The Ride of Shame

Insurance is due to run out on the 920 so I thought I would go for an afternoon run on some local curvy roads.
I've been tentatively leaning the bike over further and further to push up corner speeds. Yesterday's test was about as fast as I want to go on any bike and it handled it with ease. With the lightweight and the high torque engine , the acceleration out of the corners is really strong, it slingshots to the next corner. It really doesn't matter much if you get it wrong and exit in a gear too high. It just pulls hard anyway.
3rd gear is the best gear for fun on this thing.

There is an old saying - "Pride before a fall" . That one got me on the ride home.
About 10 miles from home I was thinking what a great bike this has turned out to be. Just then the engine shut off, just like the kill switch had been bumped.
It turned out to be a burnt 5 amp fuse on the ignition circuit. Shouldn't 5 amps be adequate for analog Boyer?
There is one other possible issue. Getting ready for the ride, I replaced the battery, which had been in another bike. I couldn't find the proper battery hold down bolt and in the rush to go used an incorrect bolt. That allowed the battery to get loose and bounce around on its tray.

I've replaced the fuse with a 7.5 amp and will take the bike out again today.
The silly thing is that I could've replaced the fuse roadside. There are spares in the underseat fusebox and the seat comes off or goes on in about 5 seconds. That might be an age related problem!

Glen

You are not alone - as I posted in another recent thread regarding breakdown - the only time I have been stranded on my Commando was caused by a broken 30 year old unlubricated clutch cable .
Only myself to blame …

That turned out way better than I thought it would. I was thinking you might have hit the deck on the 920.

I might have to build a Molnar 920 and see what this short shifting pulling out of the corners is all about. Can't do that with a 750. Well, not with mine anyway.

Good thing you did not get hurt, and only burnt a fuse.

My battery is held securly with Velcro.

Isolates vibration and hangs on tenaciously.

Dan1950 said:

My battery is held securly with Velcro.

Isolates vibration and hangs on tenaciously.

Click to expand...

My fuse block is held onto the battery with Velcro. Yes, it hangs on tenaciously and isolate vibration.

I had one of those blade fuse holders mounted in front of the battery and removed it a few days ago. I like the idea of having individual circuits, but the vibration made the fuses come loose in my case. Every few hundred miles I had to bend the the fuse tags a bit to tighten. For now I have gone back to a single fuse for everything in a water proof fuse holder. I might go back to individual circuits later after I find a better system,

Glen your bike really looks like fun. Maybe try a 10am fuse?

I have a mini - fridge in my hunting shack that only draws 3 amps. That seems like a lot of amperage output to blow the fuse on a mtcyl. ignition system.
If your battery was bouncing around it may have shorted out that fuse on some intermittent contact it should not have made.
Putting in a bigger fuse does not solve the problem. It just offers a better chance to cook something else beyond/downrange of the fuse link.

I put a cutout in the battery tray to lock it in place and then anchored it down with a Velcro strap.

I put a 7.5 amp in there. 7.5 will blow easily without melting wires. My 650ss shows 4 amp discharge at idle with just Boyer ignition running so perhaps a 5 amp fuse was marginal.


Seems all that was wrong with the hold down was the hokey little screw I grabbed for the ride. This is a tiny new battery, the previous battery was a regular 7ah AGM. I had made a new clamp for the tiny battery. It is meant to be held down with a 1/8" Through bolt with a nylock nut on the bottom side of batter tray. I couldn't find that and thought a self tapper would hold the tiny battery for 1 little ride. Wrong!

I put the proper clamp arrangement in place today and repeated the 150 km ride, no problems.
Now to work on those expanding circles of confidence....


Glen

Richard Tool said:

You are not alone - as I posted in another recent thread regarding breakdown - the only time I have been stranded on my Commando was caused by a broken 30 year old unlubricated clutch cable .
Only myself to blame …

Click to expand...

Reading your reply made made me think about my 71 Commando. Over the years I've had plenty of roadside repairs ( install a new set of points now and then, tighten a bolt or two to stop an oil leak, fix something that came loose due to vibration...little stuff ). The only major problems I can recall was in 1979 on one of my many trips across the Majove desert from Phoenix to California l encountered a burnt exhaust vavle 100 miles from home. The Commando took me home on 1 cylinder. Another incident was in1998 riding 2up with a weeks worth of camping gear from Colorado Springs, Colorado to Sturgis ( passing all kinds of Harleys being trailered to the event - btw those HD guys really loved my Norton) and the cylinder base gasket sprung a leak throwing oil on my rear tire. With a few handy tools I was able to lift the cylinders and seal the leak. And once in the 80s and again just a couple of years ago I lost a clutch cable, but in both cases was able to ride the bike home by manipulation of throttle and shifter (and a bit of running from a stop). All in all, the old British bikes had nothing fancy and although they have their "minor" problems most if not all can be repaired on the side of the road unlike today's modern bikes. My bike has only seen a trailer once...the first day I brought it home

worntorn said:

Insurance is due to run out on the 920 so I thought I would go for an afternoon run on some local curvy roads.
I've been tentatively leaning the bike over further and further to push up corner speeds. Yesterday's test was about as fast as I want to go on any bike and it handled it with ease. With the lightweight and the high torque engine , the acceleration out of the corners is really strong, it slingshots to the next corner. It really doesn't matter much if you get it wrong and exit in a gear too high. It just pulls hard anyway.
3rd gear is the best gear for fun on this thing.

There is an old saying - "Pride before a fall" . That one got me on the ride home.
About 10 miles from home I was thinking what a great bike this has turned out to be. Just then the engine shut off, just like the kill switch had been bumped.
It turned out to be a burnt 5 amp fuse on the ignition circuit. Shouldn't 5 amps be adequate for analog Boyer?
There is one other possible issue. Getting ready for the ride, I replaced the battery, which had been in another bike. I couldn't find the proper battery hold down bolt and in the rush to go used an incorrect bolt. That allowed the battery to get loose and bounce around on its tray.

I've replaced the fuse with a 7.5 amp and will take the bike out again today.
The silly thing is that I could've replaced the fuse roadside. There are spares in the underseat fusebox and the seat comes off or goes on in about 5 seconds. That might be an age related problem!

Glen

View attachment 99815View attachment 99816

Click to expand...

If you put the fuse where I think you did in the circuit, you need to allow about 4amps for the coils and some for the Boyer itself. So, 5 is too little - 7.5 is about right.

That seems to line up with the result. Odd that the fuse held for 400 miles or so before burning, but that may be due to the cumulative effect of getting hot on each ride.
All seems happy now.
The 2.0 ah battery is an experiment. I've never used such a tiny battery on a bike before, but it seems to do the trick. Wouldn't want to inadvertently leave the lights on while going for a coffee.
Then again, a 7 ah battery might not do well in that scenario either.

Glen

worntorn said:

That seems to line up with the result. Odd that the fuse held for 400 miles or so before burning, but that may be due to the cumulative effect of getting hot on each ride.
All seems happy now.
The 2.0 ah battery is an experiment. I've never used such a tiny battery on a bike before, but it seems to do the trick. Wouldn't want to inadvertently leave the lights on while going for a coffee.
Then again, a 7 ah battery might not do well in that scenario either.

Glen

Click to expand...

Different batteries and charging systems have different voltages. You changed the battery. I=E/R (keeping it simple and only considering resistance)

Assuming 3.2 ohms for the coils I=E/3.2 (Amps=Volts/Resistance)
Volts Amps
12.0 - 3.75
12.6 - 3.94
13.2 - 4.13
13.8 - 4.31

The AH should not matter, but the voltage the battery chemistry will allow from the charging system and the capability of the charging system do matter.

Roughly: Lead/Acid 12.6, AGM 12.7-13.0, Lithium 13.0-14.0

That might be the cause. If the fuse was on the verge of burning before and amperage on that circuit increased slightly with the battery change, it could take it over the edge.
Anyway, it seems to have been an easy fix.

Glen

Jerry Doe said:

I had one of those blade fuse holders mounted in front of the battery and removed it a few days ago. I like the idea of having individual circuits, but the vibration made the fuses come loose in my case. Every few hundred miles I had to bend the the fuse tags a bit to tighten. For now I have gone back to a single fuse for everything in a water proof fuse holder. I might go back to individual circuits later after I find a better system,

Glen your bike really looks like fun. Maybe try a 10am fuse?

Click to expand...

I'm surprised that the fuses vibrate out as Commandos are so smooth, other than in that low rpm zone which I'm pretty sure you mostly stay above.
I did have that problem with fuses falling out on the 1360 Vincent prior to dynamic crank balance. Prior to the crank balance it vibrated horribly. Its quite reasonable now, but not as smooth as a Commando in the smooth zone.

Glen

Schwany said:

That turned out way better than I thought it would. I was thinking you might have hit the deck on the 920.

Click to expand...

Me, too. When Glen said "pride comes before a fall", I thought he meant an actual fall.

Hadn't thought that one thru.
It probably wasn't the best saying to use on a motorcycle forum!
"Pride comes before a fall" is the motto of the International Pony Club.

Glen