downshifting

[alloo66]

I'm new to Shifting scooters. Are you supposed to downshift? What about riding down hills? I own a Stella 2t. Just curious. Thank you.

[magnato1]

I have a 4T, I downshift. As with any other manual vehicle, downshifting needs to be done properly. I'm no expert on the Stella though.

[Silver Streak]

It doesn't really make any difference what kind of manual-shift vehicle you are driving or riding... downshifting is necessary any time your road speed drops to a point where you are below the adequate torque range of the engine and will need to speed up again or when you are climbing a hill too steep to allow you to maintain speed in whatever gear you are in. It also may be desirable to assist the brakes on a steep descent.

For example, if you are in 4th gear doing 40 mph and coming up to a very sharp turn that requires slowing down a lot, you may want to shift down two gears to 2nd in order to be able to accelerate adequately away from the turn.

Downshifting smoothly requires learning a technique called "rev-matching." At any given road speed, the engine will be turning over at different revolutions per minute in each gear (higher rpms in the lower gears and vice versa). As a practical matter, what this means is that when you downshift from -- say -- 3rd to 2nd, shifting into 2nd and releasing the clutch without doing anything else will produce a substantial lurch because you are forcing the engine to instantly increase its rpms. This lurch is not only hard on the transmission, it is uncomfortable to you and any passenger, and it labels you instantly to bystanders as someone who does not know how to use a manual transmission properly.

To downshift smoothly and avoid the lurch, you need to rev the engine a bit by "blipping" the throttle at the instant you have pulled in the clutch and taken the scooter out of the higher gear, and you must still be maintaining those higher rpms when the gearbox goes into the lower gear and you release the clutch.

This takes practice to get both the timing and the appropriate amount of throttle correct. After a while, the whole action will be committed to muscle memory, and you won't have to consciously think about it at all.

[alloo66]

I know for every other vehicle downshifting is normal. What about two strokes since they're oil injected?

[BuddyRaton]

I know for every other vehicle downshifting is normal. What about two strokes since they're oil injected?

Not all 2Ts are injected. If no injectors you have to be very careful...especially on the downhills. For my CBR premix scooter I used the headlight switch as a cut off switch. Going downhill I would kill the motor but keep the throttle open about halfway to get fuel and oil. Near the bottom I would just flip the switch back to on and hit it!

[magnato1]

If it's premix, why do you have to turn the scooter off?

[az_slynch]

On a premix bike, the oil enters the carb the same way the fuel does. It comes in through the brass tube that pokes out of the venturi wall, upstream of the throttle slide. Closing the throttle cuts off the oil.

He leaves the throttle open halfway, but kills the ignition in order to keep the crank, bearings and cylinder lubed without the result associated with going downhill with a half-open throttle: acceleration.

I have a pre-mix bike, but I tend to blip the throttle often while going downhill. Even though the automatic oiler is feeding regardless of slide position, it doesn't hurt to hit the piston with a cooling fuel charge occasionally to keep thermal expansion under control.

[magnato1]

I get it. I'd never really thought about that. Makes sense, thanks for the clarification.

[BuddyRaton]

And after climbing at about 6-7K rpm in third it really helped cool the motor down!