1986 200 Merc (carbs) performance issues

[jh4rt]

Hi.
Took the boat out today after raising it up on the transom. The center of the prop shaft is now about 3" below the keel (20' Schiada). In testing it, I started out running 59.8 mph on GPS at about 5600 RPM. Later, the engine started "bogging" at about 5400 RPM and would only pull about 50 MPH.
I have no idea what is going on. I went home and did a compression check. All cylinders at 123.
Any ideas what is going on? The service manual lists a high speed timing advance module, could that be the issue? The only thing is... now, the engine gets hot above 5000 RPM???
Did I lunch it?
Also, if anyone knows of an ACE merc mechanic in the Southern California area, I'm in need of one.
Thanks,
--jh4rt

[Tom Brown]

There might not be anything wrong with your engine.
There is a point where your gear case will try to plane and that will push the bow down and cause you to lose performance.
What happens when you move the motor back to where it was?

[Riverkid]

Do you have any pics of your current setup, on the trailer? I'm considering changing the setup on mine (21RC w/ '87 200) and am interested in what your findings are.
Thanks. :)

[jh4rt]

There might not be anything wrong with your engine.
There is a point where your gear case will try to plane and that will push the bow down and cause you to lose performance.
What happens when you move the motor back to where it was?
I only raised it up. It used to be really deep and really wet. The engine is mounted in a well directly on the transom. As well, it had a 6 degree wedge, which I also removed. The performance is a lot better. I haven't lowered it back down. It would certainly go slower.
As far as the bow, it carries the bow really well at this point. As I go faster, it doesn't seem to lower the bow or try to bow-steer at all.

[jh4rt]

Do you have any pics of your current setup, on the trailer? I'm considering changing the setup on mine (21RC w/ '87 200) and am interested in what your findings are.
Thanks. :)
Mine is in a well, so it might be a little different. I will take some photos and post when I get a chance.
Any advice on a mechanic?

[Riverkid]

Jim Wilkes is pretty good (714) 540-8908. He did all the bal and blueprint work on mine, hyd steering, cav plates etc. It's held up through the test of time... He's been helping H20ski2fast with his OB lately and they've seen some nice gains...
Plus he's got Irvine Lake to test on... :)

[Tom Brown]

I only raised it up. It used to be really deep and really wet.
Yes. I understand that.
What I don't understand is that you made a change, the boat ran slower and began to overheat, but you don't seem to know what the cause is. Maybe it's the change you made?
I know this... As I raise my engine, there comes a point where the gear case will try to plane. It is at this point that the planing gear case will push the bow down and cause a bunch of drag and load on the engine. Lugging an engine will cause it to run hot. The steering will also become sluggish as hell.
3" below the pad is a no-go zone on my boats. I need to either run it fully burried or somewhere between even with the pad and about an inch up.

[h2oski2fast]

It may be overheating because it's not getting enough water at that height. Especially if you dont have a low water pick up. Not sure if you have a water pressure gauge, but I feel you need to know what the water pressure is while driving. It may also help to determine where the overheating problem lies.

[jh4rt]

3" below the pad is a no-go zone on my boats. I need to either run it fully burried or somewhere between even with the pad and about an inch up.
OK! I'm pickin' up what you are laying down now. To run it that high (even with the pad) do I need a low water pickup? At that point, should I be moving the engine back off the transom?
Thanks for the help!

[h2oski2fast]

Jim Wilkes is pretty good (714) 540-8908. He did all the bal and blueprint work on mine, hyd steering, cav plates etc. It's held up through the test of time... He's been helping H20ski2fast with his OB lately and they've seen some nice gains...
Plus he's got Irvine Lake to test on... :)
Yep, it pulls a skier up now. LOL :crossx: :crossx: :crossx:

[Tom Brown]

To run it that high (even with the pad) do I need a low water pickup?
Yes. Also, like h2oski2fast said, get a water pressure gauge. They aren't a lot of money and it will save your engine.
At that point, should I be moving the engine back off the transom?
Setback usually helps but it varies from boat to boat. There should be lots of people with Schiada outboard experience who can tell you what the optimal setback will be.
I would consider just dropping the engine back down. It should work the way it used to.
When you decide to go for more height, get a jack plate, water pressure gauge, and low water pickup nose cone.

[h2oski2fast]

OK! I'm pickin' up what you are laying down now. To run it that high (even with the pad) do I need a low water pickup? At that point, should I be moving the engine back off the transom?
Thanks for the help!
Each boat is different, but when moving the engine back, you need to raise it up. A general rule would be for every 2" back you go, you need to go up 1". By moving the motor back it will help get a better leverage point. You might also want to check out www.screamandfly.com there are lots of OB people there. This is the 1st OB I have really played around with, so I dont get into the workings of the motor (although I do understand how they work), I let Wilkes Marine handle that.

[Riverkid]

Rut Roh....
Using that formula, Dennis, my motor is about 22" too low... :rolleyes: :)

[jh4rt]

It may be overheating because it's not getting enough water at that height. Especially if you dont have a low water pick up. Not sure if you have a water pressure gauge, but I feel you need to know what the water pressure is while driving. It may also help to determine where the overheating problem lies.
It was running about 15 lbs. It dropped to about 10 momentarily, but then I trimmed it back in. When it was getting hot in the afternoon, it was actually running 25 lbs.

[h2oski2fast]

Rut Roh....
Using that formula, Dennis, my motor is about 22" too low... :rolleyes: :)
Maybe! :idea:

[h2oski2fast]

It was running about 15 lbs. It dropped to about 10 momentarily, but then I trimmed it back in. When it was getting hot in the afternoon, it was actually running 25 lbs.
Sounds like there could be a thermostat problem.

[Boat Racer]

if you could go back to the old set-up, with out alot of trouble or time I would, and see if problem continues...

[jh4rt]

Well, I took the boat to M&K Marine in El Segundo. Miguel and Kathy are great to work with.
He found a piece of "silicone" in the #5 carb. That cylinder was leaning out causing both the overheating and loss of power.
It is making full power on his dyno now.
Thanks everyone for the info.