How do I adjust the timingfor a Yamaha breeze 125?

The H isn't the letter H, but a range where the spark should be firing. T is the letter T, and stands for timing. The I should be right nevt to the T, and this is your timing mark. Confirm this by putting something in the spark plug hole as you SLOWLY turn the motor by hand. You can feel the piston come to TDC. TDC should coincide with the timing mark on the rotor. Once that is set, you can make sure your cam is where it should be and you're all set!