right side that comes off the rear cross member of the frame to get the engine in the bay. Second, you have to elongate the holes on the lower front mounts. Now, your engine will fit in the engine bay, but if you re-weld the rear middle mount's tange back to the frame, I'm not sure you'll be able to easily get the engine out again. With the method I used above (1), you can get the engine in and out as needed, though it takes some work as it's tight in there!

3. This last part isn't necessary, but for me, I did it as I felt like I need the extra wiggle room for the engine. Where the front downtube of the frame comes down and splits into the dual spar frame configuration, where the downtube continues straight and slightly extends beyond the tubes on either side that make up the "spar", I cut that out with angle grinder to allow more room for the counterbalancer at the front of the engine. Two other fellows in the Hawk 250 FB group that installed this engine didn't do that, but apparently it wasn't necessary for them. For me, it significantly helped provide more room for the engine's counterbalancer without sacrificing frame integrity.

B. Now, to get the PR250/300 to run on the carbureted Hawk's wiring harness, you'll have to remove the stator, stator wires, and flywheel from your Hawk's stock CG 250 motor and install them into your PR250/300 engine. While you could theoretically avoid having to do this by completely changing your electrical system over to a GPX FSE 250e or Templar X 250 wiring harness & system, good luck finding one of those since as of the writing of this post, they have been for me, totally unobtanium.

It's a lot of work, but it's worth it for me to have the 6th gear, the counterbalancer, and the ability to ride comfortably at 60-65 mph without having to lose that low tractor-factor with first gear for off-roading.