Honda CB twister

@zaveri-5TD6Sk • Oct 26, 2024

Oct 26, 2024

990

last year my friend got his new bike, a Honda cb twister, and he invited me for a test-drive .

the snazzy looks of the tank and cowl were appealing, but what really annoyed me was the gearshift. the shifter is a single-sided pedal, with a sophisticated shift pattern and above all it was more soft touch than a touch screen phone.

But then i was surprised told me that the gearshift wasn't much of a problem, because the vehicle started in any gear, including the top gear !

And as i rode it i saw that for myself. there was absolutely no need to shift to neutral, before starting the engine. all that i had to do was pull in the clutch lever, press the self-start switch , and after the engine came to life, just release the clutch and simultaneously twist the throttle , and that was it , the bike started moving smoothly.

This entire thing amazed me. what went in to designing the gear box, so that the vehicle can start even in the top gear. what do you guys feel about it ? are there any other bikes on the road, which have this same design flexibility ?

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zaveri

@zaveri-5TD6Sk • Jul 20, 2012

no replies here ?
SYED BASEERULLAH

@syed-baseerullah-1sAVGB • Jul 20, 2012

i too have got my CB twister and i think its familiar with all newly manufactured bikes like in case of YAMAHA GLADIATOR
IT is an electric motor that initiates rotational motion in an internal combustion engine before it can power itself.

The modern starter motor is either a permanent-magnet or a series- or series-parallel wound direct current electric motor with a solenoid switch (similar to a relay) mounted on it. When current from the starting battery is applied to the solenoid, usually through a key-operated switch, it pushes out the drive pinion on the starter driveshaft and meshes the pinion with the ring gear on the flywheel of the engine.

The solenoid also closes high-current contacts for the starter motor, which begins to turn. Once the engine starts, the key-operated switch is opened, a spring in the solenoid assembly pulls the pinion gear away from the ring gear, and the starter motor stops. The starter's pinion is clutched to its driveshaft through an overrunning sprag clutch which permits the pinion to transmit drive in only one direction. In this manner, drive is transmitted through the pinion to the flywheel ring gear, but if the pinion remains engaged (as for example because the operator fails to release the key as soon as the engine starts), the pinion will spin independently of its driveshaft. This prevents the engine driving the starter, for such backdrive would cause the starter to spin so fast as to fly apart. However, this sprag clutch arrangement would preclude the use of the starter as a generator if employed in hybrid scheme mentioned above; unless modifications are made.

This overrunning-clutch pinion arrangement was phased into use beginning in the early 1960s; before that time, a Bendix drive was used. The Bendix system places the starter drive pinion on a helically-cut driveshaft. When the starter motor begins turning, the inertia of the drive pinion assembly causes it to ride forward on the helix and thus engage with the ring gear. When the engine starts, backdrive from the ring gear causes the drive pinion to exceed the rotative speed of the starter, at which point the drive pinion is forced back down the helical shaft and thus out of mesh with the ring gear.

An intermediate development between the Bendix drive developed in the 1930s and the overrunning-clutch designs introduced in the 1960s was the Bendix Folo-Thru drive. The standard Bendix drive would disengage from the ring gear as soon as the engine fired, even if it did not continue to run. The Folo-Thru drive contains a latching mechanism and a set of flyweights in the body of the drive unit. When the starter motor begins turning and the drive unit is forced forward on the helical shaft by inertia, it is latched into the engaged position. Only once the drive unit is spun at a speed higher than that attained by the starter motor itself (i.e., it is backdriven by the running engine) will the flyweights pull radially outward, releasing the latch and permitting the overdriven drive unit to be spun out of engagement. In this manner, unwanted starter disengagement is avoided before a successful engine start.
zaveri

@zaveri-5TD6Sk • Jul 22, 2012

Okay, but i would like to know about its gearbox and not the starter motor.
PuneetVerma

@puneetverma-cfL67U • Aug 2, 2012

Even Discover 125 with self start, can be started in any gear as long as you press clutch while starting. I think any bike with self starter can be started with this way. But you have to press clutch so that while starting you don't have drive shaft engaged with gear box. In these types of bike, there is nothing new with gearbox as clutch is dis-engaged.
zaveri

@zaveri-5TD6Sk • Aug 2, 2012

pverma
Even Discover 125 with self start, can be started in any gear as long as you press clutch while starting. I think any bike with self starter can be started with this way. But you have to press clutch so that while starting you don't have drive shaft engaged with gear box. In these types of bike, there is nothing new with gearbox as clutch is dis-engaged.
Bikes like super splendor and splendor pro do not start this way i think.
Sanoj Rajan

@sanoj-rajan-wTjQA9 • Aug 4, 2012

zaveri
Bikes like super splendor and splendor pro do not start this way i think.
The thing is that, to start a bike, i.e., to bring it into motion from rest, what we require is torque.

Before jumping into discussion, let me clear some facts. When motion is transmitted from a larger gear to a smaller gear, the speed increases. And when motion is transmitted to a larger gear, speed decreases.
But speed and torque is inversely proportional to each other. When one increases, the other decreases.
Sanoj Rajan

@sanoj-rajan-wTjQA9 • Aug 4, 2012

zaveri
Bikes like super splendor and splendor pro do not start this way i think.
In a gear box, the 1st gear is the largest gear. And then the size decreases as we move towards the top gear. Its because, to bring the vehicle into motion from its rest condition, lot of torque is required. Thus large gear is used (as mentioned in the previous reply). And once the vehicle is in motion, less torque is required to push it further, thus smaller gears will do.

Coming to your question, what happens in such bikes is that, all the gears are designed such that, even the top gear will generate enough torque to put the vehicle in motion. Thus there is not much problem, at-least nothing that u can notice at a short run.
zaveri

@zaveri-5TD6Sk • Aug 5, 2012

Sanoj Rajan
Coming to your question, what happens in such bikes is that, all the gears are designed such that, even the top gear will generate enough torque to put the vehicle in motion. Thus there is not much problem, at-least nothing that u can notice at a short run.
that is what i thought as well. but then doesn't that mean that the size of the top gear will have to be greater. doesn't that mean that the purpose of having a first gear is defeated.
Sanoj Rajan

@sanoj-rajan-wTjQA9 • Aug 6, 2012

As u have tried starting the bike in all the gear, you might have come across some difference in all the gears.
When u start in first gear, u don't have to go hard on your accelerator.
But on top gear, ...

I hope you got the idea.
zaveri

@zaveri-5TD6Sk • Aug 6, 2012

Sanoj Rajan
As u have tried starting the bike in all the gear, you might have come across some difference in all the gears.
When u start in first gear, u don't have to go hard on your accelerator.
But on top gear, ...

I hope you got the idea.
Yes i did . but then did you notice that splendor plus never starts in the 3rd gear. it stalls no matter how carefully you play with the clutch lever.