I must agree with Inquisitor Ralei. Jetbikes are a thing long lost to the Heresy. I think the fluff for Sammael even states that he rides the last remaining Imperial Jetbike.
That said, there is one way you could do it: make a Pre-heresey army! However, seeing as this is your own chapter, that wouldn't work. You could model them, but it simply (unfortunately) will not work fluff-wise.
You could say that they found a long lost warehouse/cache of techno-arcana, but expect to be hassled, and hunted by the Mechanicum.
__________________ Lord of Fluff and Blood Angels Herald of Nurgle "I wield my power with the Emperor's Authority. Those who would say that I am 'radical' merely have minds too small and impotent to realize all the weapons at their disposal. Do not question my methods on account of these so-called 'Puritans'." -Inquisitor Mathias Rosenadel |