There are a few basic tweaks that are both cheap and easy and can give you some lost horsepower. Much of this stuff is pretty basic maintenance, and if your motorcycle is nearly new, or immaculately-maintained, then they might not make much difference. But, if you're like a few guys we know and ride a motorcycle that's a few years old and a little worn at the edges, there's every chance it has lost horsepower and fuel efficiency due to the lack of maintenance.
For just a few hundred Baht you can spend a relaxing weekend day in your garage with some friends and you'll end up with a smoother, cleaner running motorcycle that gets more power and more kilometers out of your fuel.
The first problem we see often is the chain and sprockets. Don't laugh, but we had chains which looked like they had never seen lubrication. In fact, after examining your own motorcycle check out some of your friends also – you are likely the one hurt the most if you ride behind him. A worn, dried out and badly-adjusted final drive chain will soak up a heap of engine power. Often lubricate the chain, and a regular, deep-clean with kerosene or chain cleaner will get all that lost engine power back.
Missing sprocket teeth, a kinked and rusted chain or one caked with filth are all extremely detrimental in transferring power from the engine to the rear wheel.
Regular engine oil change, shame on you if you don't do this regularly yourself. Old, tired engine oil can spa power from your engine as well as accelerate the wearing process. The friction-reducing additives in modern oil degrade over time, so dumping the gloopy black muck out and replace it with fresh, golden multigrade can gain you a couple of horses as well as make your engine last longer.
And not forget, buy the best you can buy – cheap oil is in the end much more expensive.
Swapping to a race grade oil can give even more power gains by reducing friction and pumping losses, but you'll need to change the engine oil more often. Failing to replace race grade oil on time is even worse than regular engine oil.