Kanye West -- Ripped Off Samples for 'Bound 2' ... Claims Ex-Child Star

Kanye West may dry hump Kim Kardashian in the "Bound 2" video, but a former child star says he's the one getting screwed in the song ... claiming Yeezus stole a sample from his old track and never paid up.

The guy behind the lawsuit is Ricky Spicer -- an ex-member of the '70s soul group, "Ponderosa Twins Plus One" ... which recorded a song called "Bound" back in 1970.

Spicer, who was 12 years old when he laid down the track, says he recently heard Kanye's new hit on the radio and IMMEDIATELY recognized his old work.

Problem is ... Spicer says he never granted Kanye (or anyone affiliated with Kanye) permission to use his voice ... so on Monday, he filed a lawsuit in Manhattan.

Ricky is suing the rapper's labels for allegedly stealing his vocals ... and is demanding West stop using the song and pay him an unspecified amount of money.

Just listen to the song ... the Ponderosa Twins' ditty is clearly the main sample on "Bound 2" -- and Kanye's title suggests his version is a sequel to the original.

But this ain't Kanye's first rodeo when it comes to sampling music (see: Stronger, Gold Digger, Diamonds from Sierra Leone, etc.) ... and it's unlikely he would just jack the tune without trying to obtain the rights.