Cut 'em if you want to replace pushrods with adjustables
and not take the rocker boxes off.
I don't know why I think this is wild, but I do. There's
something so damn old school about this. In essence this allows
any builder to take all the electronic bullshit off his Twin Cam,
including the battery and make it a kick-start-only magneto
driven motorcycle. This Morris Magneto returns the latest
powerhouse to a one-wire off the alternator to the lights and
your done, chopper. I think that's bitchin and I'm dying to know
if Paul Yaffe has built one. He was the first Twin Cam Chopper
The only way to remove the stock, non-
adjustable pushrods is to remove the rockerbox covers, the
rocker blocks and the rocker arms, then take them out through
the top. They need to be replaced the same way.
Okay, here's the installation instructions from Dave Shaw,
the master of Morris Magnetos. We don't have all the photos we
need, but there's more help in the S&S Gear Set Installation here
on Bikernet, if you need additional info. This install also uses
S&S gear drives and cams when making this modification. Click here for S&S Gear Drive Install Tech
Let's get started:
Removed the cam cover, locked the tensioners back, pulled
the gears and prepared to remove the cam support plate.
It's a good notion to remove these four bolts,
holding the oil pump in place, first.
Once the case was removed from the engine,
Dave removed the cam chain tensioner.
This clip ring allows the cam to be press out without the
bearing, but usually they slip out together.
Bolting on the new S&S cam gears and cams in place. See
the Bikernet.com S&S gear drive installation tech. It's not a bad
idea to bolt it all in place then test for drag by spinning the
engine, before installing the mag.
Here is the Mag drive gear. Make sure it's
centered so that the mesh with the mag drive shaft is
Install Twin Cam gear set per supplier’s instructions,
substituting the cam gear bolt with parts supplied: magneto
drive gear, spacer, and bolt. Gear should run concentric within
.001” t.i.r. upon final tightening, so it will be necessary to
mount a dial indicator; apply a small amount of red Loctite to
the gear mating surface and bolt threads.
A light film of oil
between gear and washer may help to align and seat bolt
properly. Finally tighten to 45 ft/lbs.
Using a 12-point 1½” socket, remove drive shaft assembly from
cam cover, being careful to not loose any shim washer(s).
Tighten bolt in steps, tapping on base of drive gear assembly to
achieve concentricity while turning cam.
Dave indicated where the Morris Mag drive shaft met with
the Mag drive gear. Shift the body around until there's virtually
no binding and not much gear lash.
NOTE: Be sure to keep socket straight to
prevent damaging drive top.
Checking for gear lash.
Place cover on engine, and shift cover around while looking
in bolt-holes to insure that there is enough clearance between
cover and cam plate. Mount cover with gasket, and hand tighten
bolts provided. Now thread the drive shaft assembly back into
cover, from the top (should thread in freely by hand, do not
cross-thread) to about 40 ft/lbs. Gear lash must be set by
shifting cover; location is proper when gears are free, and any
lash is barely noticeable. Rotate cam gear to check lash in
different positions. Lock down cover mounting screws securely.
This shot demonstrates how the mag is lubricated. The oil
comes into the mag cavity (slot) and the round hole allows it to
lubricate the drive shaft and gear.
Remove drive shaft
Set your engine on the correct stroke & position for installation,
a) Remove your rear spark plug only; you will
be using rear cylinder for piston position only.
engine until you feel front cylinder compression; rear piston will
be on the way up.
c) Continue turning the motor until
the rear piston gets to the top. This is 45° before front cylinder
TDC, a good starting point from which to set timing. We have
achieved best results with a timing of 35 to 37 degrees BTC, so
you will need to rotate engine about 10 degrees further; this can
be done by using a degree wheel, checking piston position, or
accessing the flywheel notches thru the stock pickup port (11.25
degrees per ‘tooth’).
Note: Due to whatever combination of
components and modifications have been performed, you may
need to change your timing spec.
This shows the various position the mag studs can be
placed for proper timing and alignment. It also shows the exact
point mag timing position.
Remove magneto cap. Set magneto rotor so narrow cam
lobe is located counter-clockwise from cam follower as in
Picture 2, and breaker points are just opening. This is your
correct front cylinder advanced timing position. On the bottom
of the magneto, note position of drive lugs in relation to
Here's the key to the mag and can be adjusted to fit the mag
position by lifting, turning the drive shaft and returning it to
Install the drive shaft assembly so that either pair of slots
on drive is in a similar position in relation to hold-down stud
holes; this way, slots will line up and engage lugs when
installing mag head, with both the engine and mag head in
firing position. Slot position can be changed in 18 degree
Note that there are two sets of holes in which
you can install the studs; choose whichever pair lines up best for
mounting mag head in the position you want.
Once all the lash adjustments are made and the position of
the mag correctly determined the mag drive shaft can be
Using a drop of blue loctite, securely install studs by using
two nuts jammed together. Tighten drive shaft assembly 80-100
ft/lbs with threads lightly oiled. Grease gears liberally, install
side plate and gasket.
Install the magneto and gasket, securing
with the nuts and heavy washers provided. If you wish, you can
check for 'points open' by using a good digital ohmmeter;
reading will increase by about .3 ohms.
Re-install cap (make sure coil springs line up), and tighten
so gasket does not compress more than 25%. Stud on side of
magneto is used to "kill" magneto with a grounding toggle
switch or lever (p/n KSL).
Do not connect to your 12-volt system!
Here's a side tip. Dave feels that compensating
sprockets are useless and harmful to primary systems and
starter motors. He welds 'em up.
Stuff to know:
This magneto was designed to start
with a moderate kick. Hard kicks may actually hamper starting.
Unit is also fully compatable with electric start, however, due to
weak gears in the electric start system, it is recommended that
you eliminate the compensating sprocket by replacing or
The long-lasting OEM-type points in your
magneto have been set at .015, and will require no attention for
years. When replacement is necessary, use Morris p/n P5 and
condensor p/n P6. Use only original type cap, gasket, points and
Initial spark plug gap .025. Due to the hot spark,
may burn larger faster than before. Use of a single-fire module,
Morris p/n MSF, may help prolong plug life. Use copper or
stainless steel solid core (non-suppression) spark plug wires
(Morris p/n MWS).
Gettin' ready to kick his Morris Mag powered racer.
Morris Magnetos mf'd under US Patents 4191157,
D375509, applicable pat's pend.