Your single bulb has filaments, one for the low beam and one for the excessive beam. In case you take a look at the again of the headlight bulb, there is 3 prongs. One is for the low beam, one is for the hi beam, and the final is the shared floor. The low beam and hi beam want to be became on and off independently, so you want relays. I've bike with 35 watt hs1 bulb and i need to improve brightness of headlight so i determined to put h4 60/65 watt xenon bulb. An expert on this discussion board counseled me to apply relays as the brand new bulb calls for greater power. I did some google to understand relays and the way to wire new headlight with relays, however the confusion is that the hyperlinks and motion pictures for relay wiring that i found online changed into for vehicles and car has two head lighting so they have used spdt(bosch) relay for that however for my motorbike i want best one bulb so i bet single 30 amp spdt relay could be enough however i'm careworn what have to be the circuit diagram for single spdt relay to control headlight hi-lo beam. I recognise rather than making setup from scratch by myself many of you will recommend me to head for eastern beaver h4 package however the problem is that i'm in india and i dont have any paypal account to pay for kit or even now not certain whether or not this package could be within your means for me or no longer thats why i determined to make this setup by myself.