Basically you'll have to hold on to it for about 150 years. Japanese bikes (good as they are) are not "investment quality" unless it is rare. For example a Honda 250 cc six cylinder race bike sells for about $1,000,000.00 because they only built about 6 of them (although a Brit is currently making knock-offs for $500,000.00 a pop). The Yamaha GT1000A will be a classic very quickly (few made and fewer sold). A 1960's Honda CB77 305 will fetch upwards of $2000.00 in pristine condition. To get a CB77 in pristine condition takes about $10,000 in labor and cash. If you want to hold onto the bike because you enjoy it, that's a good reason not to sell. If you're thinking it needs to go under glass to hold its value, you need to wake up and smell the coffee.