Comparison of Q-matic/HS142 to HondaGX50/FD to Robin/CVT

Mike St

Active Member
Jun 16, 2008
Well the bikes have been prepared and tested side-by-side, and
the results are in:
Bike #1: HS 142F/Q-matic drive with 72 inch sprocket, 7/8 inch pipe,
and carb with fuel jet drilled out to 0.026 inches, and holes drilled into
the carb cover.
Bike #2 is a Thatsdax Friction Drive with 1.25 inch roller, and Honda GX50.
Bike #3 is a Robin 35cc with an pocketbike cvt. This bike features a double
right sided drive.
The Robin with the CVT performed poorly. Although it could start from a
stand-still, it was very sluggish off the mark, and top speed was about
18mph. The CVT seemed to rob too much power from the engine. I thought
the CVT would make the bike move off quick, but it didn't happen. My
conclusion is this combination is not effective, very poor performance.
The friction drive with the Honda GX 50 accelerated well once it got
going, and the top speed with the 1.25 roller was about 30mph. The
problem was it was difficult to make a smooth transition to power the
wheel from a stand-still. It requires pedaling from a start, and learning
how to smoothly apply power. I would say this combination is
not good for urban stop and go traveling. Better for open road long
distance. OK, but not the best.
Bike #3 the HS142F and the q-matic drive and 7/8 inch exhaust pipe
and opened carb did the best. In previous tests, this combination was
sluggish, but after opening the carb jet, it seemed like the bike gained
about 15-20% more power. No need to pedal from a start, and
acceleration was quick. Top speed about 30mph. This combination was
as close as possible to having a real transmission. Great for urban and
long distance biking. I'd say the the Grubee 4g belt drive would probably
perform about the same with all the modifications I made on this bike.
That's all folks!!



Well-Known Member
May 26, 2008
Problem with the soobie is it's under powered for that application. Any friction drive in my opinion should be pedaled from the start to help save wear on the tire. Excellent comparison for your bikes. That HS setup does that back sprocket have 200 teeth? That's for pure torque, smaller and you could easily hit 40mph. Great bikes, I'm envious.

Mike St

Active Member
Jun 16, 2008
The back sprocket has 72 teeth, set for torque and 30mph. I
don't think a motorized bike should go over 30 - too dangerous.
I think one could learn how to apply power with an FD for a
smooth start. It's possible but not ideal.

MotorBike - Wayne

Well-Known Member
Apr 23, 2020
Thats not the top speed on the 26in. Top speed is 38.9mph. Its seems to like 22mph, Its got that sweet buzz to it = Happy zone


Active Member
Jun 14, 2009
You would be much happier mounting the Honda GX50 on the CVT drive and then mounting the Subaru on the Friction Drive. The CVT needs more power than the Subaru puts out.

Mike St

Active Member
Jun 16, 2008
Sounds like an idea but won't work. The GX50 is designed
as a trimmer engine and does not have mounting points
on it. The Huasheng 142F would work, but then there
would be too much weight on the back of the bike. The
beauty of the GX50 is it is very light, so it works best
with a friction drive.


Active Member
May 6, 2020
Don't come ride in our area,,, 22 mpr won't work since there will be nothing left of your bike and clutch...

Steep up hill climbs,,, massive wash-outs,,, bolders that will bust the rims,,, and 100's of downed trees to clear on most of these trails...

If a person can pull off 7 too 9 mpr you'ld be golden,,, 20 to 22 mpr tops on the endless miles of wash board would deffinaly let you know how the double wall rims and bike frame are going to hold up...

Yes that 30,,, 40,,, 50 miles per hour would be nice in the world of pavement,,, but that aint going to happen in our area,,, its black dirt,,, kow pastures,,, boulder mountain trails of dry if it doesn't start raining...

Swamps and boggs,,, beaver dams,,, swamps then another mountain wall after that,,, the whole day is a work out...

So,,, what speed might work for 1 person won't work for the next...

It really boils down to each person riding style,,, their wants and needs,,, and the ground they cover...

We have to suck it up when we roll into the flats,,, it would be awesome to pin-it across those valleys of endless,,, but it aint going to happen...

The box canyon will be there when we get there,,, is it wizer to get there fast to go on foot from there on in,,, or get there slow and continue going forth on the wheels you have...

Thats how it plays out in our books...

30 mpr and faster is fun,,, same can be said for 7 to 9,,, it depends on how much the unit and person can take...

I'm glad that our builds are based on farm operations and mountain outings...

Life at 14.7 mpr is good when it happens...