Will 1986 KX500 power valves fit and work in a 1987 KX500? I've read different things from different sites. I was told that 87 and 88 were interchangeable. Then I read here on an old thread that 86 will work for 87. Are they all different for each year? This not a thread jacking, I'm asking for Bigchuck as he does not have much computer access.