I’ve built a decent handful of motors over the years. Rarely have I done every part of the task, usually I’ve been part of a chain of people doing teardown, clean-up, machine work, re-assembly… This winter however, I had the pleasure of being involved in every phase of building not one, but two R6 race motors. One belonging to me, the other to my good pal Mike Doody with the welcome assistance of Midnight Oil’s most junior co-conspirator; Lucas Boyd.
Since both motors were being built in a garage and not a machine shop, Mike and I decided to tackle the builds in two phases. First we each went through our respective manuals and identified all the parts we knew we would need. This was done in preparation for Phase 1: Tear-down, clean-up, and rebuild until we got stuck. We planned to get stuck, it was a wise plan. There are several things that can result in stuckness: the need for machine work, unanticipated parts needed, general screw-ups… In the case of both motors, we did get stuck. I discovered that I could not complete my rebuild without a new trans output shaft, and Mike forgot to order new con rod bolts (which are one use only in the R6). Happily, we discovered that both engines were within spec in all the critical parameters so no professional machine shop services were needed. Once the second volley of parts were ordered and had arrived, we re-convened for Phase 2: another all-weekend attack that would be the final assembly. During phase two, I unfortunately discovered that my motor had a badly stretched cam chain, but we did complete Mike’s build.
Here are a few potentially useful things I learned during this undertaking. Some good, some bad…
We cleaned the engine parts in stages. First a rough clean in Varsol with stiff brushes to knock off the chunks, then a second clean with a fresh tub and fresh Varsol to get it to a decent state. Then we did a “dunk and swish” in a giant tub full of scalding hot water and Tide detergent followed by a rinse with equally scalding hot water, and a blow-dry with shop air. This worked great! The parts were generally not horrible to start with, but they came out looking like they had been hot-tanked. I highly recommend this method. It’s labour intensive but the results are great, and it’s containable within a home shop.
Torque-to-yield bolts are spooky AF. My motor, a 2003, has con rod nuts that are torqued to a modest starting point, then yielded 150 degrees! This was absolutely awful. We used a quality Snap-On angle meter, but it still wobbled and wiggled, which brought stress levels up to maximum. I also made the mistake of using a 3/8” to 1/4” adaptor (since the rod bolts are only 10mm). Part way though the yielding of the second bolt on the third cylinder, my adaptor snapped. I pooped. Full-on poo. Yielding a bolt already feels like a crime against nature, every fibre of your being crying out for you to stop, but then *BANG* right in the middle of it. It was a dreadful moment. You can avoid it by not using socket adaptors. Also, using a huge ratchet as extra leverage seems to help mask the fact that you are torturing that little fastener to an inhumane level.
Don’t use too much goop to seal the cases. I did. I put the smallest continuous bead of sealant that I could on the outboard edge of the mating surface between the upper and lower crankcase halves. I applied it with more care than a bomb technician or a painting restorer. This bead was like a single strand of perfectly formed vermicelli. It was too much. When I put the cases together and torqued everything down there was as big friggin’ udon noodle running the interior perimeter of my cases. Knowing that discretion is the better part of valour, and that an undisturbed hornet’s nest is best, I left it alone. Watch this space for a lengthy lament about clogged oil pick-up screens and blowed-up motors. Mike Doody, on the other hand, used his finger tip to smear only enough sealant that the mating surface took on a faint sheen. This was the right way to do it. When he bolted his cases together, it did not result in a long white Three Bond worm clinging to the crankcase seam.
Take breaks. It’s really easy to get brain fade when you’re focused on not missing any details and doing everything perfectly. When we were installing the cams in my motor, we could not get the cam timing right. It was near the end of the day and we just wanted to get it done so we ended up taking it back apart, doing something dumb, and then reassembling everything again. What’s that definition of insanity? Something about doing the same thing over and over and expecting different results? It was not until the next day, as I was pouring the milk into my morning tea that I realized the reason it wouldn’t time correctly was because the cam chain was stretched… A lot. Facepalm. The hours (literally hours) spent the previous evening trying to will the cams into phase was a complete waste.
Label everything. You can’t over do this. You know this, but here’s a practical way to do it: keep lots of parts bags around and every time you take apart a subsystem drop it into the bag and make a note right on the BAG! AMAZING! Then when the dirty crappy parts come out to get cleaned, transfer them into new bags, and re-write the notes! This act of physically writing something, and repeating it, and repeating it, will burn the note into even the mushiest of brains. That way when you pick up the oil pump you’ll remember that it has two dowel pins that go with it and which bolt holes they belong to!
Use the manual: but don’t trust it! The Yamaha manuals we were using both contained great booby traps. The section on the crankcase for Mike’s motor showed the final torque specifications of all the bolts, but not the fact that the final torque was meant to be approached in stages. For that little tidbit of information one had to refer to the list of key engine torques. A printed manual is nice because you can make little notes and records right there in the margins. I however, prefer a digital copy because I can Ctrl + F my way from cover to cover, making sure I read every sentence that contains those key words: “Crankcase bolt torque”.
This next tip is a good one: Newton meters are different from foot pounds (Haha Mike, you tool). But seriously, pay attention to your units. Most of my tools, having been bought in North America are in the US unit structure. The manual however, is sensible and written in modern units. It’s very easy to get turned around. My suggestion: pick a unit structure and stick with it. Convert everything as it moves from the manual to your torque wrench, micrometer, feeler gauge, or dial-bore gauge.
Plastigauge is for checking compliance not taking measurements, and this is fine. A plastigauge check is just that, a check. It will tell if you need to replace something, or if one-of-these-things-is-not-like-the-others, but it does not generate a deterministic result. You will know your clearances are okay (or not) but you will not know exactly what your clearances are. Ultimately we are taking these measurements to determine if parts are still suitable for service. If you really need to know exactly what the clearances are, then be prepared to invest considerably in expensive measuring tools; or take your bits and pieces to a machine shop that already owns these tools and knows how to use them.
My last helpful hint: Your caffeine and music consumption should be monitored carefully, and combined with consideration. Not enough double-double and you’ll be dragging ass. Too much and you’ll be pissing and jittery like an excited Cocker Spaniel. Music choice is similarly important (unless you’re one of those psychopaths who works in a totally quiet shop.) Doody and I found that “1000 Mods” and the associated Spotify radio channel was pretty much perfect, unless you’re using the micrometer. That calls for something more… measured? I recommend Steely Dan for precision measurement. You might not like it, but dammit, it’s being done properly!