1990 Force 50 timing way off

mysteryboy28

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So I recently bought this 1990 Bayliner Capri 15 footer with a Force 50 motor. Guy said it ran great. Got my kids out on the lake, boat had a really hard time starting, wouldn't go faster than about 7 mph. Got it home, found it was only running on one cylinder. Eventually replaced the stator and trigger. Both cylinders sparking now, but motor runs bad, backfires and runs backwards for a split second. Get a timing light and find that cylinder one is firing about 90 degrees off! The 30 degree mark is blinking on the right side of the motor, rather than at the indicator mark above the carburetor. OMG. Lol. Cylinder 2 is even worse (blinking in a completely different zip code. Lol). Being new to 2 stroke outboards, I have no idea why the timing is so far off, or where to begin looking. When I replaced the stator and trigger, I'm like 100% positive I connected the wires exactly how the old ones were connected (which could have been wrong to begin with). This guy I bought the boat from clearly scammed me, and was probably tired of fixing the boat himself. TDC is correct, key is not sheared. I confirmed that I have the correct flywheel, stator, and trigger for this motor. Your help is appreciated. :)
 

mysteryboy28

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I think I fried my new timing light, trying to jump the starter at the starter relay (my helper was inside. Oops). Meanwhile, I messed with the timing advance lever and timing/throttle arm assembly, and seemed to notice improved responsiveness, Looking into setting things back to factory defaults. No clue how messed up it is now. Anyone know of a chart/tutorial that would help?
 

mysteryboy28

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I believe my situation is unique. The timing was off 90 degrees when I hit it with the timing light, but yet it's running. Lol. When I shorten the timing adjustment arm as short as it'll go, it seems to run better, but still bogs down and has no power. I've adjusted the air/fuel screw to specs, that made no difference. Fuel pressure is 8 psi, compression is 135 and 140 psi, spark is good and solid, it seems like the timing is the culprit. When I tightened the idle adjustment screw (the actual one), raising the RPM and timing, and shortened the idle adjustment bar to get a normal-ish idle speed- I can get some pretty sweet sounding RPMs out of the motor. But it seems like I have to do it manually, and it's still bogging a bit and takes a second to rev up. Does not sound like the healthy motors I've seen on Youtube (more like a verrrroooooggm, instead of a quick and snappy vroom!),. I'm running out of things to try. Head gasket is newer, didn't see any problem with it when I removed the cylinder head. Could the exhaust gasket be bad and causing weak performance? Looking for unique and less common causes of weak performance and timing issues. I used the wiring diagram and made sure the stator and trigger wires were where they needed to be.
 

Nordin

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Jun 12, 2010
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To set the timing you have to do it with a timing light. You can not set it by listen how it sounds.
As you have shorted the timing plate rod you have moved the spark advance.
With a timing light pointing at the mark at flywheel, checking the top plug at WOT the light should flash so 28 dgr mark lines up with the mark at the timing plate.
You do this with the plugs out, both plugs well grounded and at cranking speed.
Also check that the flywheel key is not shared.
If it is shared you can not time it right.
You can check the flywheel key by setting the top piston at TDC then the 0 mark at flywheel should line up with the mark at timing plate.
 

jerryjerry05

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May 7, 2008
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17,929
Sounds like your not doing the static timing recommended
by the manufacturer??

The backfiring could be it's sucking air someplace.

ONE!!! backfire can blow the port cover gaskets and make
the backfire/miss worse.

One of the biggest mistakes is the mechanic messes with the timing
because it seems to be off a little :(
 

mysteryboy28

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Guys, as I mentioned, key is not sheared, and the 3 timing lines (28, 30, 32) are blinking on the SIDE OF THE MOTOR, 90 degrees from where they should be! Plug wire #2 is even worse. I followed the procedure for checking timing properly. So something is really screwy here. This is why I asked about setting the throttle/timing linkage back to factory defaults giving me something realistic to start from, vs whatever this guy I bought the boat from did to it. Eek.
 

Nordin

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Strange, really strange.
You says it runs but only 7 mph.
With the top plug fire 90 dgr off it would not run !!!!!
Does the CDI module fire multiple times?
A 2 cylinder engine fires at 0 dgr and 180 dgr when no spark advance. A 3 cylinder at 0 dgr, 120 drg and 240 dgr.
A 4 cylinder 0 dgr, 90 dgr, 180 dgr and 270 dgr.
How confidence are your timing light? Does it pick up interference?

Must be something wrong with the timing light.
 

mysteryboy28

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I'll pick up another timing light and try again. But meanwhile, I'm out on the lake for another test drive. Advanced the timing some more, and it's running smoother, no stalling, but still only 7 mph. Revved up decent at home, but bogs in the lake. Any other suggestions (please read my previous posts to see what I've done/tested so far)? Thanks.
 

mysteryboy28

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Yes, as mentioned in a previous post. Stator and trigger were replaced twice with known working ones. Keep the suggestions coming! šŸ˜Š
 

mysteryboy28

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Flywheel looks great, is the correct one and looks to be intact and functional. (checked a bunch of pictures, just to be sure). Sorry for not elaborating on my answer.
 

Redbarron%%

Chief Petty Officer
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Dec 7, 2017
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You must go step by step or you are just pissing into the wind.
Flywheel FA658097
Trigger 888798
Stator 300-888793
COIL ASSY-IGN 300-888791

It is possible that although the triggers look the same you have one that is incorrect. If TDC occurs at the TDC mark and you can set the 30* WOT (plugs removed and wires shorted to ground). then the timing must be correct. If not you have a trigger problem,
It is alos possible that the trigger magnets have shifted on the hub, but unlikely.

. Disconnect the ball link to the carb cam at the timing tower. Disconnecting at the cam risks bending the cam. Move the cam away from the carb roller.
2. Loosen the screw(s) on the aluminum tie bar and let all carbs close completely, then tighten again.
3. Set the cam so that the scribed line is pointing directly at the black roller on the carb lever. If the cam has two closely spaced lines, set the black roller directly between them.
4. The black roller is held with an offset screw and nut. Loosen the nut and turn the screw until the black roller JUST touches the cam. Tighten the nut and re-attach the ball link maintaining the scribed line at the roller.
5. Adjust the ball link so that at full throttle the bottom carb butterfly opens substantially horizontally. Adjust the aluminum tie bar so all carb butterflies open equally at full throttle. They need not be perfect but should be rather close to horizontal for best performance.
6. Adjust timing to 30 degrees before top dead center at full throttle.
7. Adjust idle speed to 700-750 RPM in the water in forward gear. Do this with the screw on the bottom of the timing tower. Loosen the locknut and adjust. Screwing in increases idle speed. Do this in small increments and let the engine rev and adjust itself before the next adjustment. A little goes a long way here. When correct, tighten the nut. Note that the scribed line on the roller will now be (usually) below the black roller a bit.
8. NOW we adjust the mixture on the carbs. Set all low speed needles to about 1 1/4 turns out from lightly seated. Do not force as this will damage either the needles or the seats.
8A. With the engine idling in neutral, turn each the needles in equally about 1/8 turn at a time. Give the engine a couple of seconds between each adjustment to stabilize. Adjust until the engine either "sags" or stalls. Note this setting.
8B. Now go the opposite direction. Adjust until the engine runs rough, burbles, or stalls. Note this setting.
8C. Set all needles to the average between the two settings: That is, for example, if it stalled at 3/4 turn out and burbled at 1 1/4 out then set all needles to 1 turn out.
8D. Readjust idle speed to 700-750 RPM.
9. Take the boat out on the water and do a "hole shot"--Full throttle acceleration from a stop. If the engine "sags" then recovers and picks-up it is too lean. Open the needles about 1/16 turn at a time until the engine accelerates with no hesitation.
If the engine sputters or coughs or burbles, then clears itself and accelerates, it is too rich. Close the needles about 1/16 turn at a time until the engine accelerates smoothly.


10. I can NOT stress this enough! NEVER set the low speed needles less that 3/4 turns out no matter how poor the idle or acceleration. To do so will run the engine too lean and detonation and melted pistons at or near full throttle operation will result.
 

mysteryboy28

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Aug 2, 2020
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Thanks for the guidance. Learned something new a minute ago (just got a new timing light):

Cylinder one is firing with cylinder two! They're both firing around 180 degrees. Crossed wires, or something grounding? I followed the wiring diagram as best as I could (it was a bit blurry), and made sure wires weren't getting pinched. Any ideas what could cause that?
 
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mysteryboy28

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Aug 2, 2020
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Nope, triple-checked my wiring, and narrowed it down to a half-dead CD unit. Only pushing juice out one side. Swapped wires, and same result. White/orange side of CD unit is dead. I do however think something was getting pinched and crossing coil 2 to coil 1 (hence them firing at the same time). Rearranged my wiring so nothing crosses or gets pinched anymore. Got my eye on a replacement CD/coil set now... Why not replace em all? Lol. I can sell my used coils and recoup most of the $. Also looking into a regulator/rectifier upgrade.
 

mysteryboy28

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BAM - we got 25 mph! Way better than 7 mph. Lol. Bad CD unit was the problem. OMG, yay, I figured it out! Lol. But I enjoyed learning how to wrench on 2-stroke boat motors. Now to fine tune things and get 30 mph. :)

Kinda missing my 215hp Sea Doo jet ski (had to pull the motor to replace a magneto on that), and 255hp Sea Doo jet boat. But I'm still getting on the water!
 
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