How to replace bendixs on starter

For the quad, I can only speak from automotive experience but does the starter have a smaller cylinder mounted directly on it? If so, this is the magnetic solenoid that engages a Bendix gear drive on the starter shaft into the engine flywheel gear to crank it. The actual switch that turns on the starter motor itself is in the back end of this solenoid. If the motor turns, the solenoid is working. If it doesn't have this solenoid, it will have a shallow screw drive cut directly in the motor shaft with a Bendix drive gear on it. When you hit the starter, the shaft turns quickly and basically "unscrews" the Bendix drive to the end of the motor shaft and engages it with the flywheel gear, again, cranking the engine. The weak link in both of these systems is the Bendix drive itself. It has a built in ratchet based on ball bearings so that if the shaft happens to stick in the engaged position after the engine starts, it will only spin the Bendix drive itself and not the starter motor avoiding damage to it. These ball bearings will eventually break up allowing the Bendix to free wheel in both directions instead of catching in one direction to crank the engine and slipping in the other direction to protect the motor. I hope this helps.

Power from switch goes to the starter solenoid only. The solenoid actuates the starter bendix, the bendix then engages the flywheel and cranks the engine. If you only hear clicking, it's a weak connection of the cable to starter from battery. Possibly the cable is too light if it gets too hot when trying to crank. If all it does is the clicking, the solenoid is bad or battery too weak. It has to at least click, you said it works off the car.

if your saying your starter stays engaged after starting engine till you cycle thru the gears , your starter needs serviced , most likely a worn bendix pivot bushing

two options 4 repair
1= replace starter
2= remove starter and have it professionally rebuilt then reinstall it

Not likely. More likely is that the starter, or the starter solenoid is bad.
This is the way it works. Turn key, car checks to see if all safety items are OK (in neutral or park, brake pedal depressed, etc), if OK then sends signal to starter solenoid to engage(it's basically just a magnetic switch), which allows the full power of the battery to turn the starter and engage the bendix, which engages the flywheel and turns the motor. If any of those things are bad, the car don't start. If it's the starter, the bendix will make a metallic click or thunk. If it's the bendix, the starter turns, but not he motor. If it's a fault in the electrical system, then no starter, and no bendix. If the battery is weak, the bendix may or may not click.
To repair;
1; starter can be rebuilt, including the bendix. moderately expensive if done by shop. Inexpensive if you can do it yourself. Warning - it's a PITA to get it out!
2; selenoid can be replaced. Usually inexpensive, except for shop charges. It sets on top of the starter.
3; If electrical; this can get expensive as it is labor intensive to track down the fault, even if the part is usually inexpensive.

check battery power and its charging otherwise selfstater problem

Check timing belt first , check starter also .

try a little light oil on the starter shaft

this could be a few problems that cause this,

1. your battery could be weak and not have enough juice to engage the starter solenoid

2. the bendix could be messed up

3. this is probaly the most common problem, the starter solenoid went out

the best course of action would be to have your battery load tested, and if its fine, replace the starter

4000 kW is a very big generator. I asume that your is 4000W = 4 kW.
If - with electrical start it should be MicroQuiet 4000.
Never mind by all types of electricaly started engines this will mean:

If by "not engage" you mean that solenoid only clicks, but neither the starter motor is turning, nor the bendix wheel is engaged to wlywheel. This may mean that battery voltage is low, in order to engage the bendix and make its power contact, or the bendix is mechanicaly blocked.
If by "not engage" you mean that solenoid clicks, the starter motor is not turning, but the bendix wheel is engaged to wlywheel. This may mean that the bendix relay power contacts are bad or starter motor collector or brushes are bad.
If by "not engage" you mean that solenoid clicks, the starter motor is turning with a scratching sound, the bendix wheel is partially or not engaged to wlywheel. This may mean that the bendix throw out lever is bent or broken, or the wheels on bendix and flywheel are worn out..

Hello there:
The spinning that you are hearing is the bendix spinning there is a
engagement spring that forces the bendix to engage on the flywheel
If this spring is weak or broke the bendix cant engage furthermore if the teeth on the bendix are broke or chipped or the teeth on the fly wheel are chipped or broke -this will not allow the bendix to engage or start to turn the motor ok so i would have these things checked out ok?
I hope that this is very helpful for you best regards
michael