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

[Of rib]

Yes, I had to adjust them all to match the SELOC image. The floats hang at an angle if I remember correctly. I forgot to take an "after" picture.

[transomstand]

Did the adjustment help?

[Of rib]

I can't say. I made that adjustment early on when I had multiple problems that I was working on at the same time. Most of my testing has been on the garden hose, I've only recently been able to get it out to a lake that I can open it up on and test all of the throttle transitions.

Would a float too low cause the engine to die when going from high idle in gear to neutral? Every freaking time I approach the dock and put the boat in neutral it dies. I just assume the same thing is causing all of my grief.

I've come so far on this engine, and now it seems I'm so close to solving the the last problem.

[transomstand]

Sure, a rich condition will stall it at idle.

This engine use choke plates or an enricher? Does it have an idle stabilizer?

[Of rib]

The engine uses choke plates and no idle stabilizer. Serial Number is 5025197 1978 Black Max

When I start the engine on the lake, I have to put the throttle control at about 1/3 to start it and keep it running, If I pull the control in neutral it dies. When on the garden hose I can pull the throttle back and it will idle all day long.
This means when I am approaching the dock and I need reverse, it just stalls when I hit neutral and I have to catch the dock with my hands to slow down.

[transomstand]

Did you do the full timing and synchronization procedure or just set timing for WOT?

[escape_225]

i had a similar prob with a 175 black max, ended up being a switch box that failed intermittently...

[Of rib]

I went through the entire sequence. Timing is spot on per the manual chapter 2C-7. (I used a dial indicator to ensure that the piston was at .462 BTDC)

[transomstand]

What's your max timing set at?

[Of rib]

it was at 18 degrees when I was cranking it. I think there is an 18 degree mark on my flywheel. That is where I set it.

[transomstand]

Increase that to 21°, I also want you to change your primary pickup screw to increase idle speed. What rpm does it idle at on the trailer?

[Of rib]

I will work on changing the timing tonight. What is the effect of increasing from 18 to 21 ?
The engine idles at 1000 rpm out of gear in the driveway.

[transomstand]

Timing increase will give it more grunt out of the hole and more top end too, will also have the effect of leaning out the motor a bit. I just want to be absolutely certain this engine has no "black boxes", idle module, advance module, etc. (I know I already asked about an idle stabilizer).

Also want you to run at least 91 octane fuel (even better would be 93), you don't need the extra octane but testing has shown that frequently we get less octane than what's shown on the pump and we don't need any detonation issues.

Then increase idle speed to 1200 rpm on the trailer using the primary pickup screw only, do not adjust the idle stop. Doing so will open the carb butterflies and that's the last thing we want.

At that point you'll be ready for another water test.

[Of rib]

this engine is bare bones, no black boxes of any kind!

unfortunately I have 10 gallons of 87 left in one tank. I suppose I could fill the other tank with 91 or 93, if I can afford it !!

OK, I appreciate the advice and most importantly, your time. I will make those adjustments and see if I can get it to the lake!

[transomstand]

Maybe just put a few gallons in the empty tank for the test, you can always reduce the timing again if you don't like the results and run on the 87 again. You'll know right away if it's improved.