Recent Posts  By   (Read times)

After riding with it for about 3k km, I found my front tire is about halfway through the thread, so good enough for a good 5-6k km.
The rear tire surprisingly is in better condition.

I've been thinking as to where to place this bike; where it's best used for.

When I look at the following data (see below) I can only conclude that this bike is not optimized for riding anywhere.
The engine is too small and the gearing too small to be optimally used just about anywhere,
Mechanically it's impossible to gear the bike correctly, and it's really missing a 5th gear!
In final gear (4th) following data is true:

With a 41T your useable speed is between 20 and 40MPH. Torque is very high, too fast shifting, much, much too high revs, ok gas mileage.
With a 36T your useable speed is between 23 and 47MPH. Torque is normal, fast shifting, still very high revs, good gas mileage.
With a 34T your useable speed is between 24 and 50MPH. Torque is low, perfect shifting, high revs, excellent gas mileage.
With a 31T your useable speed is between 30 and 55MPH. Torque is very low, long gears, less high revs, superb gas mileage.

Optimal speeds for each sprocket is between the lowest useable speed and 5MPH faster, meaning:
41T = 20-25MPH
36T = 23-28MPH
34T = 24-29MPH
31T = 30-35MPH

This because the revs are lowest there, MPG is the best, and the bike is just made to cruise at these speeds all day long.
Because the front sprocket is not changeable (to a larger one), I can not gear the bike correctly.
The perfect rear sprocket would bring the useable speed between 35-40MPH, or it would be a 23T sprocket.
With a 23T sprocket, the engine would rev best at 35-40MPH; however:
1- It's mechanically impossible to go so low
2- The bike would have too little torque to use 4th gear.

For this to work the engine should be at least a 250cc engine, to pull the load, or the bike needs a 5th gear.

So from gearing perspective, this gearbox is not tuned to work well with this engine in the city, on the highway, nor in the suburbs.
The city, because the gearbox is weak, and can't stand the industrial use of start-stop traffic in city.
The highway, because the engine is too weak to pull anything faster than 55MPH at a constant speed.

And though it is possible to use this bike in the city, on the highway, and in the suburbs, that 'perfect gearing' for suburbs is not possible on this bike.
Which classifies it somewhere between city, and suburbs. An area where the speed limit is 25-30MPH, and there's not too much start-stop traffic.
Know any area like this??



Since it's impossible to get a good gearing on this bike, that would fit either one of the three environments (city/suburbs/highway) and since the engine is too small in displacement, has too low torque, we can base our calculations to at least make it useable in the torque area (acceleration), rather than base it on perfect RPMs.

The minimum torque needed to plow through traffic would be with a 33T sprocket, in my recommendation.
I'm running a 31T, but in order to accelerate at moderate speeds, I need to work the engine to 80% of the throttle.

A 33T is the absolute minimum to put on there imho, but anywhere between 33-36T is good. 33T if you're lightweight, and ride alone, on level ground. 36T if you're traveling with 2 people, or are heavy weight, or travel with luggage, or have steep hills to climb.

With a 34T, the most optimal speed for this bike is well below the minimum speeds on suburb roads (35MPH); which gives 2 options:
1- Either you use the bike for the city, in start stop traffic, which it is an excellent bike for the money, but the gearbox is not upto the task of daily shift abuse of the city
2- or you run the bike on the suburbs with a 34T, in a little higher rev range (3-4k RPM).
3- Or you install a 31T sprocket, like I did, and the bike works fine in 35-40MPH traffic, but there's almost no acceleration in 4th gear (takes forever to get upto 50MPH).

This leads me to believe, that for practical purposes, if you're living in the suburbs, 35-40MPH roads, with these gearings, you can do with a larger engine; because it's sometimes better to run a 250cc at 2500RPM to maintain 40MPH, than to run a 125cc at 4k RPM. Gas mileage difference should be minimal, as long as the 250cc has tall gears, but there's plenty of torque left to accelerate, which the 125cc does not have.


The 125cc engine is good for the city, if they only paired it with a good gearing, rather than the crappy 4 speed step through gearing.
The problem with the step through gearbox, aside from being weak and not upto daily abuse, would be that the gearbox is pretty annoying when approaching a red light.
The gearbox works as follows:
N > 1 > 2 > 3 > 4

It does not allow shifting from 4th gear into neutral, unless the bike is standing still; which gives the following problems:

Prior to approaching a red light, one has to determine when one will arrive to a stand still, and how much time one has to finding the right gear and move on.
If the light just turned red, the right method would be to roll to a stop, shift from 4th gear to N, and into 1st gear when it gets green.
Don't leave the bike in gear when idling, as the clutch rubs, and wears out this way. You can feel it, when in 1st gear, the bike tends to pull forward a bit.

A second scenario could be that you approach the red light but before you come to a full stop, the light turns green.
In this scenario it's impossible to shift from 4th into neutral, and thus you need to shift back to 3 > 2 > 1 st gear (depending on how fast you're still going).
Usually anywhere below 5MPH is 1st gear, 10MPH 2nd gear, and 15MPH 3rd gear.
When downshifting, from 4th to 3rd, to 2nd, the gear that you need to be in, will jolt the bike gently, meaning the clutch will be disengaged when shifting from 4th to 3rd when going only 8MPH. When downshifting to 2nd gear, the bike jolts gently, and when accelerating, you'll find the gearbox grips like it should.
If you would have stayed in 3rd gear, you'd notice that the engine is keeping RPMs at a constant, while the bike is accelerating. This is the clutch gripping, and is actually pretty bad. it's possible, but very bad to start from a standstill in 2nd, 3rd, or 4th gear, as you will wear out the clutch in no time, could possibly even burn the clutch.
When instead of shifting from 2nd gear (where you felt the gentle jolt), into 1st gear at 8mph, the bike will jolt heavy.
If it rains you could lose grip on the rear wheel, lose balance, fall off the bike, or destroy the gearbox when downshifting more than 1 gear too much; unless you compensate by revving up the engine while downshifting the gears, which is V E R Y hard to do if you want to do it correctly.

The safest downshifts are when the RPMs are low; or, also called 'tardy downshifts', meaning wait until the clutch disengages from a gear due to low RPMs before downshifting

So those 2 scenario's make the gearbox not particularly user friendly, especially not in the city where a lot of shifting would be necessary.

For the city, they had better equipped this bike with a CVT.
For the suburbs they had better equipped this bike with a larger engine (at least 150-200cc), and a 15/31 or 17/35 gearing, or a 15/36 gearing with an extra 5th gear.

For the highway, you'll need a 250cc or more.

I ride not only for fuel economy measurments, and seeing how the bike responds to different types of gas, I also ride to think. While riding, I'm thinking about a lot of things, including sprockets and cheap mods, as well as future motorcycle purchases.

I also ride the crap out of some of my vehicles just to post here when the darn thing finally gave up the ghost.

That being said, most of the time I'm easy on the throttle. I prefer cruising over racing, and good fuel economy numbers.
Also racing will wear out engine, brakes, and other parts much faster.

So cruzin' it is!

Perhaps start out with some really thin oil, and change it after 50-100 miles.

I mean, it's aluminum, and carries heat. I don't know if it gets any hotter than a standard steel muffler.

The photo is mirrored. Exhaust usually is on the right, not left side.
Exhaust is aluminum, good performance exhaust for a 150cc. It still has naked steel parts that will rust, but the muffler material is mainly aluminum and won't rust easily.

Don't know if it will get hot or not.

Alright, we can still thank the Chinese for giving us a cheap way of transportation, that for the majority of us don't break down (if it's kept stock).

I've seen vids of a vespa dealer trying to show how crappy chinese vespa clones where, by videofilming how the belt broke while accelerating.

He doesn't say if the performance variator wasn't putting extra pressure on the belt, or the engine had a BBK, and the extra torque was over the specs of the belt's specs...
Anyway... A lot of chinese bikes break because of incorrect modding. Making them faster, and expecting them to live just as long is not... correct...