1995 Suzuki Intruder 1400 clutch feels spongy

The problem is most likly not the clutch master cylinder. I have had this problem .The fix is replace the hydrolic line from the master to the slave cylinder.the original from the factory is a mix of rubber and steel .what happens is the rubber swells and will make for a spongey clutch or the steel will corrode under the rubber sleeve causeing a loss in pressure and fluid you will not see the leaks perhaps untill you remove the old line .The neww replacement line from suzuki is stainless steel and not a rubber hose and works really well .It is not an easy thing to install the line if not mechanicly inclined do not atemp to do this repair by yourself..before you take time to rebuild the master do this first and then eliminate the master and the slave ..I hope this will save a lot of time and give you more time to safely ride your bike .It took me quite a while to figure this out it definately works.

I had the same issue. I used dot 4 break fluid, tilted the bike on end so the clutch reservoir near the handle was level. Poured in the fluid till it was full. leaving the cap off. Opened the bleed valve located behind the cover plate just to the left of the drive shaft on the left side of the bike. take the rubber cap off and use a 10mm nut to barely open the bleeder. Pump the clutch handle until it starts to pull in the new fuild and spit it out. Next top off the reservoir near the clutch handle. Seal the lid tight. Put the bike back on it's kick stand. Next do this about 10 times. 1. open bleers. pump clutch. close bleeder, release cluch. open bleeder, pump clutch in, close bleeder, release clutch, open bleeder, pump clutch in, close bleeder, release clutch.

The clutch will get very tight and feel awesome next time you ride.

You will have to bleed the clutch hydraulics.
If it diesn't get any better after the bleeding process, thn you will have to overhaul the clutch master cylinder, best would be to overhaul both Master and the slave cylinder.
Hope this helps!