Got a Chinese pit bike, mini chopper, or pocket bike?

[low_budget]

While this has nothing to do with console hacking, I thought it might be useful to anyone that has a pit bike / mini chopper / pocket bike with a 4 stroke Chinese clone Honda XR50 style engine. I recently came across a cheap mini chopper that needed a lot of work. I looked everywhere for a decent wiring diagram and couldn't find one. So, I made one using MS paint!

The color codes are correct for engines made by Lifan, Zongshen, Loncin, etc.
Only the CDI, ignition coil, and kill switch are needed for the engine to run.
I am checking on powering a headlight directly from the regulator without a battery, but the battery may be needed to help regulate the voltage.

I also have some tips if anybody is fixing one of these:

These engines are very reliable. Most of the time the problem is with the fuel system (carburetor and/or fuel supply.)

Fixing and tuning the carburetor:
When I got mine some moron "sealed" a float bowl leak with caulk. Caulk turns to a gummy gel when it comes into contact with petroleum products. New carburetors for these are very cheap, so rather than figure out everything the last guy screwed up, I bought a new one.
Make sure the main jet is the right size for the engine. If in doubt, use the main jet from the old carburetor. The main jet is in the carburetor float bowl and has a number etched onto it indicating the size. There is also a low speed fuel mixture screw on the outside of the carburetor. Adjust it by turning clockwise in until you feel some resistance, then back it out 1-1/2 turns. This is a good starting point for later fine tuning.

Cleaning the rusty gas tank:
The gas tank was very rusty, so bad only thick, dirty gas would come out. I cleaned the tank by putting acetone and a small length of chain in it and shook it to loosen the rust. I flushed the tank several times until it was acceptable. A telescoping magnet is also useful for removing rust. Always use a fuel filter if the tank has rust inside. I also had to clean out the petcock, but it was still usable.

Adjusting the clutch:
The mini chopper I got had an automatic clutch. The adjustment must be just right on the engine will not engage/disengage properly. To adjust the clutch, remove the right hand cover (2 screws) and underneath is a slotted screw secured with a locknut. Loosen the locknut, and turn the slotted screw counter clockwise until it is loose. Turn the slotted screw in until you feel resistance, then back it out 1/8 to 1/4 turn and tighten the locknut.

Fixing the brakes:
The front hydraulic brake also needed work. It had a leak at the sight glass in the master cylinder. It too was sealed with caulk. I busted out the whole sight glass (or plastic in this case), removed the brake fluid, and cleaned the entire area with thinner. Then I sealed it up with good ol' JB weld. After it cured I refilled the reservoir with fresh brake fluid and bled the brakes using a vacuum pump. You can still do it without a vacuum pump but it is a pain.

These engines are great for many home projects. If you buy one, make sure it has a manual clutch. The auto clutches are horrible.