Keep in mind, the newest Seca II was sold in 1998. That's 15 years old. Most of us are on '92 and '93 models which are more than 20 years old. On top of this, most Seca II's are stored or neglected and purchased in unknown or poorly maintained condition. When performing maintenance on a new-to-you Seca II, keep its reliability for the upcoming riding season in mind and assume that it has had no maintenance.
A thorough maintenance program for your Seca II should include:
- 1. Change the engine oil and filter
2. Check valve clearances and adjust to spec
3. Set the carburetor float heights
4. If not already done, install a #20 pilot jet and drill out the pilot screws when the carbs are removed
5. Replace the intake manifold rubber seals
6. Replace the vacuum and fuel hoses
7. Replace the fuel filter
8. Syncronize the carburetors and set the pilot screws (infrared or O2 sensor method)
9. Clean and rebuild the fuel petcock
10. Clean the fuel tank and derust if needed
11. Clean out the airbox and blow out the air filter. If the filter is dirty, replace it.
12. Install new spark plugs and check the resistence on the resistor caps
13. Verify condition of the battery and replace it if it's at all questionable
14. Bleed the brakes with fresh DOT4 fluid and inspect the pads for thickness
15. Change the fork oil and replace the fork seals
16. Clean the chain thoroughly, lubricate it and adjust it's slack. Replace the chain and sprockets if they are questionable
17. Unless they were made within the last 5 years, replace the tires as a set.
18. Check wheel bearings condition and replace if needed.
19. Lubricate the throttle and clutch cables and adjust their freeplay.
20. If they're still original, replace the headlamp and tail/brake lamp.
21. Lubricate headset bearings and torque to spec. If bearings are worn or have excessive play, replace as needed.