Casey Simmons wrote:
G'day all,
I'm having some problems adjusting up the synchronisation etc of my 1971
60HP Johnson.I've purchased a SELOC repair manual, only to find the
information isn't as detailed as i'd have liked. As a result, i'm struggling
to get it to idle and run nicely. Any ideas on where to find the best
information and procedure for doing a full adjust up. Everything seems miles
out.

Thanks
Casey
South Australia



Sorry Casey I thought someone would at least try to help unless a dealer
saying you should buy a dealer manual is "help":-) it doesn't help them
that's for su-)

Below is assuming you can get some info from your manual, once you can
understand the basic principles of how it operates & the rationale
behind it, the existing manual will make more sense.

(i) It's a pretty old engine & always a tune is a good idea but don't be
too disappointed if despite your TLC it doesn't run like new. Lots of
things go away in two stokes, the crankshaft seals are not as tight, the
reed valves don't snap shut & the usual piston/rings & bore wear, the
throttle spindles leak air, etc etc, all play their little part.

(ii) Try to check the compression, ignition OFF, plugs out, wide open
throttle (WOT) & crank it with any of the elcheapo compression testers.
The actual numbers are not so important (again it's an old engine) but
each cyl should be reasonably close to the other (within 10% of each other)

(iii) The best thing to do is have someone work the throttle
very slowly back & forth (engine off) as you just watch what
happens with all the linkages, till you are familiar with it & the
various adjustment bits involved, what you should see is;
(a) At dead idle, the engine speed is totally controlled
by spark timing the throttles have been on their stops long before the
engine slows to idle. This is how they get a soft slow idle from a crude
2 stroke. There is no specified setting for the spark timing at idle &
it's sometimes very retarded being well AFTER top dead centre (ATDC)
(b) As the throttle is slowly advanced you'll see; the
top of the "throttle arm" advances the spark timing (the big plate under
the flywheel) then after some movement, the "throttle cam" will come
into contact with the "cam roller" & JUST start to move the carb
throttle shaft(s) This is called the pickup point & your manual "might"
give you a spark timing spec for this it's usually a couple of degs
before TDC (BTDC) If it doesn't don't worry.
(c) Tell your assistant to stop there, you should see
that the "throttle cam embossed mark" is exactly in the centre of the
"cam roller" if so then that part of the 'synchronisation" is OK, get
your assistant to continue to slowly open the throttle.
(e) Now as the throttle is increased, the carbs are
starting to open, as the spark timing continues to advance till the
"throttle arm" can move no further because it's resting against the
"advance stop adjustment screw" this is WOT (Wide Open Throttle)
(f) With the air silencer off look in at the carb
plates, they should be fully open & the linkage shouldn't be trying
to over open them.

Do this slowly a few times & you'll see how all the little rods,
string & sealing wax play together to manage the spark timing & the
carb(s)' throttle plate opening. The basic idea is the throttles are not
opened till the engine is well up from idle, below that all engine speed
is controlled by retarding or advancing the spark timing, once the
throttles start to open after the "pickup point" (roller is on ramp)
they should continue to open as the spark timing advances till the
timing as against it's adjustable stop & the throttle plates are fully open.

(iv) The spark timing pointer; before you start timing etc,
particularly on an older motor you need to ensure it's actually
"pointing" to TDC. A bit of a fiddle I am sorry but this is worth it.
(a) Get an old spark plug & bash the porcelain & spark
tang out of it.
(b) Put a small bolt & nut in the resultant hole so
when put in the motor it will hang down a little into the chamber
(just a bit not too far)
(c) Put it in #1
(d) By HAND & slowly & carefully bring the piston up
till it touches the bolt then mark the flywheel level with the
pointer.
(e) Turn the engine back the other way till the piston
rests on the bolt & again mark the flywheel level with the pointer.
(f) TAKE THE PLUG OUT NOW!!! Catastrophic if you forget &
leave it there, then turn the engine over;-)
(g) Measure between your two marks, the flywheel's TDC
mark should be exactly midway between the marks, if it isn't then
the pointer has been banged, bent or buggered & is not accurate so,
(h) Bend to pointer so it points to true TDC. (which
way & how much is obvious when you are doing it) Recheck.
(J) You did take the butchered plug out..... didn't
you???

(v) Adjustments;
(a) The carbs throttle plates need to be all against
their stops at idle, so loosen whatever interconnects them & links
them to the "throttle cam" & ensure they all snap fully against
their stops. (even against their stops the system is designed to
still flow lots of air). Tighten the screw then by moving the "cam
roller" you should see all the carb plates move together,
if not do it again.
(b) The "throttle pickup" point should be checked
next, slowly move the "throttle cam" till it touches the "cam
roller" & the carb(s)' throttle plate spindles "just" start
to move. The "throttle cam mark" should be in the middle of the
"cam roller", if not loosen the "cam roller screw" &
adjust so the carb(s)' plates JUST start to move when the "throttle
cam mark" is in the centre of the "cam follower" (roller)
Tighten screw & recheck.
(c) The throttle cable should let the "idle adjustment
screw" rest against it's stop, if it's not just touching the stop as
the cable runs out of travel or the cable is left too slack, adjust
the cable at the bottom on the air silencer where the cables enter
the engine.
(d) The next thing is the spark timing, some engine's,
the manual specs a "throttle pickup" point spark timing, some don't.
Also if the engine has a decal or placard somewhere which gives spark
timing always use that over the manual etc.. If your engine specs a
"pickup point" spark timing you can do it now; put a timing light on #1,
start the engine & gently increase the revs (you'll need the warm-up
in neutral lever to get it off idle) till the linkages are in the
"throttle pickup' point, then check the spark timing. If it's not
correct, speed up or slow down till the timing light is reading the
specified advance, then turn the engine off without touching or
changing anything, you can now adjust the link between the "throttle
arm" & the "throttle cam" so the "throttle cam top mark" is in the
centre of the "cam follower" (roller) Tighten all, restart &
recheck "throttle pickup" point timing. CASEY: In your old engine
checking the pickup spark timing is probably going over the top a bit,
so just make sure the roller is aligned with the mark on the ramp.

(e) Next the WOT spark timing. Bring the engine up to WOT
& max spec revs in the water, be careful OR much much better & safer

courtesy of rec.boat's Tony Thomas;

"You don't need a test wheel to do this. Disconnect the throttle
linkage from the timing advance rod. At idle advance the timing by
hand and check. I have also had someone drive the boat and check it
on a calm day but the linkage method is safer."

If it's not correct, you can adjust it with the he "advance stop
adjustment screw" just under the
flywheel's starter ring gear.

(f) Engine off put the throttle to WOT & check the
carb(s)' throttle plates are fully open & the linkage is not trying
to over open them, adjust if needed.
(g) In the water you can then set the idle speed with
the "idle speed adjustment screw". Get it as slow as is comfortable
for a nice shift which doesn't "clunk" too hard.

Good luck.

K