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I searched around a lot about this, and found a lot of conflicting and incorrect information about using a H4 bulb in the grom.
So the stock headlight bulb is a type HS1....this is NOT the same as a H1. It's fairly common in small-displacement powersports, but otherwise rarely used so you're not likely to find it in stock outside of bike dealerships. It's a 35/35w bulb, meaning both low and high beam are 35 watt power. The HS1 bulb is almost identical to the much more common type H4 bulb in fitment. The wiring connector is identical. The plate is the only slight difference. On both the HS1 and H4 there are three indexed tabs on the base so the bulb only fits in one way. These are identical. The difference is two tiny front-facing indexing tabs at the 180* position of the plate, or the bottom side. On the HS1 they are spread slightly farther apart than on an H4, enough that a H4 will NOT fit properly just dropping it in to the stock grom headlight, the base won't sit flush since the tabs won't line up with the slots in the headlight.
The solution is easy, take a pair of needle nose pliers and fold these little tabs flat again on the H4, then install as normal. I used a basic Philips xtravision h4 55/60w bulb from walmart that cost like $8. Aside from taking 10 seconds to fold the two tiny tabs down, it was a direct replacement. The stock connector fits right on. Light output is dramatically improved and the headlight no longer sucks. I'm sure some of the HID or LED options are brighter still, but considering the speeds this bike is capable of, it's plenty for me.
Now the question people kept bringing up but nobody had an answer to was: will the higher wattage overload the wiring or drain the battery? Answer: no, it won't. With this bulb on high beam at 60w and the engine at warm idle, I still had 13.2v across the battery, above the standing voltage of 12.6, so the battery was still charging. At 3000rpm on up, it was up to 14.4v, which is the ideal regulated voltage. This was with the stock front running lights. After 30 minutes on, none of the wiring was warm and nothing was excessively hot, so it's not going to melt your headlight or run your battery flat or anything.
This was on a US spec headlight, so I can't confirm no adverse effects with the projector style headlight, since on those the bulb sits in a much smaller fisheye enclosure and could be more subject to heat buildup.
So the stock headlight bulb is a type HS1....this is NOT the same as a H1. It's fairly common in small-displacement powersports, but otherwise rarely used so you're not likely to find it in stock outside of bike dealerships. It's a 35/35w bulb, meaning both low and high beam are 35 watt power. The HS1 bulb is almost identical to the much more common type H4 bulb in fitment. The wiring connector is identical. The plate is the only slight difference. On both the HS1 and H4 there are three indexed tabs on the base so the bulb only fits in one way. These are identical. The difference is two tiny front-facing indexing tabs at the 180* position of the plate, or the bottom side. On the HS1 they are spread slightly farther apart than on an H4, enough that a H4 will NOT fit properly just dropping it in to the stock grom headlight, the base won't sit flush since the tabs won't line up with the slots in the headlight.
The solution is easy, take a pair of needle nose pliers and fold these little tabs flat again on the H4, then install as normal. I used a basic Philips xtravision h4 55/60w bulb from walmart that cost like $8. Aside from taking 10 seconds to fold the two tiny tabs down, it was a direct replacement. The stock connector fits right on. Light output is dramatically improved and the headlight no longer sucks. I'm sure some of the HID or LED options are brighter still, but considering the speeds this bike is capable of, it's plenty for me.
Now the question people kept bringing up but nobody had an answer to was: will the higher wattage overload the wiring or drain the battery? Answer: no, it won't. With this bulb on high beam at 60w and the engine at warm idle, I still had 13.2v across the battery, above the standing voltage of 12.6, so the battery was still charging. At 3000rpm on up, it was up to 14.4v, which is the ideal regulated voltage. This was with the stock front running lights. After 30 minutes on, none of the wiring was warm and nothing was excessively hot, so it's not going to melt your headlight or run your battery flat or anything.
This was on a US spec headlight, so I can't confirm no adverse effects with the projector style headlight, since on those the bulb sits in a much smaller fisheye enclosure and could be more subject to heat buildup.
