pipe installation help

Hello Everyone,

I am in the process of installing a Pro Circuit pipe on my 2001 RM250. It did not come a o-ring and the original one appears worn. I went to the dealer and got a OEM o-ring. It fits on the pipe but I am having trouble sliding it into the motor. I applied oil to the o-ring, but it appears to be two thick. Is there a trick to getting the pipe in? Any help would be greatly appreciated.

Thanks,
Gene