Serial numbers are usually on the left, lower frame section, below the shifter and flywheel cover..... Looks rusty on the part in the left side motor picture,.... the numbers are probably still there though.

 

The numbers on my 89 350 Moto 4 was on the frame under the foot peg.

 

are they stamped into the frame or is it a tag? I do not see anything under the foot pegs.

 

look at my pics you can see the 84 alt125 i had the very first atv made was very very similar looking just 2 wheels up front, far as i know it was 83 when suzuki came out with that, there should be a number on that moto4 on the frame around the footpegs, there pretty small numbers and might not even be there anymore lol, from wear and tear, i know my warriors are barely visible.

 

On the Frame tube

 

Mine was stamp in the frame ,but I could only make out 3 number because they take a beating from rocks and things.

 

I also need to fix or replace the Switch Assembly. The starter button is stuck in and I can not get it out. I found a used one off a 89 YFM350. It looks just like mine. Do you think it will work?

 

If they look the same and have the same amount of wire coming out of them,then there probably the same.

 

On the right side of the motor is has a nut and above it, it says increase and decrease. what is that for?
how do you shift into reverse?

 

I think that adjust the wet clutch plates pressure,if the clutch begins to wear and slip,I never needed to touch it in the 3000 miles I used it. If I remember right you either put the ATV in neutral or 1st gear and pull the leaver by the foot rest.