Step 4: Modifying the rake angle of the original HCF-305:
The rake angle of the original HCF-305's front wheels are backwards!
Look carefully at any bicycle, or motorcycle, and you'll notice that the front wheel slants well forward of the handlebars. A typical motorcycle, for example, has a positive rake angle of about 30 degrees. The rake angle of a well designed bicycle, or motorcycle, provides inherent stability, so that the rider can easily ride without any hands on the handlebars, yet continue in a straight line.
But with the HCF-305, the problem can be corrected. The engineer who designed the HCF-305 seems to have provided for a good, positive rake angle, but, somehow, down the line, the front wheel suspension was reversed (backwards). A quick examination underneath will reveal that the front wheels need to be removed, leaving the brakes in place on the wheels. Both wheels are held on with standard right-hand thread bolts, with 17mm heads. But be sure to unscrew the tiny lock-screw, on the steering arm, first. Then the entire front swing arm / headset bearings / steering arm joint, on each side, needs to be removed and switched left and right with each other (leave the shock absorbers in place on the frame). The steering arm, underneath the headset bearings, (also holds the wheel axle bolt), will need to be installed upside down this time.
But first, the original M10-1.5 pitch headset bolt needs to have an additional 11mm of thread cut into it to properly fit into the now upside down steering arm (a simple handyman project). The brakes (actually a drum, mounted permanently on the wheel hub, encircled by a removable steel compression band), are designed to primarily stop forward motion, so will have to remain on their original sides and orientation. After the adjustments, the front wheels will extend forward an inch or two, and the steering tie rods will now assume a more natural, horizontal position. My HCF-305 now glides over bumps and rough roads much more smoother. Changing the HCF-305's front wheel suspension to a proper rake angle will reduce stress on the steering headset bearings, so that they will now absorb bumps, at the angle they were designed to do, and pass the shock of the bumps directly to the shock absorbers, which will also now be in a better able to dissipate those impacts.
Modifying OEM 22" handlebar to a 29" Longhorn handlebar:
The HCF-305, being a "scooter", does NOT have pack and pinion steering. This means, that at full cruising speed, the HCF-305 experiences a slight loss of steering control, especially when riding over rough paved surfaces. I initially planned to install a hydraulic steering dampener in the undercarriage, but simplicity dictated that adding 4" extensions to each end of the handlebars should provide the proper leverage, a well as a natural steering dampener effect.
The steering system of the HCF-305 is well built, tight, and secure. But the turning radius is just too tight for comfortably running the vehicle at full cruising speed.
I machined down two 7/8" diameter hardwood dowels, 7-1/2" long: 4" @ 7/8" diameter + 3-1/2" @ 3/4" diameter. The inside of the handlebars were degreased and the wooden extensions were glued into place and then marine varnished.
But the above steps are not a cure-all. My HCF-305 now leans slightly out of the turn, and tends to slightly veer left and right, from a straight line, while driving, but the the over-all handling of the vehicle is definitely improved.
So feel free to alter the front-end suspension, but at your own risk.