The Gentle Art of Shifting a Bajaj Scooter

and maybe

With the ever-increasing number of scooters coming to America, the Bajaj Legend and Chetak scooters hold a unique position; they are the modern scooters available with 4 speed manual shift transmissions. While the rest of the pack is taking the "twist and go" route, we have a scooter that challenges our skills and rewards us with absolute control over shifting and a well-deserved sense of accomplishment.

For those who find "twist and go" the perfect solution to their scootering adventures, please stop here. You will probably be bored by what is to follow.

For those of you who are intrigued over the mysteries of how engine, clutch and gears work in harmony to propel you over hill and dale, or if you want to shift your scooter without making embarrassing clashing of gears noises… or if you just can’t stand to be shiftless…. read on.

The scooter swami did not choose the title of this article lightly. Shifting is an art and it is performed best when done in a gentle manner. While millions of people around the world have learned the rote process of how to shift their manual transmission scooter, few understand what’s going on inside, and even fewer perform the task in a manner that is efficient and kind to the interior workings of the machine.

While we will save for another time the matter of whether the machine has a soul or not, the swami can assure you that the machine and all of its internal mechanisms invariably responds negatively to abuse and rough handling. Knowing how the machine works will hopefully give you reason to treat the machine in a manner that will substantially increase its lifespan.

So, let’s begin the journey of getting the power of the engine, through the clutch, to the gears and shifting mechanism that finally makes the drive wheel turn. Understand that the following is a grossly simplified version of the system. If you want to see all the parts that go into the Bajaj engine and transmission click here  to see an exploded view.

The engine is running, but we’re not moving. Most people at this point can say without equivocation that the scooter is NOT in gear. There is no connection between the engine and the rear wheel. It is vital in the scheme of things to be able to start the engine and not immediately have the vehicle take off. In fact, to be able to do this is so important, there is a safety switch that prevents you from starting the engine unless the gears are in neutral.

At some point, if you have any intentions of going someplace, we need to connect the power of the engine to the rear wheel, but we want to do this at a time of our own choosing and in a controlled manner. If we were to suddenly connect the turning engine to the non-turning rear wheel. There would be a sudden lurch, unpleasant noises, followed by the engine speed going to zero rpm, and sadly, we have abused, and possibly damaged, some mechanical components in the process.

The swami will now introduce you to the CLUTCH! In the Bajaj scooter the clutch is a stack of interlaced, alternating, circular plates about 6 inches diameter. One set of plates (all finely machined steel) are connected to the transmission gears and the other set (steel with a friction surface bonded to the steel) are driven by the engine. This alternating stack of plates is squeezed tightly together by strong springs.

Here’s a simple demonstration how the clutch works: interlace your fingers in front of you. Let's say your left-hand fingers are the engine clutch plates and your right-hand fingers are connected to the drive gears. Slowly slide your hands, while keeping your fingers interlace, together and apart. You can feel some slight friction between your finger as you do this. As you continue to do this, have someone slowly and gently begin to squeeze your interlaced fingers together. At some point you will no longer be able to slide your fingers, your clutch example is now engaged.

When you pull in the left-hand lever, you are pushing against the springs and releasing the substantial pressure that was tightly pushing the plates together.

So, let’s get ready to go. We are now at the moment of truth… clutch lever pulled all the way in, clutch plates disengaged, engine running and first gear engaged. (We’re a little ahead of ourselves with the gear engaged, but we need it for the next bit of instruction.)

Here comes the part that is the nemesis of all beginners, the single most difficult part of manual shifting, that seemingly simple act of making the smooth transition from standstill to moving. Note the use of the word smooth. Smooth is better… for you, the engine, the transmission, people in your path, and most important of all, your ego. Is there a secret trick to successfully making this smooth transition the first time and every time thereafter? Of course there is!!

The trick to starting smoothly is having clearly imbedded in your mind that the clutch has many positions between "engaged" and "disengaged". THE CLUTCH IS NOT AN ON/OFF SWITCH!!…. It’s more like a light dimmer.

The very important contribution that the clutch makes, is its ability to transfer power from the engine, through the transmission, to the drive wheel, in controllable increments through the process of controlled slippage. Remember your interlaced fingers? In between loose and "I can’t move my fingers" there were many degrees of resistance as a result of the varying clamping pressure applied to your fingers. With your left hand on the clutch lever, you will have control over hundreds, if not thousands, of variations in slippage. With this knowledge, and a little practice, you will be playing that clutch lever like a Stradivarius.

Wait! You’re not ready to go yet. Be it scooter, motorcycle, or tractor, if it has a clutch you need to learn its personality… especially if this is your first time using it. Every clutch type has different slip characteristics, and even between like vehicles, a clutch might behave differently. You will perform the following "getting to know you" exercise with your brakes firmly set, the transmission in gear and your engine speed never more than a fast idle.

The first thing you want to find out is:

When does this clutch begin to show signs of being able to transmit power from the engine to the transmission? Starting with the clutch lever pulled in as far as it will go, place the transmission into gear. Now, with your foot on the brake, very slowly, in tiny increments, begin to allow the clutch lever to move forward. You must be patient as you do this, you will find that there is considerable movement of the clutch lever before anything begins to happen. At some point you will begin to notice that the engine is beginning to slow down. It is at this point where most beginners make the mistake of suddenly releasing the clutch lever. In fact, it is here where the most care, and the most control, must be exercised. The clutch plates are now very close together, another very small bit of movement and the clutch will be fully engaged.

The next thing you must discover is:

How sensitive are the clutch plates to clutch lever movements? Due to the mechanical advantage of leverage, the control of that last tiny bit of movement at the clutch plates may translate into a full ¼ to ½ inch movement of the clutch lever… or it may only be 1/16 inch! You find this out by increasing the engine speed to a fast idle, and while still securely holding the brakes, continue the very slow release of the clutch. You will continue to slowly release the clutch lever until the engine stalls. Don’t worry, you’re not hurting anything. You have discovered where the clutch becomes fully engaged. You have now experienced the full range of clutch control. You may be surprised to find that, due to tolerance allowances built into the system, that the full range of clutch control falls into a small portion of the full travel of the clutch lever. There are substantial dead zones before the clutch shows signs of engagement and after it is fully engaged. Get to know where these active and dead zones are. As you gain experience controlling the clutch, you will easily find, and effectively use, the active zone without having to think about it.

We are now ready to bring the transmission gears into play. While the clutch is disengaged, a gear may be selected without having any effect on the engine. The Bajaj scooter has 4 gear ratios to select from. 1^st gear for rapidly accelerating from a standstill and 4^th gear for cruising, and two gears in-between for those speeds and needs you experience in-between.

In the following discussion the swami will show how we select a gear and engage the drive wheel. 

The swami wants you to imagine a very large gear (6ft diameter) floating in front of you. This gear rotates on an invisible shaft that is about waist high. Meshed with, and driving, the teeth on this very large gear is a small 6 inch diameter gear, this 6 inch diameter gear is powered by a mythical engine through a virtual clutch.

Imagine how many times this 6 inch gear will have to go around just to get one revolution out of the very large gear. This is our first gear. When the engine is running, and the clutch is engaged, our fantasy set of gears are rotating; exactly like they would be in the real gearbox. The small gear going around at engine speed and the large diameter gear going around at a reduced speed. For the sake of simplicity, these gears, clutch and engine are magically suspended in mid-air without the benefit of any supporting structure or bearings. 

Have you ever seen a trident? Sure you have, this is the 3 pronged pitchfork that the cartoon devil always carries around with him to insure sufficient torture to scoundrels placed in his care. We’re going to borrow this devilish tool to demonstrate how we engage the drive wheel to the transmission gears. We need to modify our 6 ft. diameter gear a bit. We are going to cut a slot through the center of our big wheel. A slot long enough and wide enough so we can pass our trident into and through the center of the gear.

OK here we go! Start the engine, crank that thing up so our big gear is turning at a good rate. Holding the trident horizontal, at waist level, 

and thrust the trident into the slot.

YIKES!! the handle of your trident is suddenly spinning at the same speed as the big gear.

That demonstration was probably a little hard on cartoon hands.  Instead of holding the trident in our hands, we’re going to attach a wheel to the trident and use the trident’s shaft as an axle, and using the same magic as before, now we don’t have to hold the trident shaft in our hands. Where we put it, it stays.

Let’s make this next demonstration less violent. After we start the engine, we will disengage the clutch and let the big gear stop turning. Now, push the trident/driveshaft forward to slide the trident into the slot. Changes are pretty good that the prongs do not exactly line up with the slot.

We have just discovered another frequently embarrassing moment for a beginning shifter, and the opportunity to pass on another secret to successful shifting.

The slot in the gear, like your number on a roulette wheel, rarely lines up in your favor. Many novices carefully pull in the clutch and then give some serious thought to shifting before actually taking the plunge. By that time, the gears have stopped turning, only a few randomly lucky ones will have the concurrent mechanical alignments that allow the gear to be easily engaged with the drive wheel. Some uninformed riders solve this problem by pushing the scooter back and forth until engagement takes place.

So, is there a trick to this? Of course!!

Pull in the clutch and just before the gears stop spinning, shift into gear. It’s all done in one smooth motion…pull-shift. The gears slow down and stop quickly because the gears are in an oil bath that drags them to a stop. Do it the swami’s way, it’s subtle, and when done smoothly, people will admire your cool nonchalance as you effortlessly put your scooter into gear, first time, every time. If you forget and wait too long, just quickly pop the clutch lever out and back in, that all it takes to get the gears spinning again.

OK, we’re engaged in first gear. We slowly let out the clutch lever as previously discussed, we begin to transfer the power of the engine to the drive wheel, once we have fully connected the engine to the drive train we then begin to increase the engine speed so that we might accelerate and increase speed. At some point, the engine is turning too fast for its health and we will need to shift to a different gear ratio to achieve more road speed.

A second set of gears that have been added, the ones with both gears the same size. When engaged, this set of gears is going to turn the drive wheel much faster.

If we push the trident on through the center of the first gear set, we can then engage the slot in the second set of gears. Before we do this we must pull in the clutch and reduce our engine speed, otherwise, you get the same mechanical violence you saw the first time we rammed the stationary trident into the rapidly spinning gear. Before we engage the second set of gears we must allow the engine speed to reduce. To do this, pull in the clutch and at the same time, reduce engine speed and shift. Remember our trident/drive wheel is now turning and if we do this engine speed reduction just right, when we engage the clutch, there will be a perfect relationship between the engine speed and gear selected. Unlike when we first got underway, we can release the clutch at a much faster rate. If you have matched the speed of the engine to the drive train exactly, that is, if the clutch plate stack on the engine side is going at exactly the same speed as the clutch plate stack on the gear side, then there is no need for slippage and the clutch can be used as a switch.

Shifting too fast or too slow will give you a little clunk and a lurch when you let out the clutch. When done properly, you will feel it, you will know it. That sense of accomplishment you feel is well deserved. With practice you will do this engagement speed matching without thinking. Keep practicing with the knowledge that you are adding years to the life of your clutch and transmission. So, as we shift up through the gears, we need to remember to reduce engine speed each time we move to a higher gear.

There is one more element to this gentle art that requires our attention: Down-Shifting.  The art of down-shifting has been generally ignored, most scooter riders get through their entire life without ever experiencing the rapture of a cleanly executed down-shift. Sadly, they satisfy themselves with clanking and lurching down through the gears until they reach the safety of neutral.

If you are truly a "I can’t stand to be shiftless" person, you will not rest until you have conquered the subtleties of down-shifting. As you master this slightly tricky activity, you will be well on your way to the black belt level of Artful Shifting and will appropriately deserve that glow of superiority that you will exude.

While the act of downshifting is almost exactly the opposite of upshifting, there are obviously sinister forces at work in the universe that conspire to make people believe that downshifting is 10 times more difficult than up-shifting. The swami is NOT talking about just getting back to neutral, but the gentle and artful skill of going from 4th to 3^rd to 2nd to neutral in one smooth effortless series of hand and wrist flicks that would appear to an observer as slight-of-hand. Why is this so important for you to learn? Besides being kind to the drive train, as you slow down and downshift into a lower gear, you are always in a position to rapidly accelerate and remove yourself from a possibly dangerous road situation. At any moment, at any speed, it’s important that you have the ability to immediately accelerate out of a tight situation. Down-shifting (and up-shifting) gives you the ability, as road speeds change, to keep the engine speed within a range that provides maximum power and acceleration when you need it. For any kind of racing that requires frequent gear changes, the swami guarantees that those who do not down-shift well are relegated to the back of the pack.

Let’s start with us cruising at 45 mph in 4^th gear. We see the traffic light up ahead turn yellow, we know we might have to stop so we begin to slow down, as our engine speed slows we get to the point where we should be in 3^rd gear. We pull in the clutch and at the same time quickly increase the engine speed. This is usually referred to as "blipping" the throttle. We give the throttle a quick flip of the wrist and since the clutch is disengaged the engine speed will accelerate very quickly. As we blip the throttle, and the engine speed increases, at just the right moment we down-shift. How do we know the right moment? Practice.

If the scooter lurches forward when you release the clutch lever, your engine speed is too high. If you feel the scooter suddenly slow down when you release the clutch lever , you have not increased the engine speed enough. If you didn’t increase the engine speed at all, you may find the back wheel skidding when you release the clutch. Many scooter riders that are accustomed to the old 2 stroke engines, get away with this shifting faux pas because the two stroke engine does not have the braking qualities from engine compression that a 4 stroke engine has. So after downshifting their 2 stroke scooter they let out the clutch and the engine easily speeds up to match the road speed. Many 2 stroke scooter riders have downshifted a long black streak on the pavement while making the transition to 4 stroke scooters. 2 stroke or not, you should learn to downshift properly.

From 3^rd to 2^nd and 2^nd to neutral is the same story. You will find the right times to make the downshifts through experience. As you practice your shifting exercises, you will more and more often make smooth shifts that feel like an automatic transmission and you will always find yourself in exactly the right gear. Maybe that light you were slowing down for just turned green and you, with your shifting skills, are exactly in the right gear to begin accelerating again, while the person who thought neutral would be the place to be, is now struggling to get into the right gear.

Sorry, no tricks here, just practice and more practice.

With practice you will improve, and I dare anyone who has achieved their black belt in shifting to write to me and say that they don’t get an incredible sense of accomplishment from skillfully meeting this challenge.

For those readers who live in the flatlands, the swami says thanks for visiting, enjoy your scooter, go practice your shifting. For those who must contend with hills, read on.

On the streets of San Francisco, many a rider, with a manual shift scooter, have met their match. Getting started from a dead stop on a hill can be a considerable challenge.

Number one! Always come to a stop leaning to the left. That is, left foot on the ground, right foot on the brake. Without this configuration you are doomed from the start. If you are desperately holding the front brake with your right hand to keep from rolling backwards down the hill, you are going to have a hard time regulating the throttle properly.

Getting a good start on a steep hill is going to require an extra measure of precise control of the clutch.

Before tackling that monster hill, try this exercise. Find a small, not so steep, hill with no traffic. Stop someplace on the hill. While firmly holding the brake with your right foot, while in 1^st gear, slowly let out the clutch until you hear the engine slowing down. Increase power and let the clutch out a little more, now, slowly release the brake to see if the scooter will begin to move forward. If it does not, either clamp the brake down or just add some more power and release the clutch just a tiny bit more.

The difficulty here are all the different pressures you are applying with foot and hands to get the desired results. It's like hammering nails and threading a needle at the same time... tough and delicate. It’s going to take practice.

Once you have achieved a slight forward motion, pull in the clutch just a tiny bit… just enough to stop forward motion but not so much that you need to apply the brake. With just the right amount of clutch lever movement and just the right amount of throttle you will be able to obtain an equilibrium… the engine is at a moderate speed, you are not holding the brakes and just a tiny release of the clutch will begin to move you forward and a tiny bit of pull on the clutch lever will cause you to very slowly move backwards.

Spend time finding this equilibrium point on hills of different steepness. Due to the rearward weight bias on a scooter, there are some very steep hills you just don’t want to challenge, particularly if you are carrying a passenger. A few scooter passengers have been left lying in the street, at the bottom of a San Francisco hill, due to less than perfect clutch work.

Yes, I know this exercise wears on the clutch. Reducing the life of the clutch to save skin is a perfectly good trade in the swami's book of important values.

So get away from your computer, get on your scooter and go out there and practice!  Make the swami proud of you!

____________________

 The swami wishes to thank Eric Balderston for the cartoons that helped to make this complicated subject more understandable.  A picture really is worth a thousand words.... and thanks to W.A. Mozart for getting the swami through a few tough hours when this project began to drag a bit.  Many and sincere thanks to the encouraging and demanding e-mail asking the swami to hurry up with the shifting article.

If you're completely new at this, or not so new, the swami wants to remind you that there is a lot more to safely riding a two wheeled vehicle than good shifting.  The swami strongly recommends the motorcycle riding courses that are offered around the country.  Go to  www.msf-usa.org for information about rider courses that will make your scooter riding a safer activity.