ripped intake rubbers

Hi, I recently installed a set of mikuni rs34s on my 77 z1000 and used new intake rubbers (Part no 16065-1135)after about 2 weeks it developed a vacuum leak and I found 2 ripped rubbers. which I replaced thinking they may have been faulty. 3 weeks later it has happened again! I had 29s on for 15 years before that and they were on the original rubbers and never a problem. Any ideas?
Thanks in advance, Jason

1/4" thick rubber ripped? That is very unusual to say the least. You can really see a rip? I'm no help but curious as well.