I bought a mudbuddy frame used with merc trim, owner said around 25 hours use. So now I am looking for a big block motor. While looking on ebay I saw this: http://www.ebay.com/itm/35hp-Briggs-Str ... 53ef2c2464 . I run long distances wide open(aroun 4800rpm) in the summer and have had worries of getting hot. I don't know if the usual mods will work either. Last motor had 60hrs, heads, mikuni, cam, ported intake, roller rockers, push rods, pistons blah blah. I noticed one time during a long run the engine started to drag a little, immediately slowed down and it got better. didn't run it really hard rest of the day. Few weeks later I pulled the heads and the cylinders were lightly scored. Not enought to hang a nail on so I put it back togehter and always had that worry in my head when riding. Could the scoring be from heat either in jugs or from getting oil too hot? Thanks in advance

Why not just add a larger oil cooler in front of flywheel fan?