As a rule, I tend to avoid modified motorcycle and scooters. Generally, this is because they are changed to one particular person’s idea of what they should be, do or look like. Another reason is because so many are bodge jobs and few people are capable of significantly improving a manufacturer’s product.
Yet another is that they increase your parts hassles, unless you know exactly what has been done.
Changing things like rear shocks and other service items is one thing. But say you buy a Suzuki Bandit 1200 (which is not officially available in Thailand) that’s had a Suzuki GSX-R1000 front end fitted after a serious accident. What model? K5? K7? And what are the brakes from??? And that master cylinder doesn’t match anything you’ve seen from Suzuki. And after some serious searching and asking around you find that the calipers are from a Yamaha…
The real issue I have, if I’m trying to buy and sell something is that people think throwing thousands at a motorcycle magically increases its value by whatever they’ve spent. I have a stock answer for that: you can spend hundred-thousand Baht on a motorcycle to buy aftermarket parts, but that doesn’t mean it’s worth 20,000 Baht to anyone.
People expect a stock product to perform to a certain standard. If you have spent a lot of money to improve that standard by, say, 10% - a 10% increase in top speed, or 10% improvement in economy, handling etc then for the average buyer, that might justify a price premium of 10%.
But it can cost a hell of a lot to achieve a 10% improvement in anything. If you’re selling a motorcycle that’s been modified, try and put it back to stock and sell the various bits and parts separately to get the best return of your invested money.