The first motorcycle I bought was a old Yamaha 175 cc that was basically a street and trail bike. It had knobby tires and was a 2 cycle. It needed some work including fixing a problem with the return spring on the shifter position system. The bolt that the springs rested against was broken off, and that was inside the engine transmission case. I took it apart and taped the case in that area to a much larger thread because the mount for the original was messed up. For the next part of the work I would have been much better off if I had a lathe or at least had access to one, but back then I did not. So I then took a bolt that matched the threads I had just installed, and mounted that bolt it in a big drill with it offset on purpose so the center of the shaft of the bolt was not aligned with the center of rotation of the big drill chuck. Then I held the drill while on and put the bolt against a grinding wheel to grind the diameter of the bolt down to the size the return springs needed to rest on, not messing up the threads of the bolt so the threads still matched the new threads in the case. I put a nut on the bolt to tighten when the bolt was in the proper position to provide the center return for the shift return springs.
Unfortunately, I could not get all the gears in place to put the case back together so I had to take the whole thing to the local motorcycle shop and pay them to put it back together. It worked, and I did not have to buy a new half of the case.
I also had to fix the ignition system of that bike. I got new points from the local Yamaha dealer, but the coil was way too weak, so I used an old can type auto-transformer coil from an old Chevy. Also the tail light was broken so I used the red plastic from an old Chevy for that. I got it to pass inspection and drove it on the road for one year. But my brother, and cousins and I often took it to some abandoned strip mines and took turns riding it. We did that all months of the year including winter. Sometimes we strung a bull rope down a huge mountain with some holding the rope at the top of the hill and would take turns trying to ride up the hill. If you did not make it up the hill you could grab the rope so you did not have to fall all the way back down the hill. That bike took many tumbles and many parts got broken. We had a blast and all of us learned to ride, and how to get off a bike if things were going wrong.
Years later I bought a new 1980 Honda 750 K 4 cylinder. It turned out knowing how to get off when things went bad was a good background to have. One hot July day I was coming home from work and coming up 18th street. The car in-front of me stopped for a light, and when it turned green we started to move. I gave it the gas but it had not rained for many days and there was a lot of oil built up on the road. There was water on the oil from the air-conditioning condensate from cars sitting at the light and if I had been on glare ice I would have had more traction. The back tire spun and the bike went sideways and was facing a huge brick wall. The back tire was still spinning even though I had got off the throttle and the back tire caught and launched the bike towards the brick wall. I figured if this bike is going into that wall, I am not going to be on it. So I rolled off of it onto the asphalt. I was then on my back sliding on the asphalt and the bike started to fall sideways towards me, and I kicked it just behind the engine as hard as I could and it fell the other way. I kicked that bike so hard that I thought I broke my foot. I could not walk on it for several days, but it was not broken. And I had a lot of road rash that had to heal up.
Anyhow, the moral to all of this is " it is a very good idea to start off with an off road motorcycle and learn to handle a motorcycle, and how to get off one if you have to, before you ever get a street bike." There are no cars to hit you when you ride off road. Get a couple of years experience riding off road, and then if you still want to ride on roads go for it.