The only time you need to use a clutch on a motorcycle is when shifting into First, You aren't going to do any more damage to the gears than if you used the clutch. Its designed to work that way.
Slowly and if you are good you can change gears without using the clutch. Takes a little practice and a good ear or feel for when the engie is running at the speed to change without the clutch.
Yes. They have a manual 5 speed transmission with reverse.
the kawasaki 125 has 5 speed
Clutch out of adjustment or worn/damaged clutch brake. Or you're just not hitting the gears right.
The clutch will slip in higher gears first. Cruise about 40 mph in 4th gear and step on it, if the rpm's go up more then the speed your clutch is going
Unless the speed of the gears are in sync, it's going to be a grinding shift.
A suicide clutch is a clutch on some old school choppers and motorcycles, where to disengage the clutch instead of using a hand control on the handle bars, you would pull a handle on the side of the motor to engage and disengage the clutch. So at any real good speed if you weren't paying attention you could commit suicide changing gears ( loose your balance and fall off, ouch owee "road rash")
The clutch hydraulics have a problem is the most likely issue Either clutch master cylinder or clutch slave cylinder
If it is an automatic transmission, the speed of the engine (in rpm) is what makes the gears change. Accelerate too much and it will fly up through the gearbox when it is not supposed to. If it is a manual transmission, the gears shouldn't change without the clutch being depressed and you manually changing gear; at most, it will simply disengage and cease turning the wheels.
If the revs decrease as the speed decreases (in 3rd & uphill) then its not slipping, you don't need a new clutch, but if you are in any gear and the revs are increasing while the speed is decreasing, then the clutch is slipping.
For first gear, Hold the clutch, press the gear down, accelerate slowly and leave the clutch gradually... For the rest of the gears, hold clutch, press the gear down accelerate a little more than the current moving speed and leave the clutch a little faster than before...
depends on the motorcycle, i know the CVT transmissions can have different final drive gears installed for more top end but the acceleration from a stop will be less.