Next, you take out the cam chain tensioner (simple - see the manual) and top rub/retaining plate, and then you start unscrewing the cam caps. This is fiddly, since while 1 and 4 are at TDC, the valves on the other cylinders are in various stages of actuation, so there's pressure on the cam and valves. Patience is required. Progress is slow and methodical. Once everything's undone, the chain gets pulled off and the cam comes out. You remove one cam at a time, according to the Holy Book of Triumph. I removed the intake cam first, then exhaust. The cams, caps and bolts got laid out in the order they were removed. Here's the first one
When the cam out, you're facing this. With the bits out, the buckets and shims are easy to get to.
The buckets come out and the shims replaced one at a time. This is the top of the valve stem, shim removed.
Beneath each of those buckets is a little tiny shim, 7.48 mm in diameter. They tend to stay with their bucket when removed, thanks to the oil, but be careful - you don't want to drop one.
Earlier, all measurements were recorded on a worksheet, along with proper spec and difference. Did I mention this whole process is very fiddly? As each shim was removed, it was measured with a micrometer and noted (although the thickness is printed on them, the printing can wear, as can the shim). Maths were then performed to determine the correct thickness needed for the replacement shim.
Click here for a worksheet!
Basically take the difference between measured clearance and ideal clearance (I use the larger, looser end of spec as ideal, as the tendency is to tighten over time). Then, take size of old shim, subtract the difference from spec (since you want a larger gap, you're going to use a smaller shim) to get the ideal size of the new shim.
Old shim size - difference from ideal spec (ideal gap minus measured gap) = new shim size
or let's say you have an ideal gap of .15mm. Your measured clearance was .11mm. The difference is .4mm. Your old shim was a 2.6mm.
So 2.6mm - .4mm = 2.2mm for the new shim to achieve the desired gap.
On the worksheet, ideal replacement shim thickness was noted, as was the anticipated clearance when complete. Since all the math was done beforehand, it was just a matter of picking out the shim and putting it in, then putting on the bucket.
And so forth 16 times!
Now, factory shims come in smaller increments, but cost about $8 each, although some shops will swap shims with you for free. I haven't even been in a shop in years. So I got an aftermarket shim kit. It has shims in increments of .05mm, which probably isn't going to give you an exactly matching set of clearances, but you can get them within 1 or 2 thousandths. Yes, it's a compromise. No, you're not building a MotoGP motor. Get over it. Or spend 8 bucks a shim.
Now came time for reassembly. Although I had pictures of everything, I was a bit perplexed as to whether the 1 and 4 pistons were actually at TDC where they were supposed to be. The Holy Book of Triumph showed pictures of the crank indicator level and even with the seam between the case and cylinder. But mine clearly was not. I needed to make sure I was at TDC before putting the cams back in.
You will notice a hole above the crank where you can see the actual rod, complete with "Triumph" logo embossed. That's one way to check for TDC (1 and 4 rise and fall together), but after consultation with a friend of mine who knows more about this stuff and who was exceptionally patient and helpful with my many questions, I went with the low-tech method of stickin' a straw down the No. 1 hole moving the engine back and forth to find the highest point.
I used one from a Circle K Polar Pop - at 75 cents for a New-York-City-taxable-sized jug o' soda, they're the best deal going. And they come with reeeely long straws. And unlike screwdrivers, straws won't scratch the piston.
Problem now was, TDC appeared to be somewhere between even with the crankcase split, or just past it, as originally noted. Then things got weird.
I slathered everything with a 50/50 mix of moly lube and engine oil, according to the manual, put the cams in place and put the timing chain on, but when the crankshaft mark was aligned with the split at the case - as per the manual - with the chain pulled tight the marks on the cam were off regardless of what tooth the chain was on.
However, when the marks on the cams were right, the crank was... just past the crankcase split, where it was before I disassembled the thing. Since that's how it came, that's how I decided to reassemble it.
I found it easiest to put the exhaust cam in first, then the intake. However, the chain would slip and do stupid things while I tried to put the intake cam in, so I attached it to the exhaust cam with a zip tie to keep things from shifting off the proper tooth. Worked a treat. The white zip tie is running over the frame and under the cam chain, loosely, to keep it from falling down into the case while the cams are out or being moved around.
With both cams in place and the chain loosely draped over the sprockets, it was time to torque down the cams, progressively tightening each of the 10 bolts on the caps in the order prescribed by the Holy Book of Triumph. What the scripture doesn't tell you, though, is that the cams will turn slightly as you tighten them, on accounta the cam lobes contacting the valve buckets.
Fortunately, each cam comes with a cast-in hex nut gizmo so you can make a fine adjustment with a wrench once the caps are bolted down (and _before_ you tighten the chain!).