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Discussion Starter · #1 · (Edited)
<--Part 2b
Part 3b-->

'continued from Part 2b

If you have been following Part 1 & Part 2, your motor crankshaft is already in position for removing and reinstalling the cams.

Essential Knowledge

Refer to the third row in the Crank Chart "Crank Rotation Degrees 360" - this is the position for cam removal and installation (cylinder #1 TDC Exhaust Stroke).


If the crankshaft has not been turned since the cams were removed, a check of the rotor flywheel timing marks will be in alignment, exactly as they were set before the cams were removed - aligned properly and with cylinder #1 TDC Exhaust Stroke (RED timing mark added for clarity).

Glasses Vision care Eye Eyewear Font

Sketches are views from the "RIGHT" side of bike (foot brake side). Putting the motor in time, is a sequence of steps starting at the crank cam sprocket and working counter-clockwise to remove cam chain slack and align timing marks on the cams, and the final step of installing the cam chain tensioner and adjusting to remove remaining slack. In these sketches, the RED color indicates where the cam chain slack has been removed during reassembly.


Keep a clear understanding that when viewed from the "RIGHT" side of the bike (foot brake side), the running engine will turn clockwise. The crank cam sprocket turning clockwise will pull "down" so to speak on the exhaust cam and in turn pull the intake cam sprocket, the cam lobes opening and closing valves in time with the crank motion of the pistons without self-destructing. Before the valve cover goes back on, it is easy to confirm the motor is in time by simply checking the involved timing marks, rotating the crank one full 4 stroke cycle (720 degrees) and checking them all again. And then check them again, and take pictures to send to anybody who cares, that you do your own valves. It is also obvious if the motor has not been put in time. If the cam sprocket timing marks are off by even one tooth, it is visually impossible to ignore. The most dangerous thing (imo) is not mistiming the cams, it's dropping something "hard" into the motor.


The 4 sketches above result with the drawing below, where the final step of setting the cam chain tensioner is complete. This is a motor in time, and if any of your timing marks are not aligned with the engine case as shown below - no harm done, other than you get to go backwards removing the cam(s) to get to the step where the first misalignment occurred.



SEE THE YAMAHA SERVICE MANUAL. Use assembly lube on the cylinder head journals (where the camshaft "sits" when operating), the valve buckets, the cams, cam caps - all the "metal to metal" contact surfaces where movement occurs. What does not get assembly lube can be wetted with engine oil. Refer to Yamaha documentation. WET THE CAM CAP BOLTS because the torque specification is intended for bolts that have been lubed on the bolt threads with engine oil.

Position key tools within reach, and set both the cams on top of the cylinder head but back out of the way of the chain until they are needed (do not place them in final position). You want everything lubed and ready to go because you will be maintaining mild tension on the cam chain (starting with the chain between the crank cam chain sprocket and the exhaust cam).

My disorganized organization - as long as your brain knows what is what, you're good.


Pick up the cam chain with both hands, like a necklace. Shake the cam chain a bit, and it will "free up" a little more chain that may have been caught on some of the cam chain guides (important, even if you kept the chain on the cam sprocket, there still can be some chain entangled with the chain tensioner guides). Raise the chain, and you will feel it when it slides back on the crank sprocket, its a very secure fit. Don't try to muscle the chain, if you pull hard-hard you might turn the crank that is aligned for reassembly. You just keep a relatively small amount of tension on the chain. That results in a cam chain back on the cam chain crank sprocket (in RED).


Most of us only have two hands, so if you're not a squid lets tie up some of that chain so it's less likely to slide off the crank sprocket. Leave enough chain free to work on the next step, setting & timing of the exhaust cam. Below shows the extra slack taken up by a zip tie, and the right hand is holding enough of the cam chain to keep it on the crank cam sprocket.


Always while working to set the cams, be conscious of keeping some mild tension on the cam chain. It's not like it has to be tensioned every moment - I often let some slack into the cam chain while working on cams but by keeping it moderate, the cam chain stays on the crank cam sprocket.

Next step, set the exhaust cam. First take a clear look at the exhaust cam and it's timing marks out of the bike. There a two timing marks, one at "12" and the other at "6".


They will be aligned with the top of the engine case like below when the cam is set in it's journals where it rotates.


And when positioning the exhaust cam, because it has two timing marks - ensure proper position of the cam by checking the view from the "LEFT" side of bike (gear shift side) cylinder #1 cam lobes "FACE EACH OTHER". Below is a picture of both the cams, facing each other, as they are when in proper position for removal and installation of the cams. Align the timing cam marks, and make sure the exhaust cam lobes on cylinder #1 are oriented to "FACE EACH OTHER".


Let's begin the install & timing of the exhaust cam. We want to find the cam chain "rivet" (I will call it the "pin") that is in alignment with the top of the engine case, where the exhaust cam is positioned. I'm holding the chain (with the slack removed) as if it was wrapping around the exhaust cam gear, and that identifies the pin with the RED arrow as our target for cam alignment (the picture is taken from above and that distorts the view somewhat).


Let's use a diagram to show it at the top of the engine case "eye level". The chain is coming off of the crank cam sprocket and is snug with no slack, and the RED pin identifies where the exhaust cam timing mark needs to point (it should point just above the top of the pin just like the engine case does).


OK, so without losing track of the RED pin or creating any slack in the chain, hold the cam above where it will eventually sit and take the cam chain (with slack removed) and wrap it around the exhaust cam sprocket, with the timing marks on the exhaust cam pointing at the top of the RED pin like below. (Sorry, I can't draw "gear teeth", so the gear below is just the circle with the two timing marks.)

TIP: I have heard you can use "white out" from office supplies, and put a small dab of white on the pin - and wipe if off once complete. You can also use "mechanics pen" (Forney White Paint Marker #70818) that is oil based - but my old eyes can't see it very well.


And without letting the chain go slack (as you lower the cam down into the journals you must rotate it counter-clockwise to keep the cam chain tensioned with no slack), set the cam into it's journal seats where it belongs in the cylinder head, with the timing chain wrapped around it, without any chain slack between the crank cam sprocket and the exhaust cam gear.

See what we did ? - we used the cam chain off the crank cam sprocket to "measure" where the exhaust cam timing mark needed to be relative to the cam chain, then put the exhaust cam into the cam chain at that position.


The cam timing mark may be a little "high" (slightly above the engine case) because it needs it's cam cap bar to "seat" itself down a little further into it's journals properly. Take the lubed up exhaust cap bar (and read the Service Manual how to lube the cap bar bolts before inserting) and start the cam cap bolts in by hand. As described in the service manual, tighten down the exhaust cam cap bolts a small amount at a time, working from the outside to the inside, in a crisscross manner. ONLY FIRMLY SNUG THE EXHAUST CAM CAP BOLTS -you want them secure so things don't move but don't put any serious torque on the cam cap yet.


With the exhaust cam set in the head, the cam is both timed properly and it has no slack (indicated by the RED outline on the cam chain) below.


Continue with Part 3b
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