Timing

[waterboy84]

Ok so im trying to set timing on my 120hp force. I understand its gotta be set at 28degrees btdc. My question is being the trigger control arm that connects to the tower shaft is almost a inch wide what part of the trigger control arm do i use to set the 28 degrees at. Or do i set it at the middle of the triggers control arm. Im not seeing any marks on the trigger control arm as the tick mark on the crank case to indicate tdc. Any info is much appreciated. Just want to make sure i get this timing set right so i dont loose a motor. I will post a pic to show what im working with. Thanks for the help.

 

[waterboy84]

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[SkiDad]

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you use that mark on the plate in front -see updated pic. You set this when cranking it with throttle in full throttle position. depending on which year you have to actually set the timing differently when cranking - i think on mercury ignition you set it for 32 to get to 30, while on Prestolite ignition you set it at 28 to get to 30. you didn't say the year but that looks like a mid 90's model which is most likely mercury ignition. Don't forget to tighten lock nut when done (but just a little bit since this is plastic)

see video: https://www.youtube.com/watch?v=o1HmYyOQFW8

 

[jerryjerry05]

Why are you adjusting the timing??
​Unless you change the trigger the timing usually doesn't need any resetting!!

 

[waterboy84]

Thanks skidad for the info. However the coil packs do say mercury and the switch box says mercury so yes it does look like i have mercury ignition. As far as the exact year. I do not know exact year of this motor. My boat however is a 1995 maxum so im pretty sure this is the mid 90s motor as you said. Ill post a pic of it to show you maybe if you seen it you could give me a idea of what year it may be. Now to jerryjerry. Only reason im messing with the timing is becuz a few months ago my wife and kids and i was out on the lake and the boat just died and from that point it never started again. So after researching and reading up on the syptoms i was experiancing i was thinking the stator or trigger went bad cuz i had no spark at all. So i was gonna replace both stator and trigger so i removed flywheel and removed trigger and stator. After removing those 2 ignition componets something told me to post on this web site my symptons. And so one of the experts on here i forget witch one it was gave me some step by step things to check for and test and after doing all that he tolx me stator and trigger turned out to be good. It was the switch box that failed so i bought a new switchbox put everything back together and what do you know motor fired right up. I took it to the lake a few times after i got it running again. The motor runs fine. Well to me it does. However im having a low speed (idling) issues. When boat is just in gear at idle it sometimes just dies. But it will fire right back up. Also when you put it into gear and take off. The motor sounds i guess you could say weak like it has alittle bit of bogging down you could say. But while the motor is sounding weak and sounds like it boggs alittle the motor doesnt loose power it keeps on pushing the boat through the water. Motor runs good and sounds good when running full throttle. Its just at idle low speed. I know the air mixture could be a factor in this issue as well but i took boat to lake a week ago and spent 2 hours on the water playing with the air mixture. I had air mixture set at 1turn out 1 1/4 turns out 11/2 turns and all in between and its just not right. Thats why i believe the timing isnt right and so i just wanna gather some info together on getting a step by step guide on makibg sure timing is perfect. I know when i took that trigger off that i wacked out the adjustments it was already set at. Another thing. Tell me if im right or wrong. My boat tops out at wot at 4500rpms. Is that right or should i top out at more. I read a few things that a 120hp force should top out at 5500rpms. My boat is running only 35mph. Does that sound right.

 

[waterboy84]

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[waterboy84]

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[waterboy84]

Also i want to mention that not even a month ago i replaced all fuel lines. Every fuel on the motor and the fuel line from the motor to the tank are all new. I even replaced the fuel filter with a new one. I also took both carbs apart and cleaned them. When i took carbs apart to clean them i was really amazed on how clean they looked inside. I even put new float bow seals. Not that they needed replaced i just like putting a new gasket/seal when separating 2 things from a gasket/seal.

 

[SkiDad]

whenever you increase the turns out on idle speed you have to raise your idle speed - that is the screw at the bottom of the tower. You put the boat in gear on the lake and raise it slowly till you are about 750 rpm steady. Then tighten that lock nut.

of you haven't moved the timing yet you could just check it - i can check the book at home for the timing - but I think you want it at 32 while cranking.

 

[waterboy84]

I would appreciate it cuz thats where im confused. Not knowing the exact year of this motor and im seeing 28 degrees 30 degrees and 32 degrees. I have the switchbox ignition. Someone told me sense i have the switchbox ignition my motor has to be a 90-94. Does that sound right to you. And im pretty positive my timing got alittle wacked out when i remove trigger as i mentioned in one of the last post. When i took the trigger off i removed the nut and bolt where the tower shaft connects to trigger and dummy me one i was conversating with my brother not paying attention and i was messing with it and was unscrewing it from the adjusting screw and when i realized what i was doing it was to late i had already unscrewed it and didnt even know how far it was screw onto the adjusting screw. So yes i did knock the timing out of place for sure.

 

[SkiDad]

i looked in my book and it's 32 degrees at cranking for the thunderbolt ignitions. I sent you a PM with other info.

also, as for the age of your engine, you have a Mercury lower unit so it's at least 1995. 1990-1994 had a Chrysler lower unit. Maxum and Bayliner packaged these engines so there is no reason to believe it's not a 1995 as well.

as for speed i would think that boat should hit 40, what pitch prop are you running - a 17 for serious water sports or 19 pitch for overall use would typical. You should be hitting around 5000-5200 rpm

one last thing to check, with the engine off, put the boat in gear and push it forward all the way - make sure your carb butterflies are flat.

 

[jerryjerry05]

You need to take a breath between sentences !!
​See how SkiDad has spaces between the sentences?

​Very hard to read and follow.

Do a compression and spark test.
Post the results.

 

[waterboy84]

Thanks skidad for the info. Very very helpful.
One last question.
When setting the 32 degrees. What side of the trigger control arm do i use to set the 32 degrees on
Or do i set it in the middle of the arm.

 

[SkiDad]

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look at the video i linked - you need to ground spark plug wires and bypass a few things and then put the throttle in full throttle position.

you hook a timing light to your battery, then put the inductive pickup lead on the top spark plug wire, you aim the timing light at the flywheel...

when you have someone cranking you check the marks on the flywheel in relation to timing marker i pointed out on the other picture... then stop cranking for a second and make an adjustment to the screw in this picture and re-check. Repeat until you get it correct.

 

[waterboy84]

Do i only use that one spark plug wire to set timing or do i have to do it to all 4 wires

 

[SkiDad]

just top wire, but all wires must be removed from spark plug and grounded - you don't want it to start, nor do you want to damage any CD boxes.

 

[waterboy84]

Skidad. I just want to update the status of the timing and explain what i did and make sure i did everything right.
Well first off. After playing with the timing light i had for about a hour in a half i finally realized that timing light didnt work on my 2 stroke motor. So aggravating.
So i went and bought another timing light making sure it would work on 2 stroke motor.
Came home hooked it up and what do you know. Everything worked.
Ok so im gonna post a pic but first i would like to explain what i did.
I took out all 4 spark plugs. I bought some 10 gage wire and jammed the wire in all 4 plug wires. I then grounded those wires to the battery ground mounted on the engine block. I bypassed neutral safty switch. I put throttle control all the way forward at wide open. My wife then cranked motor and i observed. Timing was off and it wasnt at 30 degrees as you stated it should be.
So i then made adjustments and it now fires perfectly on 30 degrees.
Did i do this right.
Im gonna post a pic.

 

[waterboy84]

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[SkiDad]

you did everything right but I think you wanted 32 degrees. from my reading of the book on mecury ignition you set it to 32 at cranking but it translates to 30 when you are actually boating.

 

[waterboy84]

Great. I can make that adjustment and set it at 32. Right now it fires dead on 30. I did see that in the pic of the manual you sent me but i was confused. I will make that small adjustment not a problem.
I want to give you a big thank you on the knowledge you gave me and for your time helping me gather some info. You was a big help to me and it was much appreciated. Thank you.