According to the next update u'll have to be lvl 8 in basic craft to slot bikes.
How to get to that fast.
First u have to save 1b (easy after the update)
Second buy return stone formula cards for all lvls (at least to lvl 5)
Third destroy all slotted items and stack upgrade and force core pieces as much as possible.
Fourth begin to craft return stones (fastest and easiest way to go rocket fast)
(DO NOT craft mp potions as some says it's the fastest way to get lvl)
Fifth You have to get formula cards for eppy of proof +4 and +5 from the 1b u saved.
To get profit from basic craft get formula cards for fury potions lvl1,2 and 3 in addition to formula cards for sword master potions and magic master potions (lvl 7 in basic craft).
Don't try to caft SEHs, YOU'LL FAIL.
To make more profit get like 1000 runia station cards (Or more lol) go there proceed to the second boss kill him if dropped formula card of SEM get it if not give up the dung and go back n so on until u get it (this is so funny, y i'm laughing at this idea. brb ....loling)