When I get an old beater CT90 that I decide I want to get back to where it is fully operational, I generally follow the process outlined below. The abbreviated version: 1. Clean it 2. Get it standing on the center stand 3. Drain the oil and flush once or twice as required 3. Get it rolling and work on the brakes while the wheels are off the bike 4. Work the wire bundles and electrical system. Get a battery and get everything working 5. Clean/rebuild carb, clean gas tank, get new fuel lines and a filter for each line. 6. Work the top end of the motor 7. Do any work to the lower half/transmission 8. Put everything back together and adjust valves, point gap, then timing. 9. Put in a new plug 10. Get it started and enjoy your rebuilt CT90!