1989 Mercury 60hp primary pick up adjustment

[Waverider17]

I own a 1989 Mercury 60hp 2 stroke and although this motor is almost vintage she's been very well looked after, serviced annually and owned by myself for 10 years. Long story short, due to some niggling issues last year, I carried out an overhaul of the fuel system, replaced the CDI box, coils, leads and rectifier and she ran perfectly for all of the 2022 season. I took my boat off its mooring in October last year and a month or so ago she just refused to start so I carried out some fault finding and found the trigger to be at fault. This was replaced along with the stator while the flywheel was off and she roared back into life.

I now need to check and adjust the timing and this is mainly because when she fired up the idle was a bit high, so I went to adjust it like I've done plenty of times before but my head was obviously elsewhere as I accidentally adjusted a timing screw just above. This didn't throw the motor out, she still starts and runs, just not that great and stalls in gear but I've been wanting to do a link and sync for a while and this where I came unstuck.

My Merc manual, like many, covers a lot of models and the information is conflicting. One picture labels the 3rd adjustment screw down on the spark arm as the primary pick-up with a timing adjustment, and the second picture labels the it as the secondary pick-up with a mechanical adjustment on the throttle cluster cam so I need to know which is the correct procedure for my motor. It would be great if someone could also confirm the link and sync procedure in case my manual is completely wrong. Any help would be greatly appreciated.

 

[Chris1956]

Gee, if you are working on a motor that old, you need the correct service manual, a not many shops will work on it.

The throttle arms changed a bit, but not that much since being introduced in the 1976-1980 model year or earlier. You should be able to figure it out with careful observation. Remember, the idle pickup timing is 0-9*ATDC. That is when the carbs just are ready to open. there is a set screw to adjust this. Likely it is in the midsection of the throttle arm.

 

[Waverider17]

She's an old girl for sure, but only 10 years use out of the box. This old Merc, along with other relics, was found by a family member in its original packing crate in 2013 in a corner of an old engineering Workshop that we had acquired at auction. It's just the conflicting information in my manual that's put doubts in my head and understandably for it's age I can't find a specific service manual.

I'm assuming that the adjustment screw in question adjusts the engine speed via the timing, which leads me to believe that it must be a primary pick up adjustment and not the secondary pick-up as it suggests in the manual. With my money on it being a primary pick up, would anyone be able to tell me which way to turn the adjustment screw to advance and vice versa? And would I start with the adjustment screw turned all the in or out?

 

[Chris1956]

The lowest screw on the throttle arm is likely the idle stop (speed) screw.

Primary pickup screw is usually just above the pivot point of the throttle arm.
You need to figure out which screw is throttle stop and which is max spark advance screw.
Max spark advance should stop trigger from moving before throttle stop stops throttle arm from moving.

Remove all the spark plugs except the top one and remove the prop. Put the motor in gear and advance the throttle until the carbs are ready to open. Install a timing light on the remaining spark plug. Jumper the starter solenoid and with the engine cranking (ign on), see what the timing is.

Find the primary pickup screw on the throttle arm and loosen to reduce timing or tighten to advance timing. Now advance throttle to max and while cranking, set the max spark advance to 21*BTDC,

 

[Waverider17]

Thanks for the information, you've cleared that up in my mind now. Does it matter where the primary adjustment screw starts? I honestly panicked when I realised I'd turned the wrong screw by mistake and don't know where I ended up, it's screwed in just over half way at the moment. Would it be better on the reduced side of ignition rather than advanced?

 

[Chris1956]

Just set the primary pickup and the max spark advance correctly. It doesn't matter where they are set now. If the set screw is all the way in or out, you have some other issue.

The throttle stop is to prevent the stops on the carbs from being bent, when the driver slams the throttle forward. Set them to allow the carb to open, but not be jammed open.
The idle stop adjustment is where the motor idles smoothly and wont usually stall, usually about 850- 900RPM. Slower is better, as it protects the gears from slamming.

 

[Waverider17]

Just set the primary pickup and the max spark advance correctly. It doesn't matter where they are set now. If the set screw is all the way in or out, you have some other issue.

The throttle stop is to prevent the stops on the carbs from being bent, when the driver slams the throttle forward. Set them to allow the carb to open, but not be jammed open.
The idle stop adjustment is where the motor idles smoothly and wont usually stall, usually about 850- 900RPM. Slower is better, as it protects the gears from slamming.

Thanks for the advice, it certainly helped me. Once you get your head around the link and sync procedure it's not that complicated and well worth doing as it's made a massive difference, especially to fuel economy in my case. She now idles smoothly at 850rpm in neutral and 700rpm in gear with smooth acceleration and much better hole shot up to 28knots on an 18ft cabin cruiser. Not too bad for an old girl!