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100 MPH ON A 175

By Matt Cuddy


The F7 175cc Dual Sport was built by Kawasaki from 1971 to 1976, and while the motorcycle could be mistaken for the 125, you couldn’t mistake the power the 175 had over its smaller brother.

Like all Kawasaki small bores of the time, the F7 utilized a rotary valve induction system, the only induction system on a two cycle motor not governed by atmospheric pressure, a true “timed” system. The rotary valve design gave the 175 quite a bit of power, and put the 175 into the ranks of 250cc dual sport bikes of the time, 21 horsepower at 7500 revs per minute.


A 1972 F7, just like mine...

And those weren’t “peaky” horses either, as the Kawasaki F7 could grunt with the best of them, and still rev out to a very respective seventy mph on top. The F7 also had some innovations such as the Hatta front fork that supposedly gave over thirty different configurations of axle placement, spring rate and rake settings. While that looked good on paper, the Hatta forks (like the forks on about every Japanese trail bike of the time) were junk, and most riders opted for the axle set in the center, and the preload cranked all the way up. Heavier 15 weight oil helped, but not much. The rear shocks kept the tire off the fender, but that was about it. A handler it wasn’t. It was also on the portly side, tipping the scales at around two hundred and fifty pounds.

1974 F7. Notice the Hatta forks's axle settings

But oh Lordy, what a motor. That little rotary valve 175 cee cee motor put out some serious cajonies, and many times the F7 embarrassed a much larger real dirt bike by smoking it up a sand wash, or across a dry lake bed.

Not to say the F7 didn’t have its faults. Control levers were brittle, and would shatter if you looked at them wrong. The rear hub was weak, and would fail at the bearing mounts, and bring the bike at an abrupt halt.

Excess flashing in the center cases would break off, and get stuck in the gearbox, or primary gears. This would cause disconcerting times for the rider, as the motor made tap-tap-tapping noises with the occasional loud “CLUNK” and a piece of aluminum got stuck between the gears somewhere inside the cases, and then spit out again. Didn’t seem to cause any problems, just made annoying noises that would drive you nuts, trying to figure out what just happened.

Because of the enclosed carb, and the air filter opening under the seat, the F7 was almost amphibious, and could be driven through water crossings that would drown lesser machines. It also had Kawasaki’s CDI ignition system, that made points…err..Pointless.

The 175 used Kawasaki’s version of an automatic oiling system that injected oil into the intake track of the motor, and bathed the crank bearings too. This made removing the system almost impossible, since you would have to modify the cases to allow the mixed gas/oil combo into the mains. Thankfully, the system was very reliable, and seemed to meter the oil a lot more precisely than Yamaha’s Autolube (which ran at about 15.1 most of the time).

I owned a 1972 F7, purchased from World Cycle used, after my RT3 got stolen. The bike sported Carsile flat track tires, and was used as a set bike by Paramount pictures. One test ride up and down Sunset blvd, and I was hooked, the bike seemed to be as fast as my erstwhile RT3, but how was that possible? After parting with my hard earned three hundred dollars, The F7 was mine, and I was back in bizness again.

After a few months of hard riding, the rear hub failed, and I was forced to look for a replacement. Kawasaki wanted $150.00 for a new wheel assembly, so I purchased an AT1 rear wheel from Johnson & Wood Salvage that almost fit perfect (with some ½ “galvanized pipe spacers made up special). Now I didn’t have a sprocket lying around handy, so the 150 Dream Cycle parts bike was cannibalized once again for its 38 tooth rear sprocket, much too small I thought…

The tiny rear sprocket transformed the little 175 into a rocket ship. Top end was well over one hundred miles an hour, and the damn bike still had enough grunt for single track work. I was amazed, as I’d pull 500cc bikes on top end, and all they’d see was the F7’s tail light disappearing into the night. My buddy Rick’s 350 Honda (that use to take my 360 on top) was now dead meat at anything upwards of 80 mph. I was just gone. Bye bye. All my dirt riding buddies were smoked on fire roads, and dry lakes, as the little 175 whooshed by them at crazy fast speeds. The best mod I ever made to a motorcycle.

But alas, all good things must come to an end, and right before I joined the Navy in 1976, the Kawasaki was stolen from out front of my girlfriend’s house. The police found what was left of it a few weeks later, abandoned in Griffith Park missing everything but the frame and front forks.

But for a while it was the fastest 175 in Silverlake, if not the Earth. Just another small rotary valve Kawasaki with insane power, seemed Kawasaki had that formula down.