I promised updates. What follows is the probably somewhat boring detail of my week wrenching on the motorcycle.
On Wednesday I started out replacing the clutch cable, since this was the part that was most obviously in need of replacement. The manual I’ve got is absolutely awful. Some examples:
“The circlip use to a set the clutch center is of a special dimension (25×1.5 mm) therefore exercise care that the standard circlip 25 mm is not to be used.”
“Headlight is normally adjusted in the vertical directions so that the center of the beam intersects the ground at the point 50 mm (164 feet) in front of the motorcycle with the motorcycle in riding attitude.”
It’s the official, authentic, Honda manual. I’ve been recommending Honda products to people for years, but this is my first one. I hope that their modern shop manuals aren’t this bad.
Fortunately, a motorcycle is pretty simple, and I’m able to figure out how most things work through intuition. The clutch cable disappears behind a cover plate that also houses the front drive sprocket. The underside of the plate was coated in solid gunk. Whenever the drive chain throws off lubricant, it sticks on the underside of the plate. I spent about an hour cleaning it. I pulled apart the clutch actuator cam and figured out how it works. Clever, but seemed a little unnecessarily complicated. The cable pulls a cam that’s got dents in it. The dents ride on top of several ball bearings. When the cam rotates, the ball bearings are in a plate that cannot rotate, and as a result, the dented plate is forced outward since it’s not riding in the dents anymore. This pushes on a lever that disappears into the other side of the bike, but is presumably connected to the clutch. I have a feeling I’ll be forced to get acquainted with that side eventually. For now, I just wanted to replace the cable.
I cleaned all the parts and re-greased the clutch actuator. I removed the other end of the cable from the handle bars and routed the new cable, which also involved removing the gasoline tank, since it goes underneath. That’s when I discovered the new cable was too long.
No matter, I figured I could find a way to route it anyway. After I finally got it all installed and adjusted, it was simply way too difficult to operate. The problem seemed to be kinks in the cable, which were a result of the cable being too long. I called a few motorcycle shops to see if anyone could shorten the cable for me. It seems a pretty easy deal if you have the right equipment. Everyone I talked to acted like I was crazy. This has been a continuous problem with the motorcycle. I don’t know how to interface with the outside world. If I wanted to pay someone to work on my 37-year-old Honda, I’m not sure I even could. Everyone who owns one of these things seems to keep it running themselves. For instance, yesterday I walked into the Harley shop to to try to buy some chain lube. Harleys have chains, I figured this was a safe bet, and the Harley shop was close. No such luck, they have none for sale. Where do Harley riders buy this sort of thing? Wal-Mart?
So, after spending most of the day on the stupid clutch cable and having not really accomplished anything I moved on to the front brakes. I thought the front brake pads were pretty well worn, and had ordered replacements. It turns out, once I got the old pads out, that they weren’t worn at all. They were glazed a bit, but had mostly full life left. I decided to change them anyway since they looked pretty well glazed, and I’d already taken them apart. Then I worked on flushing the brake fluid and bleeding the lines. The fluid was pretty old-looking, so this was worth doing. I’d figured that I could also make the brake handle firmer, but this didn’t seem to be in the cards.
Finally, just before Jonah got home, I decided to go ahead and take the carburetors off. I was convinced the idling could be made better by rebuilding the carbs.
I got them off, and took them inside and pulled them apart. I figured out what was what, removed the rubber parts and dropped the rest into a gallon of carb cleaner to soak. I had replacement o-rings for everything except the main primary jet. So, of course, the o-ring on the main primary jet on the left carb was damaged when I pulled it out.
Jonah accompanied me to the auto parts store on my quest for an o-ring. I found one with the right inner diameter, but that was too fat. I tried to cram it on there, but the jet wouldn’t go in. So I trimmed the old one with a razor blade. This ended up being a bit crude, but seemed likely to seal anyway. I measured the old one carefully and ordered a replacement from an o-ring supplier on Amazon, and went to bed. I’d rebuilt carburetors before, and they’d always been pretty gummed up inside. These appeared to be in really good shape, and not in need of a rebuild at all.
It’s unlike me to use the wrong part, but at this point, I’d only ridden the bike once, and wanted to do so again without waiting for the o-ring to arrive. The o-ring won’t get here until next week when I need to be busy studying for my airline interview the next week. It would be obnoxious to not ride the bike until after the interview.
So on Thursday, I got up about the same time Jonah left, uncharacteristically early for me. Wrenching on a motorcycle excites me, apparently. I dismantled, cleaned, and rebuilt the second carburetor. I left the problem o-ring in place this time so as not to damage it.
While the right carburetor was soaking, I changed the speedometer and tachometer cables. The tachometer cable was old and rusted, and the tachometer took awhile to get up to speed after I started the bike. This was a pretty straight-forward replacement. The speedometer cable on the motorcycle appeared to be relatively new, but it was too short, and wouldn’t fit in the appropriate mounting brackets on the front fender, so I had a replacement for that as well. Fortunately, the new one was the right length.
I put the carburetors back on the bike. At some point on Wednesday, I’d removed the pet cock from the fuel tank to check the filter screens for blockage. There wasn’t any. I only spilled about half a gallon of gasoline doing this. So, on Thursday I fashioned two new fuel lines and put in two new in-line fuel filters. Honda didn’t see fit to include in-line fuel filters in 1973, but the tank wasn’t at all rusted back then, either.
I poured some fuel back in, opened the fuel valve, turned the ignition switch on, flipped the run switch to run, closed the choke, and pushed the started switch with the throttle cracked open. It started up immediately, and seemed to run okay. Only, I pretty quickly realized it wasn’t running as well as it should, and the throttle response was sluggish. It took me a good 2 minutes to realize it was only running on one of its two cylinders. Not good.
I almost panicked, but restrained myself and checked for the obvious. It turns out the right cylinder won’t fire when the right spark plug is unplugged. Right.
I plugged it in, and it ran a whole lot better. I spent the next half an hour fiddling with the carburetors, and got it about as well as it was before. It still didn’t idle terribly well, but maybe slightly better. Content, I put on my gear, and decided to go for a short ride to test it out. I stopped at the gas station right down the street to fill up the tank first, then headed down the road. Immediately, there was a problem. It sputtered and ran like crap at about 5,000 rpm. It seemed to smooth out at about 8,000rpm, but lacked power up there, and really didn’t like wide open throttle. Also, annoyingly, the new front brake squeaked.
I was immediately disgusted that I’d made the bike run worse, and not better. I worried that I’d never make it as good as it was when I got it, and decided I was a failure as a mechanic. I’m easily defeated, what can I say?
I brought it home, dismounted and noticed that the choke was halfway closed. I’d apparently knocked the lever during my fuel stop, and there’s no way the bike was going to run at full throttle with the choke on. I turned it off, and rode again. Much better.
Jonah got home at about this time, and I offered to take her on a ride. She agreed immediately. I’d initially told her that it would probably take me some time getting used to the bike without her before I took her on a ride, but I figured I’d managed on a moped in Greece and this could only be easier.
She suited up, and we headed off. I stalled trying to get out of the apartment parking lot, right on the center line of our street. I managed to briefly block traffic before getting going again. Clutch work requires a lot more finesse with that much weight on the bike. The bike stalled as I was pulling up to the next traffic light. It took me a good 30 seconds to figure out that I’d left the fuel selector valve off. A potentially fatal mistake in an airplane, fortunately this was a motorcycle. And I didn’t have a checklist. (Should I have a checklist? I should at least have a flow.) Anyway, I managed to stop traffic twice in under 2 minutes. Nice.
The rest of the ride went without incident, and I was glad that the bike was running, if not wonderfully.
On Friday, I decided to tackle all that was left. I adjusted the valve tappet clearance, set the point gaps and the timing. None of this did much, except that I made one of the intake valves clack. I’d spent a long time with a stupid .05 mm feeler gauge trying to set the damn thing, too. Do you know how thin .05mm is? It’s really thin. Paper-thin, and flexes all over the place. I decided the whole thing was dumb, and with the engine running, I tweaked the tappet adjustment screw until the noise stopped. It was probably right-on before I screwed with it, and now it was “close enough.”
The point gap seemed a bit tighter than spec, so I widened it out. As a result, the timing was now off. I tweaked the timing until it was right, and now the point gap was too much. So I pulled the points back in, and the right side was timed perfectly, but the left was still off. So I tweaked the left side point gap until the timing was correct. The gap was still in spec, so I declared it good enough.
It still idled poorly. One thing left: I pulled the spark plugs.
Coated in black. Probably a result of running around with the choke on. I cleaned them up with some sand paper and re-installed them. It ran better than it ever has before. At least in the week I’ve been messing with it. The idle still fluctuates a lot more than I’d like, and I think there’s a subtle fuel issue at play. Someone suggested on the forums that the in-line fuel filters might be causing a problem. I’m not sure how, but I may try removing them to see what happens.
Finally, I still had to lubricate and adjust the drive chain. I started measuring the slack. It varied from a little over 1.5″ to less than 0.25″ depending on the chain position. Not a good sign. After cleaning with WD-40, it was a lot freer and most of the chain showed about 1.5″ of slack. The manual specifies 3/4″, so I tightened it up to the recommended amount, and drove downtown looking for chain lube. I eventually found some, sprayed down the chain, and got it down to less than 1/4″ of variation from tight/loose which seemed to me a pretty good indication that the chain was still serviceable.
Jonah came home and we rode for another 10 miles.
Then today was Saturday! With the bike in pretty good shape, we talked about a few different options for a ride, and decided on heading north up highway 83. Which we did, about halfway up to Denver. I discovered that the motorcycle won’t do much better than 80mph with the two of us on it, and a whole lot slower than that uphill, depending on how hard I want to push it in which gear. With a 9,500 rpm redline, 8,000rpm for any extended period of time seems a bit mean to a 37-year-old engine. At wide open throttle in 5th gear, it would pretty consistently maintain about 65mph uphill which is respectable.
We stopped several times to adjust gear and stretch. We headed north until just shy of Castle Rock and then turned east until we got to Kiowa, then headed south to Falcon and then back home. All in all, about a 3-hour, 100-mile ride. We had a great time, and the bike did just fine. And we didn’t die. All good things! I plan for more in the future, but for any distance, we either need a bigger motorcycle, or two of them. Jonah would prefer the two of them option, but that’s obviously not going to happen until I manage to find a job.