Advertisers work hard at stopping people from making choices in their best interests. Don't give them any more help they don't need it.
Put the money that's wasted in ads into design. That's what Tesla has done and it's worked pretty good so far. That's what the OP wants. What about motorcycle brand (image) X makes you want to spend more money on it? That's why we have a $30k Livewire guys. Image.
Be better than gas, at everything. Then tell the world. No image no excuses just be better. And they will be.
Of course a strong brand is usually more expensive than an almost unknown one, but that's not only due to advertising costs. Anyway, you can't think that big companies such as honda, ducati or harely will just stop branding their products, otherwise the market will be undifferentiated and they won't make money.
Anyway, ours is only an academic research, we don't have interest in selling. So maybe we will find out that brands are not important at all for electric motorcycles, who knows...