Synthesis of 1-methylcyclopentene from cyclopentene
In Friedel–Crafts alkylation you form a strong electrophile to break the aromaticity of a benzene ring, resulting in a species that is also electrophilic, but not on the carbon atom. It is much more energetically favorable to reform the aromatic ring by losing a proton to $\ce{AlCl4-}$, evolving $\ce{HCl}$ gas.

The reaction of the electrophile with an alkene forms another carbon centered electrophile, however, which can rearrange and will go on to react with other alkenes or with $\ce{AlCl4-}$. There is also nothing to stop the reformed $\ce{AlCl3}$ from continuing to react with the newly formed chloroalkanes, so overall it would probably be a big mess. I found a resource here that discusses the reaction of $\ce{AlCl3}$ with alkenes:


  


For your reaction, though, I would propose something a little simpler and probably higher yielding like this: