I am getting 5000 rpm's top speed full trim, I believe it should be between 5400 and 5600 am I right ?
mercury black max 19 pitch prop. If I went to a trophy plus 4 to get more lift what pitch shoudl I start with ?
since getting my boat back from the factory for hull repair, the tach moves all over the place, does not hold a steady reading and at times goes to 6ooo rpm's which I doubt can be right

My 1998 mercury 115 states max RPM's at 5250. You may be closer than you think.

My 1998 mercury 115 states max RPM's at 5250. You may be closer than you think.

with 5000 rpm's with 19 pitch aluminum prop, do you think I should go to 17 or 19 pitch in a trophy pls 4 blade prop ?

4750 -5250 rpm's for the 2 stroke 115, tried the 17p trophy II but the rpm's at WOT were a bit too high (5500) went to a 20p laser II and picked up a few more mph. I have an 18' aluminum hull and I get 44 mph @ 5100 rpm's gps and the hole shot with the plugs removed will put you in the back of the boat. Look on eBay you can pick up one like new for about 200.00. You'll get the lift you want witht he laser prop, I couldn't tell the difference between it and the trophy.

Rebs, 5250 is max rpm for that motor. You most likely won't be able to over rev, as mine had a rev limiter on it.

For the wandering tack, see if the wires are mounted tight on the back of the tach. If so, how good are you with a voltage tester?

Rebs, 5250 is max rpm for that motor. You most likely won't be able to over rev, as mine had a rev limiter on it.

For the wandering tack, see if the wires are mounted tight on the back of the tach. If so, how good are you with a voltage tester?

I will check the wires on the back of the tach, I am comfortable using a volt meter.