1978 Black Max 150hp 2 stroke - Bogs down when accelerating

[Of rib]

Greetings Guys, this is my first post here, I have posted on other forums, but it was recommended that I post here as well.

Trying to determine why my engine bogs down when trying to accelerate and why it normally dies when returning back to idle from high rpm's

What I know:

All 6 cylinders have good compression (My gauge is analog, but they all read very close to 110)
All 6 cylinders have blue spark that jumps a minimum of 7/16 on the test tool
All new vacuum lines installed
All new fuel lines installed
Spark plugs/wires are good
No slop in the throttle cable
Throttle linkage adjusted per the manual
I have checked engine timing and it is correct
Carbs (WH2-1) have been dismantled and cleaned - Jets were removed and cleaned (The floats were adjusted, but the floats and needles were not replaced)
Fuel is 50:1 mixed in the tank
The engine reaches 5500 rpms at WOT (It just takes some time to start accelerating) WOT video: http://youtu.be/IbnuWRzUu9g
The engine does not miss or stumble at WOT
The RPM's hold at 3000 for what feels like forever, then you can hear the engine start revving up and the boat goes on plane.
The fuel bulb gets firm when I pump it, I can squeeze hard and force fuel to drip out the lower carb (This might be an indicator to my problem)
There is a lot of raw fuel in the carb cover when I removed it after a day on the lake
The engine idles great when out of gear and on the garden hose
The engine bogs down when put into gear, I have to make sure i give it plenty of throttle to avoid killing the engine
The engine will die when returning to idle from high rpm's
The engine smokes a lot at idle


It seems to me that too much fuel is my issue, If I can force fuel out the carb by pumping hard on the fuel bulb then I'm thinking that must be my problem.

I must be flooding the carbs, I don't know what else it could be ?? Could the old stator cause this problem?

Thoughts?

(Oh how hilarious, my username should have been Ogriv, but it looks like spell checker changed it to "Of Rib" )

[Of rib]

I put together a short video showing the engine starting, at idle speed and the boat trying to plane:
http://youtu.be/c2ICvN877aY

[BigJohnson]

Is this a new setup or an existing setup with a new problem?

[Dave Strong]

Start with needle and seats, should be able to hold back the primer ball.

Dave

[Of rib]

This has been an ongoing problem since I bought the engine 3 years ago. I have been repairing it in my spare time using parts from a disassembled black max from the late 80's.

So there is no way I should be able to force any fuel through the carb no matter how hard I squeeze the priming bulb? I checked the floats when I cleaned the carbs, they looked old but I could not locate a replacement so I just adjusted them using the service manual instructions.

[Dave Strong]

Sounds like the needle and seats are not sealing.

Dave

[transomstand]

I checked the floats when I cleaned the carbs, they looked old but I could not locate a replacement so I just adjusted them using the service manual instructions.

There are no replacements, the early V-6 uses the "round bowls" and they are looong discontinued. You can upgrade to a later set of carbs with the "squared" bowls, they also use floats that are discontinued but with sufficient scrounging they can be found.

[j_martin]

This has been an ongoing problem since I bought the engine 3 years ago. I have been repairing it in my spare time using parts from a disassembled black max from the late 80's.

So there is no way I should be able to force any fuel through the carb no matter how hard I squeeze the priming bulb? I checked the floats when I cleaned the carbs, they looked old but I could not locate a replacement so I just adjusted them using the service manual instructions.

They should hold back about 10 lbs, which is a firm handshake on the primer bulb. A white knuckle grip will overcome good ones. I think yours are OK. If you have foam floats, they might be a bit heavy. You might be able to compensate by setting the floats slightly low. Best solution is get a set of carbs with the hard plastic floats, maybe off a late 80's early 90's 150 and set them up. Jets vary widely by carb, so go with the original jets to start with, but do some full speed shut offs and read the pistons to be sure it's getting enough fuel at WOT.

If it's running good otherwise, I'd also guess you're slightly over-propped. Let it spin 5800 or so.

(update -- I just watched the vid)

Do you trim it in fully for the hole shot? Your boat is heavy in the back, as it should be. (2 or 3 batteries, fuel tank, fish swimming pools, etc.) You need to tuck the motor under to get the nose down, then trim it up as it goes on plane. It doesn't sound like it's bogging much, just overloaded.

[Of rib]

The engine is trimmed fully down when I try to accelerate. Once it gets on plane I start trimming it up, and actually get a rooster tail sometimes when I near 5500 rpm's.

The prop is a Quicksilver Laser II and it is stamped with 22p, so I assume that is the pitch?


Pictures of my floats:




I do have a set of carbs off of the newer engine, but it looks like the air box would have to be modified.

1978 Carb = 1382-6425 WH2-1
1990 Carb = 3308-9672C WMH 1

[Of rib]

Here are some pics of my plugs. I think they look normal.

[Of rib]

[Of rib]

I looked in my service manual and located the test procedure for the Stator and Trigger assembly. I'll get some Ohm readings to see if it's something obvious. I don't have a DVA meter, so I'm left with Resistance measurements rather than voltage readings.

[transomstand]

Those are the ancient round floats you can't get.

Are the floats hanging in that photo?

[Of rib]

Yes, they are hanging in that photo (That may be the "before adjustment" picture). Per the instructions, they are set at 1/16" as measured at the location depicted the picture below from SELOC.




But I reviewed the float adjustment procedure in the Mercury Service Manual (section 3-13) and it show the 1/16 being measured at the end of the float and not the midpoint ??????




I tested my Stator and Trigger just to rule them out:

[transomstand]

Yes, they are hanging in that photo (That may be the "before adjustment" picture). Per the instructions, they are set at 1/16" as measured at the location depicted the picture below from SELOC.




But I reviewed the float adjustment procedure in the Mercury Service Manual (section 3-13) and it show the 1/16 being measured at the end of the float and not the midpoint ??????

That should have made quite a difference from where they were, did it change much? Also, you want to be sure the floats are relatively even with the carb body when the needles are closed as shown in the photo.