Let's check clearances

After a month, yeah, we've been at this a month... we can finally get to the valves. Before cracking open the valve covers, take time to clean things. I wiped down the motor, under the air box, the oil cooler, oil lines and anywhere I thought I'd brush up against. While crayons, bats and small children probably won't fall into your motor, grit and grime and sand and chunks o'crud will. I also wiped down the deck of my bike lift too.

I decided to start with the horizontal cylinder. The valve cover on top (intake) is straightforward. Loosen the 4 hex head bolts and pull the cover and gasket. The bottom cover (exhaust) is tricky. Tricky because there's not a lot of clearance between the bottom bolts and the extensions upon which the oil cooler mounts. I had to make a special allen wrench, just cut down the short end so it could fit in there. The other trick is the 2 tbs of oil that's under the cover. As soon as you loosen the cover, it oozes nicely down the head and onto the header pipe. The towel you notice in the photo below left is to wipe up her drool. Below middle are shots of 2 tools I've fashioned; the aforementioned shorty allen and a pipe (tobacco type) knife. The pipe tool has a tobacco tamper on one end which I wrap in electrical tape and use a closer rocker depressor.





With the covers off, we're still not ready to measure. We need to be sure the horizontal piston is at TDC compression. Pull the left side spark plugs. I pull the lefties so I can feel for the air to escape while turning the motor or I can put a chopstick in the spark plug hole and watch it move up/down as the piston does so. I use the engine turning tool. Remove the small cover on left side of the motor to expose the crank, insert the engine turning tool and align the tangs. Use a 13mm wrench to tighten the nut on the tool and you're ready to turn motor.


Tricks for finding TDC? Method 1, check the timing marks on the layshaft pulley. I didn't use method 1, but did check after I used method 3. Method 2, take a look at the flywheel mark. You need to remove the sight glass cover on the crankcase. In the top left photo above, it's the little hex headed cover above and to the right of the crank cover. Calling it a sight glass cover is not quite right as there is no glass when you pull the cork (it's not cork, either). It's just a hole and the mark on my fly wheel is about a 1/4" indentation on the outer rim. It doesn't photograph well, so I don't have a pic. This is also in line when I use method 3. OK, method 3 is the chopstick method. Turn the motor until you feel air escaping from the spark plug hole (air escaping from the hole means all the valves are closed). Then put the chopstick or similar harmless stick into the plug hole and turn the motor until the stick tops out. Be careful not to let your stick slide along the top of the piston and get wedged between the piston and inside edge of the spark plug hole. There ya go, TDC compression.

Since measuring clearances is a 2 handed operation on a lot of it, I don't have pics. The opener gap is pretty straightforward. Slide a feeler gauge between the opener rocker and the opener shim. I start small and work up one gauge at a time until I get resistance to insertion. The gap I note is the one just before the resistant one. For the closer clearance, I use the loaded gap method. Push down on the closer rocker, then measure the gap between the opener rocker and opener shim. This is my loaded gap. The closer gap is (loaded gap) - (opener gap). Write everything down and then see what needs to be dealt with. Here's how mine turned out....

Exh Open: .06mm (too tight)
Exh Load: .07mm
Exh Close: .07 - .06 = .01mm (t00 tight)

L Int Open: .05mm (too tight)
L Int Load: .08mm
L Int Close: .08 - .05 = .03mm (too tight)

R Int Open: .13mm (ok)
R Int Load: .23mm
R Int Close: .23 - .13 = .10mm (good)

Ideally, I get .10mm gaps on the intake openers /closers and exhaust openers and .o5mm on the exhaust closer. Add .05mm to the ideal for the upper end of the acceptable range. Looks like I have some shims to change. OK, that's where we'll go next time.