<VV> NO Corvair - Lawnmower questions

[GYoungwolf@aol.com]

Since there is no lawnmower website, I thought I might apologize in advance 
and ask someone who is experienced in B&S engines for some insight. I have a 19 
HP twin I/C engine with electric starter (51" deck) which will barely turn 
over and will not start when it is hot. (The battery cables also get hot). It's 
fine cold, however. I have noticed a slight loss of power, so I guess the 
heads might need cleaning, but everything else seems to work properly (battery 
charges, no smoking, etc.). I swapped the starter thinking it might be the 
problem (and it could still be, since the replacement was also used). Thanks for any 
advise. (I am also considering replacing it with a larger 54" mower with a 25 
HP Kohler engine, so any insight as to it's reliability compared to a B&S 
would be appreciated.)
Grant