Backfire Moto

Yesterday I took the bike to my first Backfire Moto event, a local vintage motorcycle meet-up that happens on the 3rd Wednesday of the month. Last night was Backfire Moto #37. The bike ran great, no problems and good power. Here are a few pics. Only the red Honda SL350 is mine. The other pics are a few of the other bikes that were there (there was probably around 100 bikes there).

What Next?

OK, in my last post I mentioned that I was going to try and top up my battery. After an overnight charge on a 1 amp float charger, it only got up to about 11.36V and was falling (with nothing attached to it). The battery definitely seems toast. I took it to the auto parts store and asked them to load test it. They said that they don't load test motorcycle batteries. But they did have some other sort of tester, which they attached to my battery. It said that I have 0 cold cranking amps. The battery is only 6 months old, but I guess I have to replace it anyway.

Another potential problem, my new voltage regulator/rectifier is allowing my DC voltage to climb to over 16V at higher RPMs. I am hopeful that this has something to do with the bad battery. But I'll have to wait and see.

Got the new battery, filled it with acid, and gave it an initial charge. I put it on the bike, and thought that everything would be good to go. But, it wasn't.

The good news is that the issue that I was observing with the regulator/rectifier unit was indeed caused by the bad battery. With a new battery in the circuit it now doesn't go above about 14V. The bad news is that it ran like crap again. It didn't want to idle and it had no acceleration power.

I pulled the spark plugs. The right plug looked fine. The left looked dark and wet. I pulled the cover off of the points housing. The right cylinder points were sparking, the left were not. I pulled the left plug wire off with the engine running. No change. Clearly the left cylinder is not firing at all. I started to suspect the coil. As far as I know, you can't buy a new replacement coil identical to the original. You either get to modify or buy an old coil. And they aren't cheap. But, before assuming the coil was bad, I wanted to check for wiring problems. I undid my charging system wiring mod (the one that bypasses the headlight switch). No change. I pulled the tank and checked the wires to the coil. I noticed that the connector for one of the wires wasn't fitting snugly. And as I unattached and reattached it a couple of times, one of the connectors crumbled. I created a new pigtail to bypass the bad connector. Boom, I get spark on the left.

Well, it was after dark and getting late so I haven't done a thorough test. But my one trip around the block went great, the best power from the bike yet. Of course I need a longer test, but I am encouraged to say the least. I will consider redoing the charging system wiring mod. And the clutch needs adjustment. But I am shooting for a trip to Backfire Moto tomorrow night.

Charging Sytem Upgrades

Given that my charging system appears to have problems now, as I fix it I might as well upgrade it a bit. Apparently these bikes have always had a charging system that was barely adequate. And that was in 1971, before bikers ran their headlights all day. And on a bike that didn't come with turn signals (which I have added). So, I decided to do these two mods:

headlight switch bypass mod: http://www.hondatwins.net/forum/viewtopic.php?f=53&t=6185
regulator/rectifier mod: http://www.hondatwins.net/forum/viewtopic.php?f=46&t=14530

The first of the 2, on my bike, will only help when the headlight is off. That should be pretty much never. But I can see turning it off to try and limp home if I have another charge issue.

The second mod allows me to replace the existing regulator and rectifier on my bike with a single combined rectifier/regulator unit. Here are the old bits:

The stock voltage regulator

The stock rectifier. I dissembled it to get the wires out, I intend to reuse the pigtail.

I replaced both of the units above with this new combined unit (front and rear view):

I modified the pigtail like so:

Here is the modified pigtail attached to the new unit:

And here it is attached to the bike (where the old rectifier was mounted):

Unfortunately I cannot yet report on how it works. It appears as though I may have killed my new battery by discharging it too many times. I am going to try and top it off and see if it works. But if not, I will have to get a new battery and then test this mod.

Still Tuning

OK, so I haven't posted in a while. What have I been doing? Lots of tuning, some repeating old work but trying to do it better. For example, twice I adjusted the point gaps and set the timing. But I ended up doing it a 3rd time when I decided to put in new points and a new condenser. Similarly, twice I have disassembled and cleaned the carbs. But I just did that for a 3rd time with new internal parts (i.e. jets, needle, gaskets, etc.).

The bike now seems to run a lot better, but only under certain conditions. First, it is harder to get it started. Once it starts it runs well and has more power ... for a while. Twice I have ridden it to work. It ran well, both time, for the initial part of the ride. But it was running rougher by the time I got there. Both times I was barely able to keep it running for the trip home. I concluded that it ran fine cold, and even warm, but hot was a problem.

That is until I discovered another problem. The charging system wasn't working correctly. I had attributed the change in how the bike ran to its change in temperature. But I now think that it was simply how long I rode. You see, I was putting the bike on a trickle charger at home. But when riding it, it eventually drained the battery to the point where it runs poorly. I am now putting this theory to the test.

Turn Signals Working

With the switch mounted and a new electronic, universal motorcycle flasher installed (the one I bought previously was mechanical and failed to work properly) I was ready to wire up the new signals. I mounted the front signals to the sides of the headlight can, as they are on Honda CBs. For the rears I made two brackets (one for each side) that I screwed to existing threaded inserts I found on the frame, and mounted the signals to these brackets. Note that I had some initial problems getting the signals to work due to insufficient grounding. The signals have case grounds, so I used ring terminals attached to the turn signal post mountings to ground all signals to a good ground (there was an available green wire under the seat and one in the headlamp can). Here is a short video of the working signals:

Turn Signal Switch Install

With my modified turn signal switch in hand, I set out to install it on the bike. The first thing to do was to remove the old horn-only switch. I unhooked the wires from within the headlight housing, disassembled the switch housing and tried to pull the wires out from inside the handlebars. They were in there fairly snug. Unfortunately I ended up tearing the wires off of the original horn switch, but I got them out. To facilitate installation of the new switch, I had attached a piece of string to the old wires before pulling them out of the bars. I now had a string running through the handlebars, along what would be the route of the new wires.

Well, that all sounds great. But there was a problem. The old hole, to get wires into the handlebars from the switch, was too small. The new switch has more wires and requires a larger hole. How was I going to drill out the hole without loosing the end of the string running through the bars?

Well, I decided to push the string just inside the bars and then drill the hole. I was hoping that I'd be able to fish it back out somehow. The string ended up slipping too far into the bars and I was unable to see or reach it after drilling. The solution I came up with was to use air to blow the string back towards the hole. I don't have an air compressor, so I used that canned air you use to clean out electronics. It worked great!

The switch housing had a pin in it which protruded towards the bars, presumably to make sure the housing is properly oriented on the bars. Since my bars lacked a receiving hole for this pin, I just cut it off and ground it down flat.

After much wresting and a bit of re-soldiering, after I tore a wire loose from the switch, I got the new switch wires run and the housing mounted. Unfortunately it is not perfect. I cannot get the housing to close all of the way. I don't have a good picture of it, but there is about a 1/8th inch gap between the upper and lower parts of the housing. The wires internally are keeping it from closing. I'm not sure what to do about it, perhaps I started from the wrong switch. But for now it is installed sort of. Fitting the new switch was by far the hardest part of adding turn signals to the bike.

Modding the Switch

As I mentioned in a previous post, the original, optional, turn signal switch for this bike is nearly impossible to find (unless you are willing to spend exorbitant amounts of money for it). Sources a reasonable replacement, from another vintage Honda, is a problem also because they all seem to have one of two issues:

1. They have a headlight hi-low switch on them. On the SL350 that function is already controlled from the other (right) handlebar switch.

2. They have the base of the clutch lever, and rear-view mirror mount, cast integral to the switch. On the SL350, there is a separate bracket for the clutch and mirror.

So, I bought a switch (aftermarket part, like the vintage Honda switches but not for a specific model) that had the clutch and mirror mounts, and decided to try and modify it to resemble the original. Here is a picture of the part before I started (the protrusion on top is where the clutch and mirror mount):

I began by cutting off the bulk of the mount with a sawsall:

Next I used a rotary grinder to further shape this area. And then I sanded the results of that.

 

Lastly I painted it, and then I was ready to go, or so I thought.

Turn Signals

Well, so I've been contemplating adding turn signals to the bike for some time now. I just think it would be safer. I mean, you can use hand signals and all, but not always when you want. The signal hand is also the clutch hand. Plus, I've been getting mixed messages about whether or not they are required by law in Washington. Some say that the bike is grandfathered in, due to its age (it didn't have signals when new, it doesn't require them now). Some say that the Washington turn signal laws don't apply to motorcycles. And a lot of web sites list Washington as a state that doesn't require them. But the RCW that applies to turn-signals seems to suggest otherwise:

http://apps.leg.wa.gov/rcw/default.aspx?cite=46.37.070

So anyway, Ive started the process of trying to retrofit the SL350 with turn signals. Apparently these were optional items when new, though I think few had them. The parts for the SL350 specifically, like the handlebar switch, are nearly impossible to find. But there are available substitutes from other vintage hondas. Here is a little video of some initial testing of some of the parts I've acquired.