1987 skeeter 175-D and 1999 Mercury 200 EFI.

[JamesfromID]

I recently blew the motor i had on it which was a old mariner 175hp. With that motor, same prop, i was running 63 mph at 5600 rpms. The 200, same jackplate height, i ran 62mph at 5200. Raised the jackplate 1" and lost speed but gained rpms (57 @5600). Water pressure is at 12 psi right now. Prop is a 24 tempest. My elevation here is 3,000 ft above sea level. Holeshot isnt great. I carry about 30 lbs of tackle in the bow that i know isnt helping it lift which my boat has never lifted. I did have a 23 quicksilver prop that had no vent holes and it ran 61 @5400. I had it sent into have cup added and it fell on its face with 56 @ 5300. I tried a 23 tempest before i raised it and i had a better holeshot but lost 4 mph.

Kinda stuck on where to go. If i drop to a 23, ill gain more rpms and i will most likely have to drop the jackplate to make up for higher rpms.

Current setup.
1987 skeeter 175-D
1999 Mercury 200 EFI
24P Tempest
6" power lift manual jackplate
Motor is in the top mounting hole.
Prop has 3 medium prop plugs
Water pressure 12psi
Not sure pad height but i know it was at 3 and ive raised it a few times

This is WOT

[pmgoffjr]

Your motor sounds sick.

[KandKKustomz]

id agree.. i would be doing a compression test.

[JamesfromID]

Ive already had a mechanic do one and checked the motor out. Everything is good

[pmgoffjr]

Ok, just to make sure...
You didn't buy a 25" motor did you?
Anything else change? Did you add any transducers or other junk hanging off the transom?
There is something not right, you can't add 25 horsepower and lose rpms.

[JamesfromID]

Its not a 25".

Transducers are the same spot as it always been

[JamesfromID]

Theres is some issues though and why i had a mechanic go through the motor last week. When i step on the hootfoot to get on plane, itll hesitate for about 5 seconds fighting (sometimes itll die) before itll jus go like a bat out hell out of hell on plane. Sometimes itll hesitate idling when im graphing a area and die but mostly does it in the afternoon when its hot out.

And its a motor that has been oil pump delete and im running 50:1 premix.

Mechanic went through the motor and did a full service, comp test, leak down on both top end and lower unit. He also adjusted the throttle and shifter cable. Everything came back good

[pmgoffjr]

The results look like you're running on five. Pull the plugs and see if one looks wet.

[JamesfromID]

They all look like this.


Pic of transom


Pic of fuel filter

[JamesfromID]

Is 50:1 the right mixture for premix? It smokes at itle as well

[JamesfromID]

Also it has 3 med plugs in the prop. What does removing a plug do?

[pmgoffjr]

Plugs look fine
50:1 is correct.
Smoke is normal.
Here’s some cold truth.
Internet diagnostics is not easy. We can’t see it and you don’t know what’s missing. Not a jab it’s just the way things are.
Logic says if everything else is equal that the only answer is you’re down on horse power. Why? Get past the obvious and all you have left is a wild guess.

Which I won’t do.

[JamesfromID]

I simply asked about the prop plugs. Im not sure why you seem to jus want to be an ass.

[pmgoffjr]

Ok
You described putting a deuce on and losing speed and rpms.
I asked the normal quick things to look at.
Prop plugs have zero effect on top end.
Sorry to hurt your feelings buttercup.

[mdtritn21]

That old 200 efi will turn 6000 rpm's all day so don't worry about rpm's but at 3000' I'd put a known good 23" tempest on it and with medium PVS plugs and run it. 12 lbs is all right for WP at WOT but it will never have a good hole shot, that motor if it's a 2.5 is a hole shot turd and always has been.

[JamesfromID]

As of the other day, i removed one plug and it gets right up on plane quick. Even with two people. So i have that figured out. Now its jus playing around with the top end.

[jarhead175]

You should have zero hesitation from that EFI. Might make a post on the Merc form and see if on of the guru's can help you but that motors not 100% if it has a hesitation. I ran one for sixteen years and it never skipped a beat.

[Garfish]

The pic of your jack plate appears to me to be high, usually that indent at the top of the plate is just under or snug to your transom trim cap. Just a thought

[JamesfromID]

I had asked the mechanic to bring it down a bolt hole and i guess forgot to do it.

Took all my tackle out and put it in the rear and now im getting 62mph @ 5600 rpms. 1/2 tank of fuel and just myself (6ft 250 lbs). Rooster tail is foot above engine cowling and my holeshot is pretty damn quick. Removing one plug out of my prop helped really well with holeshot. Not sure what speeds i should be getting with this 200 efi or am i maxed out speed wise.

Only thing now is after i trim all the way up at WOT, the front starts porpoiseing and gets worse as i go. I can trim down and itll stop but i lose speed. Or, while on pad and WOT, i can rock it side to side and itll stop for about 5 secs and start doing it again hopping down the lake. Haha. This is still with my 24p tempest.

[jarhead175]

It's called chine walk you need to find someone that knows how to drive a boat at speed and have them teach you how to drive. People can tell you how to do it but until you see it done and feel what is happening you will struggle with it.

Don't set a boat up with a light load. When you fish with someone or with a full load you will hate your ride. Always set up full load, two adults, full of fuel, and live wells full. Get the boat to run loaded and it gets better on light trips.