I'm willing to bet the brand new Helix are stiffer than your old ones
....I might as well have been trying to fit steel pipe.
The stuff was so stiff, it found it's way into the front sprocket of my 250 as it was trying to go back into it's rolled form as it came packaged....and it wiped out my sprocket seal, so tranny oil was dumping out.
I drained the oil twice through a paint strainer and found a bunch of chewed up vent hose.
So at that point I ordered the expensive OEM hoses...but have yet to swap em out yet.