Vertical cylinder is so much easier

Kids, if you've never done this before, start with the vertical cylinder. It's a breeze compared to the horizontal. I also got a lucky break, none of the closers needed to be swapped - so take my giddiness with a grain of salt. Anyway, let's recap - horizontal cyl done but gaps are now smaller, old belt was back on and we left things at TDC-compression.

We need to get the vertical cylinder to TDC-comp. I don't have a degree wheel, so I couldn't accurately rotate the turning tool 270 degrees like the factory manual says to do. But 270 deg is 3/4 of a circle so I eyeballed the initial position of the turning tool and spun it 3/4 of a full rotation. Then I finished it off with the old chopstick in the spark plug hole method I told you about a few posts ago. Once we are TDC on the vertical cylinder, things fall into place.

On a whim, I thought I try to slide the rockers without pulling the belt and rocker pins. OK, it wasn't a whim. I didn't relish the thought of pulling the horizontal belt to remove the vertical belt and risk the chance of inadvertently spinning a cam wheel to a point that I couldn't get it back to square one.

Pop the rocker arm clips off. Within a degree or two of TDC, you can slide the left intake rocker over. When you do that, you're in the sweet spot for the other two too. In order to move the exhaust rocker, you have to slide the right intake rocker over first as the intake rocker blocks the exhaust rocker. There ya go, no need to pull the rocker pins. Sweet, huh?

On the vertical cylinder, I needed to swap out the exhaust and left intake opener. Now as luck would have it, I used one of the shims I needed on the horizontal cylinder. No problems, one of the shims I pulled was a duplicate. Actually 2 of the shims were 3.00 mm, and I already had one so that made 3. The size I needed should have been .02 smaller for a min gap. Sanding down 0.02mm is a breeze. I didn't have a piece of glass but the thick aluminum insert on the bottom of one my wife's saucepans was pretty flat. I checked with a straight edge held perpendicularly to the surface across the whole plate. I looked for light peeking through any gaps. There was a small dip toward the center so I stayed away from that. 400 grit wet/dry sandpaper taped to the pot bottom and a squirt of WD40 got things going. I would sand in a circular motion for a bit, then rotate the shim a quarter turn. I'd go through 3 cycles of that, then check the thickness with my mic after cleaning the shim well. In about 20 minutes, I shaved off about .03mm. Good enough, popped the shim in and moved the rocker arm back.

I put the clips back in, rotated the motor one degree-ish to get it back to TDC and then measured my gaps. Got 0.11 across the board on the openers, 0.10 on the intake closers and .06 on the exhaust closer. I'm sure at 12k, I'll have some closer shims to change as I'm sure things aren't fully bedded in.

At this point, I moved the motor back to TDC-comp for the horizontal cylinder. Checked with the chopstick and timing marks. With all things aligned, I checked the horizontal gaps again. Nope, still really tight. I was going to go back to the 'net for help but did have new belts to put on so I thought I'd take care of that first. I pulled the horizontal and the vertical belt and just for kicks, measured my gaps. Guess what? They were spot on. So I put the horizontal belt on without tensioning it and checked. Guess what? Tight gaps. Thinking back to the factory manual and some videos on the 'net, valve adjusts are done with the head off the bike. Hmmm, those are checked with no belts / 0 tension. OK, I'm going with the unbelted gaps as fine and calling it good.

Changing the belts is simple since we have timing marks to go by on the ST3s. The only trick is to sliding the belt under flange on the horizontal layshaft pulley. It's kind of a feel thing. You need to kind of wiggle things to make sure the bumps of the belt slot past corresponding valley on the pulley. Once the belts are in place, double check your timing marks. I use a simple guitar tuner app (gStrings - it's free) on my android phone to check the tension. 100Hz is what I shot for. Took a handful of plucks to get a decent measure. Once I got it to 100Hz, I double checked with the 45 degree twist. I got a bit more than 45 degrees but decided not to cinch it down more. Had a belt drive Harley for a while and tensioning the drive belt was checked with a twist. I've always felt if you were going to err, err on the loose rather than tight side. I'll check the tension again in 1k miles. It's easy enough to do.

So there we have it... valves adjusted. Time to button things up. We'll talk about that adventure later.