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1999 Merc. 40hp 3 Cyl 2 Stroke Timing issue

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WyattH

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1999 Merc. 40hp 3 Cyl 2 Stroke Timing issue: Trying to set timing using cranking speed method. 2 different timing lights indicate 12 Deg BTDC. Target idle timing is 2 Deg BTDC. I inspected the wood-ruff key and it is intact and tight. I replaced the trigger and flywheel with the same results.

I manually determined TDC using a dial indicator and 0 deg is exactly where I expected it to be on the flywheel right behind the timing tick.

I've only come up with 2 possibilities here.

1. I'm Stupid
2. I'm Crazy

In search of a cure.

Thanks,
Wyatt
 
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Timing on these motors does not go out of adjustment.-----What is your motor doing / not doing?-----What trouble shooting has been done ?
 
racerone said:
Timing on these motors does not go out of adjustment.-----What is your motor doing / not doing?-----What trouble shooting has been done ?
Click to expand...

Racerone, thanks for your response.

Customer complained of no WOT.

DVA and resistance checked CDMs #2 failed diode tests so it was replaced. Spark gap tests were OK.

Initial inspection showed lots of oil on the outside of power head, The top endcap seal had a little puddle of oil on top, seal replaced.
Noticed oil/fuel in carb throats pulled and serviced and cleaned carbs, and replaced reed valves.

This motor was previously "converted" to oil/fuel pre-mix and the oil pump pinion drive had been removed. It seemed to me that the pump membrane was ruptured as the oil pump was wet. Turns out that whoever converted the oiler used a natural cork stopper. I installed a neoprene stopper and ground the pump shaft down to effectively hold the new stopper in place.

There are 2 check valves on the crankcase cover and the plastic balls in them were gone, check valves replaced.

Bottom corner threads on crankcase cover had been "fixed" with JBweld. drilled/tapped for heli-coil but it didn't hold. Replaced cover with a used one.

New gaskets through-out for intake stuff.

When I put all that stuff back together, factory manual calls for carb sync and timing. That's where the trouble began, The new trigger is direct replacement for the old and I can't get the timing within 10 degrees of spec even with a new factory flywheel.

Wyatt
 
Was the stator removed and not re-installed in the correct orientation? If I remember, there are multiple hole patterns for different applications...
 
Fitz, Thanks for your idea and response the stator can only be installed one way, the front pair and the rear pair are on different centers, but it might be possible to install it upside down, I'll check in the morning.
 
BTW, I spoke to Mark in Tech Support at CDI Electronics. He said they ran into this issue in the early nineties when they started making replacement triggers. The trigger adjustment arm was interfering with the block and they made design changes to solve the problem. He also said that 10 degrees off on idle and WOT may not matter. I am skeptical but, I am sure that he knows more about outboard ignitions than 99.9% of the population.
 
The old trigger is marked:
855748A1
855746A1 is the OEM part number.
It's a 3 cylinder engine the new CDI trigger has 3 coils and the old trigger has 4 coils. 1 black ground and 3 wires 1 to each CDM I can't believe that it ran.
View attachment 29289
 
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