Raven's Roads
Living an interesting life: the travels and musings
of motorcycling author Linda R. Moore

This post is part of a series. The index is here. Aieee! There was a sharp POP as we were torqueing one of the left sidecover bolts - the bolt immediately became finger-loose, and could now be pulled completely out of its hole without rotating it. We found half of the case threads that had - up to now - been a permanent part of the case were now wrapped around the end of the bolt. This bolt was too short: it was only long enough to mesh with about half of the crankcase threads, so torqueing this bolt to the value given in the manual applied twice as much tension against the threads as intended. All three bolts holding the bottom of the sidecover were too short. As we reused the same bolts that were removed, it’s unclear when these short bolts were originally installed. We’ll try this new “instant thread” stuff - sure hope it works! Other solutions considered included drilling the remaining threads out, filling with liquid aluminum, J-B Weld, and tapping new threads - or just drilling and helicoiling. We’ll follow the directions included with the “instant thread” stuff. First, we’ll clean the bolt with some starting fluid, and dry thoroughly. Then, we’ll apply anti-stick to the bolt threads - no doubt an important step. ;-) It’s a pleasing blue colour. Now that we have a bolt ready to go, we’ll mix equal parts epoxy and hardener together apply it around the inside of the hole where we want new threads carefully [sorta] screw a bolt all the way into this glop (hey - this stuff starts hardening in tens of seconds!) …and wait for five minutes. After five minutes, we removed the bolt, and used a knife to trim the excess epoxy material flush with the case mating surface. The bolt squeeeked while being removed, and required about half of the torque listed in the shop manual. The threads look good - of course, any threads would look good at this point. We waited overnight before retorqueing with a different bolt. We had to add a moderate amount of torque while threading the bolt into the new hole, even though it was lightly oiled. It *did* torque to spec. So far, so good. I’m not (yet?) comfortable using this stuff on something structurally important, though. We replaced three of the original, shorter hex bolts (left) with longer bolts (right) from our parts box; these replacements happen to be Honda bolts. We verified that the longer bolts could be threaded into our sidecase a little bit further than they could reach with the sidecover installed. This is important, because a bolt that’s too long won’t hold the sidecover tight, and may even crack our sidecase when it runs out of threads. The appropriate tool bits, a hex bit and hex socket, are shown below. Two of the three new bolts are installed, with a hex-key-style bolt in the middle for comparison. Manufacturers use several kinds of fasteners for stuff like sidecovers. Phillips screws The head of a phillips screw is easily stripped when twisting hard. One has to use the proper-size, good-quality screwdriver, and push while turning. The phillips screwhead usually strips before the case threads. A phillips impact driver can usually loosen stubborn screws, but is generally too large and heavy to carry in a portable motorcycle tool kit. If a phillips screwhead is stripped, it may be necessary to drill off the screwhead, remove the sidecover, and use a visegrip to remove the exposed screw threads. conventional bolts Most bolts can be accessed with a wrench, but difficult-to-access bolts may require a socket. Sockets are heavier and more bulky than allen (hex-key) wrenches - they don’t travel well in a motorcycle tool kit. Large amounts of torque can be easily applied - enough to easily strip case threads if one overtorques. hex-key bolts Easiest to access - generally. Large amounts of torque can be applied - enough to strip case threads if one over-torques. L-shaped allen (hex-key) wrenches are light and small - they’re easy to carry in a motorcycle tool kit. Allen (hex-key) socket-drive bits are available for torque wrenches. Many people replace manufacturer-supplied phillips case screws with aftermarket allen (hex-key) bolts for these reasons. (EBay is one source.) Let’s finish up the sidecover. We’ve smeared grease in the general direction of the solenoid lever. ;-) (If one cup of bleach is good, two cups must be twice as good. NOT. ;-) The solenoid is to the left; the torx bolt on the right is fastened to the starter fork shaft inside the sidecover. The underside of the solenoid cover is in the middle. The old black gasket is to the left; the new grey gasket is to the right. Uh-oh. The new gasket’s lower bolt hole doesn’t match our cover. We’ll reuse the old gasket on the left, as it’s in fair condition, and this isn’t a critical item. The left sidecover and solenoid cover are installed and torqued. The timing window is visible (about 11 o’clock from the crankshaft). the crankshaft nut is visible through its hole in the center of the sidecover. Next, we’ll install the cover over the crankshaft nut. This cover seals the access hole in the left sidecover for the crankshaft nut. This part sure resembles an old Honda 305 valve tappet cover. The black O-ring keeps oil away from the decorative cover. Three phillips screws hold the decorative gold-and-silver cover on the sidecase, hiding the timing window and crankshaft end cover. We’ve temporarily installed the clutch cover. Because this cover must be removed when we finally attach the clutch cable, the two bolts are only finger-tight. This post is part of a series. The index is here.

This post is part of a series. The index is here.

We’re ready to install the left side cover.

The two crankshaft position sensors (pictured about 11 o’clock and 2 o’clock) sit outside the flywheel.

They signal when to fire each spark plug.

The 18 alternator stator coils (pictured below the two position sensors) are positioned inside the middle of the flywheel/rotor. The alternator rotor includes 6 permanent magnets (6 north poles, and 6 south poles).

As the alternator rotor spins, each of the 12 (north/south) permanent magnet poles generates an alternating (positive/negative) current in the coils.(A changing magnetic field moves electrons in a conductor.)

The alternating current is rectified (by 6 diodes - also known as rectifiers) and voltage-regulated (to about 14.5 volts) in the rectifier/regulator assembly (located behind the left passenger foot peg), to keep the battery charged.

Here’s a better view of one of the ignition (timing) pickup coils.

Wires to the alternator stator and crankshaft position sensors travel through this rubber plug.

These three alternator stator wires (seal bottom) and ignition pickup wires (seal right) exit the engine (seal top-left) through this rubber plug.

The 18 alternator stator coils are wired in a (series? parallel? both?) ‘Y’ configuration, with six coils per each of the three legs of the ‘Y’, so only three wires connect the stator coil assembly to its rectifier/regulator assembly (located behind the left passenger foot peg).

Each of the three stator wires goes to a pair of diodes: one diode’s cathode and another diode’s anode. The remaining six anodes are connected to the battery’s negative terminal, while the remaining six cathodes go to the battery’s positive terminal, perhaps through the voltage regulator.

If the engine is run with a weak or disconnected battery, one or more of the six diodes (rectifiers) in the rectifier/regulator assembly may fail.

It’s usually possible to substitute a full-wave rectifier in place of one or two pairs of failed diodes. Radio Shack sells a suitable full-wave (four-diode) rectifier for $5 - much cheaper than Yamaha - but that’s another story.

The clutch push rod thing is at the bottom left.

The clutch push rod mechanism.

When the clutch lever is applied, the plate and button are pushed towards the clutch by the internal worm threads. The button pushes against the long push rod, which pushes the short push rod, which pushes against the clutch basket cover, unclamping the clutch/friction disks, which disconnects the engine from the transmission.

The starter solenoid hangs off of the top front end of sidecover.

The large exposed stud with the nut (top right) will be connected to the battery.

The smaller push-on terminal (top) will be connected to to the starter button.

The large black cable will be connected to the start motor. (Poor picture - sorry.)

The starter motor shaft hole is at 7 o’clock, and the starter fork shaft hole is at 8 o’clock, with respect to the solenoid.

The large metal/rubber/metal bushing for the starter gear shaft is at the extreme lower-left.

We’re ready to install the left sidecover gasket.

The left sidecover gasket is being held in place by its two locating dowels and a thin film of oil.

We’ve added the left sidecover and its bolts.

Since these bolt lengths vary, we’ll first match the bolts to the appropriate holes by checking their exposed lengths.

We’ll finger-tighten the bolts before torqueing ‘em.

The starter fork shaft bolt is torqued to its rod; this bolt has a torx head.

Yeah, we might have overdone it with the water-resistant white grease. ;-)

The shifter shaft is at the top right.

The shift pattern (1-N-2-3-4-5) is in the middle.

The oil level window is to the left.

This post is part of a series. The index is here.

This post is part of a series. The index is here.

We’re ready to install the right-hand side cover.

We’ve oiled the mating surface between the new gasket and crankcase to facilitate later removal, if necessary

The cylindrical oil filter compartment is at the lower right.

The crankshaft oil nipple is between the clutch and timing gear.

The right side cover.

The shiny round bump gives the clutch a little more room.

The oil filter opening is at the lower-right.

The inside view of the right side cover.

The clutch lives in the large round area to the right.

An oil gallery feeds filtered oil from the oil filter opening (bottom left) to both the crankshaft oil collar and to the crankcase oil passage that eventually supplies filtered oil to the camshafts.

The hole on the end of the crankshaft feeds filtered oil to the big ends of the rod bearings.

The oil passage between the oil filter, crankshaft and oil pipes is visible.

Filtered oil from the side of the oil filter opening is fed to the crankshaft oil feed (image center) and, via the right case half and external oil pipes, to the camshafts.

The oil filter cover.

The filtered oil enters the large round hole in the center of the cover, and exits via the smaller hole on its side.

This end of the oil filter faces towards the oil filter cover.

Normally, pressurized oil from the oil pump passes through this paper filter element to the filter interior, then exits the filter through this (big) hole into the cover, and eventually lubricates the big-end rod bearings and heads In many areas of life, there seems to be a couple of mostly-harmless-appearing actions that can have grave consequences down the road: this is one of them.

The oil filter will physically go in either way.

If the filter is installed backwards, the oil filter cover won’t go on quite as far by hand, and one has to wrench harder on the cover bolts.

If the engine is run in this condition, a bad thing happens: no oil is fed to the rod bearings or heads.

To compound this potential problem, these engines do not have an oil pressure sensor - they have an oil level sensor instead. The red oil level idiot light will not warn you if the rods and head aren’t receiving any oil This scares my chickens.

This end of the oil filter faces towards the middle of the engine.

The small opening to the oil filter bypass valve (surrounded by the black O-ring) is visible If the oil filter element becomes really clogged, pressurized oil goes in this end of filter, past the small spring-loaded oil filter bypass valve (visible), and exits at the other end of the filter, without being filtered.

We’ve put the right side cover on, and have threaded the bolts in just one turn so we can check for the appropriate bolt length.

All the bolts should extend about the same length from the side cover.

If some bolts are significantly longer and/or shorter than others, we don’t have the correct bolts in the appropriate holes.

A bolt that’s too short may strip its threads when it’s torqued; a bolt that’s too long may not hold the side cover tight, may strip its threads, or may crack the case half.

All the bolts appear the correct length, so we’ll evenly torque the side cover.

There are a lot of bolts.

A view into the oil filter compartment with the side cover attached.

The oil inlet and oil outlet galleries are visible.

Oil under pressure enters the oil filter compartment (about 4 o’clock; only partially visible), surrounding the outside of the filter element Oil is filtered as it travels through the filter into the cartridge interior Filtered oil travels out the big end of the cartridge, through the cover’s oil passage, exiting through the oil journal near the top center of the picture.

Because dirty oil is trapped outside the filter, it’s a good idea to clean this compartment during oil changes.

The three raised pads at the bottom of the compartment allow oil to get to the oil filter’s built-in pressure relief valve.

The O-ring around the bottom bolt hole probably allows any pressurized oil that’s seeped past the oil filter cover gasket to return to the crankcase, rather than seeping outside the case.

The oil filter has been inserted in the correct direction.

The large opening in the filter faces out, towards the oil filter cover.

Filtered oil travels out of this opening, through the oil filter cover and sidecase, to feed the big-end rod bearings and camshafts.

This post is part of a series. The index is here.

This post is part of a series. The index is here.

Now that the front head is installed, we can time the front camshaft.

The rear valve train is already timed, so we must time the front cylinder to both the crankshaft and to the rear camshaft.

We’ll use a wrench to rotate the engine from the left side.

If there’s too much slack in the cam chain, the cam chain will wrap around its lower sprocket and jam as the crankshaft is rotated, so we have to hold it up.

It’s simpler to loop the chain around a round socket than to try to hold the top of a moving chain.

The crankshaft is now at the rear (#1) cylinder’s timing mark, denoted by the ‘T’.

The rear (number one) camshaft is within one sprocket of its timing mark. This sprocket is pulled counterclockwise (as viewed here) one-half turn for each full turn of the crankshaft: the camshaft timing dot is nearest its timing mark in this position.

The camshaft timing dot hasn’t quite met its case mark, so it’s a little retarded: this is expected with a used chain. (Used chains are slightly longer.)

Starting from the rear (#1) cylinder’s timing mark, we’re advancing the crankshaft 285 degrees (about three-quarters of a turn) clockwise, as viewed from this side) to stop at the *front* (#2) cylinder’s timing mark. If we had turned the crankshaft *backwards*, we’d only have to move the crankshaft 75 degrees - but that would be opposite the normal direction of rotation. (The two cylinders are physically oriented 75 degrees apart on the crankcase.) (360 - 75 = 285 degrees)

(The crankshaft normally rotates clockwise when viewed from the left-hand side of the engine, and counter-clockwise when viewed from the right-hand side.)

We’ve stopped at the front (#2) cylinder’s timing mark, an unlabeled line.

This is a view of the rear (#1) camshaft when the engine is timed to the front (#2) camshaft’s timing mark. The rear camshaft has advanced (counter-clockwise) about three-eighths of a turn (142.5 degrees). (The camshaft rotation of 142.5 degrees corresponds with a crankshaft rotation of 285 degrees: 285 / 2 = 142.5)

The camshaft makes one rotation for every two rotations of the crankshaft. So, there are actually two rear camshaft positions that correspond with the front cylinder’s crankshaft timing mark:

• A rear camshaft position of 142.5 degrees
• A rear camshaft position of 322.5 degrees
  • This is a half-turn additional difference.

  • (142.5 + 180 = 322.5 degrees)

Of these two camshaft positions, only the one that yields the larger cam degree difference between the front and rear camshafts is correct for this Yamaha engine.

(Generally, the larger the difference, the smoother the engine runs; the smaller the difference, the lumpier the engine runs.)

• rear cam at 142.5 camshaft degrees:
  • front cam at 0 degrees

  • difference between camshafts is 142.5 camshaft degrees
  • This is the larger difference between camshafts.
  • This is the correct timing setting.
• rear cam at 322.5 camshaft degrees:
  • front cam at 0 degrees

  • difference between camshafts is 37.5 camshaft degrees
  • (360 - 322.5 = 37.5 degrees)
  • This is the smaller difference between camshafts.

The crankshaft is still at the front cylinder’s timing mark, an unlabeled line. The rear cylinder’s timing mark, a ‘T’, is about 9 o’clock; the front cylinder’s timing mark, a single line, is about 11 o’clock.

The timing gear dots for the front cylinder align. Cool.

To check the front (#2) camshaft’s timing mark, we’ll take the slack out of the chain on the *tensioner* (left) side of the chain, just as the cam chain tensioner would do. Since this sprocket is pulled clockwise by its chain, the sprocket mark is slightly *retarded* (with respect to the case timing mark): this is expected with a used chain.

The front cylinder’s rear cam chain guide, viewed from the tensioner hole.

The chain slack can also be removed by pushing on the guide with a finger.

The front camshaft timing looks good. We’re applying finger pressure on the left-hand cam guide (not visible) to keep the chain taut. Because the sprocket timing mark hasn’t quite reached the head timing mark, the camshaft is slightly retarded (not advanced).
When the engine’s running, the front cylinder’s sprocket is pulled clockwise (chains can’t push ;-).

We’ll add the front camshaft’s oil slinger, washer and bolt. It’s necessary to hold the oil slinger dimple (just above the bolt) positioned over the corresponding hole on the sprocket until the bolt is finger-tight.

We’ll prevent the alternator from moving (by holding it) while torquing the front camshaft bolt. Because the cam chain tensioner isn’t yet installed, the camshaft tends to turn a bit clockwise as the left chain loop became taut.

Before we can attach the cam chain tensioner to the cylinder, we must “wind it up” to retract the tensioner plunger into the body.

The plunger retracts into the tensioner body as we tighten the screw while simultaneously pushing down on the body.

The tensioner plunger is almost completely inside of the tensioner body after being wound up. It’s ready to be installed with a new gasket.

We’d like the tensioner gasket to stay intact if it ever has to be removed in the future, so we’ll apply a thin coat of oil to the mating surface.

We’ll also lubricate the tensioner bolts by dipping the threads in a capful of oil.

The tensioner is held in position by two bolts.

A slight push on the screw head activates the cam chain tensioner.

This little dust cover snapped into its hole over the adjustment screw with a furm push. Sometimes it’s necessary to shove the edge of the rubber cover into its hole with a tiny screwdriver.

The cam chain tensioner is done.

Let’s do a front timing check. The front cylinder cam sprocket timing marks line up within one sprocket’s width. Since the front sprocket is pulled clockwise, the timing appears slightly retarded, which is typical of a used chain.

Front timing check (continued). The front cylinder timing gear dots on the right-hand side of the engine are aligned.

Front timing check (continued). The timing window on the left-hand side of the engine shows the *front* cylinder’s timing mark, an unlabeled line.

Front timing check (continued). The rear camshaft is about 142.5 camshaft degrees (285 crankshaft degrees) past its timing mark. (The *rear* sprocket is pulled counterclockwise (when viewed from this side).) The front timing appears correct.
Yes!

As long as we’re here, we’ll torque both of the starter motor bolts to the right-hand case half. We could have done this any time after torquing the case halves together. We’re just getting around to it.

A front view of the starter motor.

This post is part of a series. The index is here.

This post is part of a series. The index is here.

Now, we’ll time the front (#2 cylinder) timing gears.

We’ve already timed the rear (#1 cylinder) gears.

The front cylinder’s timing gears live behind the right-hand crankcase cover.

1. First, we rotated the engine so the driven (upper-right) timing gear mark faces the crankshaft (lower-left).
   (The crankshaft’s timing mark happens to already be aligned to its driven gear in this image.)

2. Next, we pinned the driven and anti-lash gears together through their common alignment holes with a round torx bit that happened to fit.

We can now remove the driven gear’s shaft and easily lift the driven gear, along with the pinned anti-lash gear, up and away from the crankshaft gear.

We’ll keep the gears separated by the weight of this screwdriver.

We can now rotate the crankshaft, along with the #1 (rear) camshaft, without moving the front timing gear.

We’ll use the timing window to more accurately set the crankshaft to its timing mark.

We have to remove the Yamaha emblem to see the timing window: it’s retained by three screws.

These screws wouldn’t budge with a screwdriver, so we used an impact wrench.

The impact wrench body is first twisted slightly (counter-clockwise for loosening) against the tool’s internal spring pressure. The screw loosens when the end of the impact wrench is hit with a hammer.

We can now see the timing window (at the upper left).

The round crankshaft-end cover in the middle of the sidecover provides access to the crankshaft bolt.

This cover bears a striking resemblance to a Honda 305 valve tappet cover.

The timing pointer is visible behind the plastic timing window.

We’ll want to watch the timing window while rotating the crankshaft, so we’ve also removed the crankshaft-end access cover.

The arrow above the crankshaft access hole shows the normal direction of rotation of the crankshaft (this is the left side - it rotates clockwise).

Another way of remembering which way the crankshaft spins: if the bottom of the spinning crankshaft could touch the ground, the crankshaft would move towards the *rear* of the motorcycle.

Also, the camshafts spin in the *opposite* direction of the crankshaft.

Here’s the inside of the left sidecase cover.

The timing window resides between the two crankshaft position sensors (under the curved metal bracket) and the alternator stator coils.

The crankshaft position sensors sense the holes drilled in the side of the alternator rotor as the rotor turns, and command the ignition modules to generate a spark.

Because there is no camshaft position sensor, each coil provides a spark just before TDC (top dead center) at both the end of the compression and the exhaust strokes, but only the former is useful.

The timing pointer resides at the very top of the window.

We’ll use the #1 cylinder’s timing to time the #2 cylinder. This is the #1 cylinder’s camshaft sprocket, at the engine’s left rear.

We rotate the camshaft in its normal direction of rotation, counter-clockwise, by moving the bolt on the left-hand end of the crankshaft clockwise.

The timing dot on the sprocket is within a half-tooth of its case timing mark.

We’ve temporarily installed the left engine cover so we can more accurately set the crankshaft timing.

The marked edge of the alternator rotor is visible through the window.

While looking through the timing mark window (on the left side), we rotated the crankshaft to the ‘T’ (timing) mark.

There are only three timing marks that we might view through this window:

1. ‘T’ (timing) marks TDC (top dead center) for the #1 (rear) cylinder (shown).
2. ‘|’ (a single line) means TDC for the #2 (front) cylinder.
3. ‘F’ (fire) denotes the firing range for the #1 (rear) cylinder.

We can grok what’s going on a lot easier by just making our own pointer out of a paper clip.

As the alternator/flywheel is turned clockwise (as viewed from this side):

1. The plain-line (#2 cyl TDC) mark passed the pointer first.
2. The ‘F’ (#1 cyl fire) mark passed the pointer next.
3. Our homemade pointer is now at the ‘T’ mark (#1 cyl TDC).

We’re (still) at the ‘T’ (#1 cyl TDC) mark.

This is the #2 (front) piston.

1. The #1 (rear) piston is at TDC.
2. The #2 (front) piston (shown) has already passed TDC, and is on its way down.

We’ve continued to turn the crankshaft until the front piston (shown) reached BDC (bottom dead center).

(The front piston is still at BDC.)

This rear camshaft is at about 52 cam degrees, more than halfway through its power stroke. (The camshaft turns counterclockwise.)

(The front piston is still at BDC.)

We can also verify that the front piston is at BDC because the crankshaft timing dot is furthest away from the front timing gear.

The crankshaft is turned (clockwise) to the #2 (front) cylinder’s timing mark (the single line near the top of this image).

The front piston is now at TDC.

(Unfortunately, the timing mark pointer is not quite visible. Darn.)

The front piston is at TDC (shown).

(The front piston is still at TDC.)

This rear camshaft is at about 142 cam degrees, more than halfway through its exhaust stroke. (This critter turns counter-clockwise.)

The front piston is at TDC, at the start of its power stroke, the timing window shows a single line (the front cyl timing mark). and the front camshaft should now be set at its timing mark.

The front timing gears’ dots are now aligned,and we’ve allowed the front driven (upper) gear to drop down, meshing with its driving (lower) gear.

The front timing gear shaft is reinserted - with its oil catcher facing up - so oil will lubricate the driven gear.

The front timing gear shaft retainer is installed and torqued.

We’re done timing the front timing gear.

Just for fun, we’ll turn the crankshaft some more while noting the rear camshaft, front piston, and crankshaft timing marks.

When we’re done taking pictures, we’ll turn the crankshaft backwards to where it is now, so the timing dots again line up.

We’ve turned the crankshaft until the timing window again shows ‘T’ (the rear piston is again at TDC), but this time the rear camshaft is at 180 cam degrees (shown), so the rear piston is now at the start of its intake stroke, not its power stroke.

• The (rear) piston is about to go down, sucking fuel/air into the cylinder.
• Both (rear cylinder) valves are slightly open.
  • The exhaust valve is almost closed.
  • The intake valve has already started to open.

This rear camshaft is now at about 232 cam degrees (shown), more than halfway into its intake stroke.

The front piston is at BDC, the start of its exhaust stroke.

The timing window shows a single line (#2 piston TDC).

This rear camshaft is pictured at about 322 cam degrees, more than halfway into its compression stroke.

The front piston is at TDC, the start of its intake stroke.

This post is part of a series. The index is here.

This post is part of a series. The index is here.

We did a quick check of the valves without removing them from the head.

We used a breaker bar on a deep socket to rotate the camshaft bolt to examine the seating surfaces.

The exhaust valve (left) opens as we rotate the camshaft nut.

The diameter of each valve is just a bit larger in diameter than the circular opening it covers when it’s closed. The head and valve have a similar bevel. We’re looking for a nice smooth, uniform ring where the head and valve seat together when closed.

A moderate amount of torque is required to overcome the valve spring pressure.

Exhaust valves tend to run hotter, and take on a lighter appearance, than the cooler-running intake valves.

Exhaust valves are typically smaller bigger than intake valves because the intake gas [the air/fuel mixture, not just gasoline) is sucked into the cylinder at a much lower gas pressure than the exhaust gas is expelled.

(Disclaimer: I am not an automotive engineer.)

The exhaust valve, from the side.

The valve’s sealing surface appears as a darker, beveled ring just below the top of the valve.

More efficient engines utilize two intake and exhaust valves per cylinder
to make it easier for the cylinders to ‘breathe’.

As we continue rotating the cam, the breaker bar is being pulled from our hands as the exhaust valve spring closes the valve.

The intake valve, from the side.

The valve’s seating surface is visible as a brighter, beveled ring just under the top of the valve.

We’ve cleaned the front cylinder’s mating surface where the head gasket and head will sit.

A new head gasket has been placed over the studs, cam chain and guides.

We’ll thread the cam chain into the head with this wire.

This is the front head. The exhaust port is to the right.

The camshafts in the two heads differ: according to the manual, the rear and front camshafts should be marked ‘1′ and ‘2′, respectively. Somewhere.

We’ve removed the bolt, washer and oil slinger so we can see the cam sprocket in the head.

The cam sprocket turns with a finger-touch over the section of its travel where both valves remain closed.

We’ve turned the camshaft counterclockwise as far as we can by hand.

As the camshaft is normally rotating clockwise [as viewed here), the intake valve has just closed, and the piston is beginning to compress the air/fuel mixture in the cylinder.

We’ve turned the camshaft clockwise as far as we can by hand; the exhaust valve would begin to open at this point.

We’ve removed the sprocket from the end of the camshaft so we have enough room to pull the cam chain up by its wire.

The front cam chain sprocket, oil slinger, washer and bolt.

We’re lowering the front head onto the head gasket and cylinder.

Some old, yucky plastic anti-noise head stud coating was apparently left behind in the head. The remains jammed between the studs and the head passages, and preventing the studs from being inserted all the way through the head.

We had to clean the head stud passages with a screwdriver before installing the head all the way.

Because one of the two dowels remained attached to the head, we had to reposition the head gasket onto this dowel manually as the head got close to the cylinder.

Both dowels are now touching both the head and cylinder.

The head is almost seated.

The head gasket is actually a three-part fiber/metal/fiber sandwich.

We lightly hammered on a piece of wood held against the top of the head to seat the head.

The fins tend to be brittle, so we avoided applying force around the outer edges of the top fin.

The head is effectively seated.

We’ll lubricate the threads on each stud with a little oil.

Next, we’ve added oiled washers.

Finally, we threaded the stud nuts up to their washers by hand.

We’re ready to torque the head.

First, the four head stud nuts are torqued in a criss-cross pattern.

Next, we oiled the underside of the cap nut and its threads before torqueing it.

Finally, we torqued the two head bolts.

The front head is finally torqued onto the engine.

Next, we’ll add the camshaft sprocket and time the front camshaft.

This is the right-side view.

The clutch lives on this side.

The front view.

The starter lives below the front exhaust port.

The alternator [image right) protrudes farther than the clutch (image left).

The left side view.

The alternator, gearshift and starter gears live on this side.

The rear view.

The U-joint is at the rear left.

The free end of the U-joint will mate with the driveshaft when the engine is reinstalled in the frame.

This post is part of a series. The index is here.