86 Merc 60 horse, cannot get under 2000 rpm!

[danalex]

I finally got my 60 running on all cylinders, is smooth and sounding good, but it is idling at 0ver 2000 rpm. Was at 2500 and I adjusted the spark stop and idle stop enough to get it to 2000. Now I can mess with the idle speed jets and make it run rough enough to get it to around 1500 rpm but that is just wrong. Any ideas will be appreciated. I have disconnected the throttle cable and the lowest I can get it is 2k. Butterflies are closed.

 

[jimmbo]

Idle speed setting is done strictly by retardation of spark timing. Are you using a service manual(preferably factory model specific) to guide you as to what adjustment screws affect what?

 

[danalex]

I don't have a service manual. I would love to have one. This is a 1986 mercury 3 cylinder 2 stroke. What I can see is...The spark is advanced or retarded by moving the trigger, which is a coil lying under the flywheel with the stator. The flywheel spins clockwise. To make the magnets on the flywheel pass the coil earlier will advance the spark, if they pass the trigger coil later that will retard the spark/timing. A bent metal rod connects the trigger to the throttle arm. I can see it move when I adjust the spark adjust screw.
A different curved metal rod connects the throttle arm to the carb throttles. I have the roller for that arm about .020 from the actuator to make sure the butterflies are closed.

Looking at the throttle arm from the (using car terminology here) driver side, Moving the spark advance left should retard the spark, moving right will advance it. With the spark advance as far to the left as it will travel the motor is running at 2200 rpm.

Idle is set as low as the arm will let it go.
Spark as far retarded as screws the enclosure under the flywheel will let it go.
Butterflies are closed and move in sync. Not touching the accelerator roller at all, .020 clearance.
I connected the coils back the way they were originally.
Next step maybe....disconnect the spark advance and see if I can get it to slow down without that connection to the throttle arm.

To restate, with all the adjustment screws backed off to allow free movement, I can hold the throttle arm and move both pieces (Spark and carb control) either direction. There are 4 possible combinations of movements. All 4 either speed it up or do nothing.

Carbs are tuned so that I get instant response to the throttle, quickly snatching it wide open surges. I enriched the slow speed screw by opening it up 1/4 turn to make sure I am not too lean.

I never had an engine run too well before. I do not want to shift this engine till I can slow it down.

 

[danalex]

I put the old main needle valve and seat back into the bottom carb. No change. Still running at 2 - 3 thousand rpm.

 

[danalex]

While it was running I sprayed carb cleaner around the flange where it connects to the block, it made the motor slow a little which should mean it was leaking. Pulled it off and used permatex on both sides of the gasket to seal it and re-installed. Checked the fuel pump the same way and found a leak there as well, that was unexpected. But I pulled the fuel pump and permatexed every join and gasket. Put it all back together and cranked the motor up. It was running too fast, but better, about 2500 rpm. There is a steady stream of fuel coming out one of the little pipes in the carb. I put my finger over it, about about this time I realized I had not turned on the water. Shut it down and grandson has my wrenches so will change impeller in water pump tomorrow. I cranked it with the water on and no water flow of course.

 

[danalex]

jmmbo, do you have access to a service manual or can you point me in the direction of one? I believe I have the relevant passages on link and sync but I am totally willing to learn.

 

[danalex]

I have installed the new water pump and housing, the old housing has some plastic melted...it got pretty warm. About to go out and crank it and see if it has healed in the past few days.

 

[jimmbo]

jmmbo, do you have access to a service manual or can you point me in the direction of one? I believe I have the relevant passages on link and sync but I am totally willing to learn.

It's not the factory manual
http://162.144.28.33/lib/mercury/manuals/mercury_1965-1989_40-115.html#/240

 

[danalex]

Thank you very much, incredible! I have printed some pages and will use them. I will share these with another poster who is trying to get his idle up, and tell him about you.

 

[danalex]

I have the timing perfect and it still runs high. I took it to the water to check it. It runs at 2k rpm at idle in the water. I started it in gear and ran it for 2 hours, very slowly adjusting idle screws - got it to 2600 rpm in gear. Adjusted spark. Got it to 28k. Adjusted back and forth, very slowly, sprayed a little seafoam to to point of killing it every now and then. Wound up at about 3k rpm, could not get it higher. I took the idle screw completedly out of the bottom carb while running at 3k rpm and there was no change. I suspect the bottom carb needs more work. I put a new enrichment valve on both carbs, it was leaking air severely on both of them. I would love any advice anyone has.

 

[444]

Follow the link and sync procedures in your manual. If the one linked isn't right for your motor, just buy the Clymer manual, it will have the procedure in there as well.

If after that you are still idling too high, you have an air leak somewhere. It could be at the carbs, could be at the intake manifold, I've fixed leaking crank case halves and leaking crank seals. Two strokes are very sensitive to air leaks. Permatex isn't the solution, I have always found correct gaskets to be the best. I have tried sealing two stroke crank cases with permatex motoseal grey, which IIRC is the only one rated for gasoline contact. I didn't have much luck with it and I have switched to using threebond for my crank case halves and proper gaskets where there are supposed to be gaskets. I have a hand held vacuum/pressure pump so on engines that cause me grief I make block offs for the carb flange and exhaust and vacuum/pressure check the crank case.

Also check all your fuel line connections. They should be clamped with gear clamps. I have made old two strokes from the 1950's and 60's run like new by being diligent on these sorts of details.

 

[danalex]

Thank you! I hope you come back and read this, I think you are exactly right. I have the manual and followed the link and sync, the motor was running way too fast. So it has to be getting air into the crankcase somewhere. I checked the throttle shaft today and it is worn, there is only a brass washer on the top of the carb (Just talking about the lower carb right now). There is enough clearance between the shaft and the washer to see light. On the other end of the shaft is a seal. It is stiff so I assume plastic, it fits fairly tight. I have been thinking of trying to make a better seal than the brass washer using epoxy. A spring sits on top of the washer. There is not a lot of pressure holding it down. I have been looking at replacement carbs, I suspect getting a used carb might give the same problems though. Thoughts or advice?

 

[danalex]

Oh, I have replaced all the tie wraps on the fuel lines with screw driven clamps that are a little more reliable. I also checked the float on the bottom carb(Perfect at 11/16) and replaced the needle valve, seat and the little washer under the seat. (It was sticking) I used cue tips and cleaned out everything I could get it into, blew it out with seafoam. Made sure I had no threads from cleaning. Made sure the float didn't contact the gasket or the bowl, I read about that elsewhere. It moves freely, I blew through it and made sure it opened and closed correctly before I put it back together.

 

[444]

Sounds like you're on the right path. If you're sure the carbs are closed and the timing lever is all the way back then you gotta be leaking air somewhere.

 

[danalex]

I sealed the carbs and one at a time, with them off the motor, blew smoke into them. Discovered the bowl was leaking on the bottom carb, massive leak. Fixed that. Had a leaky fuel hose. Fixed that and checked all the other hoses with smoke under pressure. Attached carbs to motor, sealed and blew smoke. A small hole in the top of each carb, a factor hole, is leaking smoke. I do not know if it should be open or not. I started the motor and it runs slower, about 1500 rpm. Stopping up the hole in the top of the carbs makes no difference. Did not get smoke out of motor when I did the smoke test, none from under the flywheel or where the head is mounted, thank god, maybe not a seal. Now leaning toward flywheel has partially sheered the key and rotated a little. Ordered the tool to remove flywheel, will be here thursday maybe.

 

[danalex]

factory hole. Above post reads odd.

 

[jimmbo]

You set the max timing at cranking speed at WOT(no sparkplugs installed and plug wires grounded, to prevent a fire), then you pull back the throttle to set the primary pickup timing(what the timing advance is when the throttle plate is just about to start opening), then you retard the timing(by pulling back throttle linkage) until you get the proper Idle speed, in gear, in the water, with a the prop installed.
For all of this, the throttle cable from the remote should be disconnected at the motor. Once Idle speed is set, the throttle cable man need to be adjusted longer or shorter do it provide a little preload against the idle stop.

 

[danalex]

I will do this - just read it several times to make sure I understand. It is not pumping water to my satisfaction so I am gonna change the impeller and check the gaskets and pipe linkage. I had to replace the base of the pump when I cooked it the other day, bottom seal was leaking so I replaced the oil in the foot as well.

By the time I get done with that maybe the flywheel puller will be here. With the motor running in the water, prop on in gear, throttle cable disconnected at the motor, butterflies fully closed the motor will not idle down past 1500 rpm. I adjusted the idle mix screws till I got best sound, then opened up till it staggered and then tightened back up till it smoothed out, left it a little rich. I then retarted the timing till the timing lever hit the stator housing and would not go any further. I checked for blowback out the carbs a few times, no blowback. Both carbs sucking, feels the same to my hand. Motor chokes down if I obstruct the either carb with my hand. No leaks detected on carbs, fuel lines or block using pressurized smoke. (other than the small, 3/16 inch brass lined hole on top of each carb). Throttle body not leaking. Butterflies are tight in the throat, looking up at light thru carb there is no light around the butterflies. New enrichment valves, they aren't leaking.
I fooled with the throttle while I had someone else driving, adjusting timing mostly looking for idle settings. But I tried to set WOT max spark also, the motor will not run over 3000 rpm, starts choking, missing, loses power and fuel too rich it appears. That makes me think spark is too advanced, but it is max retarded. All of this makes me sit and stare off into space, and the only thing I can imagine now is that the flywheel has shifted a little, advancing timing a few degrees. I really hope that is the case. If it is a spline tooth that locks the flywheel in place that opens a different case of worms. If you can think of anything else, I have no problem checking it. I am willing and able to follow instructions, spent years trying to fix computers for people who said "Wait, do this! See? It doesn't work!" Thanks for your time.

 

[danalex]

Flywheel is off. There is a kind of wide area instead of a key that it indicates where the flywheel should line up. Doesn't look like anything is shifted. Not much of a lock in place deal, but none of the splines are broken so it has to sit in the correct place. I have a bare piece of wire on one of the coils, looks like an assembly bolt touches it. I'll see if it is grounding it. There are a few rub marks where the flywheel has spun, nothing major. No way to retard the timing more than I already have, the trigger hits support bolts and limits its travel. So. I'll check it with the ohmeter, if OK put it together or fix it if not. Fix the water pump and put that back together. Guess I will get a couple carbs. Air has to be leaking into the motor somewhere. Think I will pressure check it while the flywheel is off, make sure that top seal is ok. Only thing I can think of, something is leaking to vacuum while not leaking to pressure test.

Link and sync will not idle this motor down. If the spark controls the speed with the throttle closed (Idle), then the spark is advanced and I cannot physically retard it. The only remaining things it can be, as far as I can tell is 1. Leaking air, or 2. switchbox is faulty in such a way it advances timing.

 

[danalex]

Flywheel back on. Seems be same as before I took it off, started it up. Runs the same. New carbs it is. New to me anyway.