You must make sure before changing to a higher wattage headlamp bulb such as a 60/65W H4 that all the wiring and switches for the headlamp are able to carry the additional current that a higher wattage bulb will draw.
Your current headlamp is listed as a 35/35W, so the 60/65W will draw nearly twice as much current.
Without knowing what type of wiring and switches are provided on your bike, I would suggest getting a headlight relay kit before changing bulbs to the H4. The relay kit provides all new wiring to go straight from the motorcycle's battery to the headlight bulb, and relays, which are like remote controlled switches for the high-current headlight bulbs. Your existing wiring and handlebar hi-beam switch will now control the relays, which will turn on the low and high beam.
If you get such a relay kit, you can definitely safely run the H4 bulb on your bike. The relay wiring kit provides a "big pipe" for the electricity to flow through to your headlights, ensuring that you get full voltage and therefore full brightness out of your headlight bulb.
In actual fact, a headlight relay kit is a good upgrade for nearly any motorcycle. Cars almost always come with relays for headlights, motorcycles almost never do. Therefore you have a big potential for increased brightness even with the factory bulbs.
Well-reputed relay kits are available from eastern beaver, and the owner is a very helpful guy who can walk you through the process.
NOTE: I am in no way affiliated with Eastern Beaver. Similar products may be available elsewhere.
Another option would be to leave your headlights alone and add "accessory lights" such as driving lights or fog lights. There are high-powered LED lights available that have very low power requirements, which make them great for smaller motorcycles.