New kernel installation

I have few boxes with Linux RedHat 6.0, in a range from 486 to Pentium II. The problem is that any new kernel that I compile, I can install afterwards only on the Pentium II; from 486 I get “The kernel image is too big”, even if it is 2/3 of the original 2.2.5-15 one. To test the install, I’ve added the same image to the PII system, and it was OK. (The 486 config: 16 MB RAM, 540 MB HDD, no X system, 66MHz clock) (of course, the kernel was compiled on the PII but with the 486 characteristics). -v option for lilo was clueless. Thank you for any ideea.