Re: 85hp 1987 Force - Water Pump?
The thermostat is located at the top of the head inside the square box held by four screws. If the engine is cooling, why bother changing the thermostat--if it aint broke, don't fix it.
4500 is at the lower end of the operating range of 4500-5500 and is acceptable. However if you want to raise RPM---assuming you have checked and carbs are opening all the way--then try a prop with 2 inches less pitch. this will raise RPM by about 400 to 4900. If you do not have a stainless prop, simply switching from aluminum to stainless will add 200 RPM. Stainless is quite a bit heavier and stronger, the blades are thinner, and it flexes less. However, it will lighten your wallet a good bit more than aluminum.
Prop pitch is usually stamped on the side of the hub or inside, under the prop nut and washer. it will be something like 13 X 19 with the diameter being first and in this case 13 inches. So, if, for example you currently have a 13 X 19 installed, putting on a 13 X 17 will add 400 RPM.
