Re: GS750 build
I have a 78 gs750..INCREDIBLY reliable machine, good 'ol points and kickstarter.
That baby fires up Every time, ride it across country, no problem.
You need to ensure All of the maintenance is done, before worrying about forks, lol.
-Fuel : clean gas tank, petcock.
-Carbs: should be Mikuni VM29's, break them down, dip them well. Order new gaskets and O-rings. Ensure fuel and air screws are set within the ballpark of specs, then Bench Sync them. Then fire it up and tune them via the "highest idle method"(google-hint hint). Then synchronize them with a sync gauge. Also, ensure floats are set to spec(25-27mm).
-Air: Use the FACTORY airbox, you need this as a benchmark to get the bike running properly. If you use Pods, you're in for a world of problems and a blown engine.(unless you bump up the Mains, needle clip, floats, etc....)
-Engine: Check the VALVES, if they fall below 0.03mm's, you can burn valves. The spec is 0.03-0.08, although many people run excess of 0.10 gaps....the looser the better, within reason.
-Spark: Spark plugs have a nice Blue spark? Also check the plug wires and caps..they are known to corrode on older bikes.
-Electronics: connections clean, no loose wires? 12.6v's at battery and 13.5 with bike running at Idle? If you rev to 5k, you should get around 14+. (to ensure charging system is working)
All of this, is common sense maintenance...but just thought I'd mention it anyways.
Thanks and good luck!