Cleaning VW heat riser tubes

Clutch Cable info: www.amazon.com...
If you were wondering:
Q) Why do we need to clean these heat riser tubes? It's nasty!
A) Due to venturi-effect in carburetor the fuel freezes while being dumped into intake manifold. In order to avoid engine from fuel starvation, we need constant heat - it even freezes when its around 80 degrees F!! (similar to Cessna or single engine planes)
Q) Why not just a new one? They aint that pricey!
A) These original ones fit very well. The news ones will need mod/twisting to fit properly.