1987 Mercury 60 ELPTO Prop Problems

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BigJake87

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Tulsa
LOCATION
Oklahoma
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New here and couldn't find an answer so I hope this is in the correct place..

I have a 1987 tracker tx17 with a 87 mercury 60 elpto. The motor starts and runs great but has trouble getting on plane and going over 20 mph. It takes around 60 seconds to go from 5 mph to 20 mph. I am working on moving two of the three batteries on the boat to under the front deck. I am also in the process of replacing all of the foam and wood in the boat to make sure its not water logged but so far its all pretty dry. I believe my prop is undersized, it is a stainless steel prop with the marking m70 p15 stamped on it, my hope is someone can help recommend a right size prop for my boat. Here is some relevant information from my research trying to find my answer.

Boat says it weighs 800lbs.
There are three group 27 batteries on board.
motorguide trolling motor on the front.
Outboard I am estimating at 250lbs.
Usually around 500lbs between me and my fishing buddy and gear (he sits up on the front deck when moving from spot to spot to help with weight distribution)
Compression shows "good" on the three cylinders 120-110 on each though I have not verified this.
Outboard shows 4800 rpm at WOT currently but my tach my not be correct.
Outboard starts easy and sounds like it runs strong.

I know it is old and wont be able to get anything crazy as far as speed but I would like to get on plane easier and maybe get 25mph if possible but at the very least I would like to make sure my prop is sized correctly. Any advise or help would be appreciated as I am new to boating and the equipment being so old I cant find any good information on what I am needing.
 
You've got something going wrong. I have a Tracker Tournament V17, a deeper and heavier boat, at one point it had an 84 60hp Merc like yours, it planed quite easily and would top out at 28-30. A 15 pitch shouldn't be too far off, mine was happiest with a 13 or 14.

Wouldn't hurt to go through and do a link and sync, and check the timing. Mud bees built a nest under the timing arm on mine one time, it wouldn't plane at all without those extra few degrees of timing.
 
You need to do a thorough check on your boat to start. Get a closer weight than a guess, repair or replace the tach so you know it is right. Do an actual compression test on the motor. What is the factory rpm rating at wot?? My guess is your motor is not up to par, need a complete tune up after compression test if it is good.. I have a 16' Sylvan SC with 3 group 31 batteries and a starting battery plus 15 gallon fuel tank and my fishing/ safety gear....my 40 hp Merc 2 stroke will push mine at 31 mph...powervtrim and the right prop makes a good running motor perform at its best. My boat is over 1000 lbs plus the motor weight.
 
You need to do a thorough check on your boat to start. Get a closer weight than a guess, repair or replace the tach so you know it is right. Do an actual compression test on the motor. What is the factory rpm rating at wot?? My guess is your motor is not up to par, need a complete tune up after compression test if it is good.. I have a 16' Sylvan SC with 3 group 31 batteries and a starting battery plus 15 gallon fuel tank and my fishing/ safety gear....my 40 hp Merc 2 stroke will push mine at 31 mph...powervtrim and the right prop makes a good running motor perform at its best. My boat is over 1000 lbs plus the motor weight.
I will get a Tach and see what it runs at when on the water. I have a compression tester already and i can see if my adapters fit correctly to confirm my self. Like i had said it seems to run well from how it starts up easy and does not bog or anything like that. I am getting my weights based on what forums say the factory weight is and the OB based off a new 75 HP 4 stroke.

I cant find much on the motor as far as WOT specs etc due to the age but i am still looking for more information. My neighbors with boats all seem to think the diameter of my prop is to small though I am not sure that's right. Unfortunately i have the decking pulled apart and it is icy out so it will be awhile before i can check the RPMs and stuff.
 
You've got something going wrong. I have a Tracker Tournament V17, a deeper and heavier boat, at one point it had an 84 60hp Merc like yours, it planed quite easily and would top out at 28-30. A 15 pitch shouldn't be too far off, mine was happiest with a 13 or 14.

Wouldn't hurt to go through and do a link and sync, and check the timing. Mud bees built a nest under the timing arm on mine one time, it wouldn't plane at all without those extra few degrees of timing.
I pulled the cover off of the engine and it looked fairly clean (theres oily residue and muck but not much considering its age and being a 2 stroke) i will look up a link and sync as i am unfamiliar with this term and will post an update. I am having trouble finding factory specs due to the age so hopefully i can find what the settings need to be and go from there.
 
You've got something going wrong. I have a Tracker Tournament V17, a deeper and heavier boat, at one point it had an 84 60hp Merc like yours, it planed quite easily and would top out at 28-30. A 15 pitch shouldn't be too far off, mine was happiest with a 13 or 14.

Wouldn't hurt to go through and do a link and sync, and check the timing. Mud bees built a nest under the timing arm on mine one time, it wouldn't plane at all without those extra few degrees of timing.
Just for Giggles i ordered a solas saturn 3 blade prop 3 blade 11 1/8 x 13 in stainless to see what happens.
 
I pulled the cover off of the engine and it looked fairly clean (theres oily residue and muck but not much considering its age and being a 2 stroke) i will look up a link and sync as i am unfamiliar with this term and will post an update. I am having trouble finding factory specs due to the age so hopefully i can find what the settings need to be and go from there.

Something definitely isn't right there.

Check that the throttle blades are opening fully, and at the same time. I'm not even sure that there is an adjustment on these, as the throttle shafts are joined together by a plastic coupler, which is very expensive, so don't break or lose it if you have it apart.

You'll also want to get a timing light and verify base and WOT timing, there should be a decal on the air box with those numbers. It's pretty simple, you can use the starter motor, pull the plugs, leave them in the wires and tie them up with wire so the spark has somewhere to go, and run the carbs out of fuel.
 
Something definitely isn't right there.

Check that the throttle blades are opening fully, and at the same time. I'm not even sure that there is an adjustment on these, as the throttle shafts are joined together by a plastic coupler, which is very expensive, so don't break or lose it if you have it apart.

You'll also want to get a timing light and verify base and WOT timing, there should be a decal on the air box with those numbers. It's pretty simple, you can use the starter motor, pull the plugs, leave them in the wires and tie them up with wire so the spark has somewhere to go, and run the carbs out of fuel.
The previous owner did spend sometime(a lot of time) working on the carb from what he said. Ill see what i can find. do you have any recommendations for a timing light and tach? Otherwise ill just get something from my local auto parts store.
 
The previous owner did spend sometime(a lot of time) working on the carb from what he said. Ill see what i can find. do you have any recommendations for a timing light and tach? Otherwise ill just get something from my local auto parts store.

I'm sure you can rent a timing light from any of the big auto parts chains. Sierra makes a good tach that isn't too expensive if you want a permanent option.
 

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