A Lesson In Simple Solutions

[kmisterk]

Hi all! First time poster, wanted to share an anecdote experienced recently that I thought y’all would appreciate.

Note: this is a story. The issue is resolved and this is purely for entertainment.

I recently acquired a 1980 r100t/7. Like many other stories similar to this one, it was extremely well maintained with a fantastic history of work and maintenance done on the bike. Blue paint, matching blue windjammer fairing, great shape, save for some minor aesthetic quirks. Nothing outside of normal for a 40-year-old bike.

I live about 95 miles from where I acquired it from. The individual received it from his step dad, the original owner, and it had been in storage for ~3 years waiting for room in the current owners garage to make use of it in any form. I took it off his hands instead. He informs me of the bikes immaculate functionality and, once the old fuel and new fluids are cycled through, it’ll run just as good as ever.

The day comes to drive it home. Right on. I coerced my dad to take me out there to get it and to follow me home. It struggled a bit at first, but after about 10 miles, it seemed to find its legs and showed me its finesse.

We get it home with no issues, save for a stop to refill the air in the back tire. I knew beforehand they were old (9 years old, 3 of which they just sat in storage) so I was lucky they were holding air at all. Goes to show just how well-kept the bike was overall.

Anyway, the next day, I take it for a cruise through town for some errands. Hair cut, new gloves, tire shopping, etc. On the final stretch of mileage back to its mooring, it starts acting like it’s had its legs kicked out from under it. Bogging down, no power, eventually sputtering out entirely.

Great. What happened? Try for a couple minutes to start it back up to quickly realize the battery is not charged enough to turn the engine over. Bummer. Furthermore, fuel tank seems low but it doesn’t seem to be out? Writing it off as an illusion, it had looked like half the tank was more full than the other. Huh, odd.

Thanks to a few friendly biker enthusiasts who stopped to lend their aid (I love the motorcycle community for that), I’m fueled up again and the battery is good enough to crank it over and get going, but for the remaining 2-3 miles, it would not give me power under load. I essentially had to stagger and stumble home at a fraction of the speed limit. Thankfully, wide shoulders made it easy to be avoided by passing traffic.

Okay, time for the troubleshooting rabbit hole. Not only is this my first bike, but it’s also my first ever carbureted engine, period. I spend a few hours reading up on the basics of a carburetor and another hour or so investigating specific issues that showcase symptoms of a similar nature and discovered that the bike is likely suffering from fuel starvation.

I get to work checking the basics, starting at the gas tank. I switch the petcocks on either side to their “off” positions and loosen the hose attached to the fuel filter half-way down to the carb. Fuel spills. And doesn’t stop.

I immediately think it’s a broken/faulty petcock. Just to make sure the current setting engaged correctly, I knock it back up 90 degrees to the “on” position and…the flow stops.

As it would turn out, the petcock has a small plastic cover with the labels of each position imprinted on it. This plastic cap, somehow, had gotten rotated 90 degrees, and thus ever since I had it, was falsely indicating that it was on, but was actually off. Heh.

With the cap fixed and both fuel lines flowing as they should, the bike is now running flawlessly. I couldn’t be happier with it.

Moral? Sure. Don’t forget, ever, to check the simple solutions first.

[Rob]

That's great! Yeah, having one of those covers move would be a problem. I never saw it happen on my '79 in 35 years, though. Not surprised it could happen, though.

You probably had one petcock on, and one off, but the crossover wasn't sufficient to feed both carburetors, which probably need some cleaning, no doubt.
That would also account for one side of the fuel tank being lower than the other. Some will splash over, but you will be happier with both taps on. That said, some folks use that method to have two reserves. Run on one side until it goes to reserve, then switch on the other side. My R65 only had one petcock from the factory, so I never got to try that one.

I also recommend you empty the fuel tank and flush it, if you haven't already. Get any water out that might be in there.

The stock charging system is just adequate on a good day. If it has a lead-acid battery, consider upgrading to a sealed unit. I'm sure the guys can recommend a current model. I don't remember which one I had (black w/orange top). I bought it, and never bought another until the day I parted out the bike.

[Steve in Golden]

Occam's razor strikes again!

Welcome to the forum kmisterk!

Photos, we need photos of the bike pls

[melville]

Welcome to the board! So happy for simple solutions.

[Zombie Master]

Welcome. I just spun mine around the other day.

[Rob]

Welcome. I just spun mine around the other day.

The levers or the faceplates?

[Zombie Master]

Welcome. I just spun mine around the other day.

The levers or the faceplates?

The faceplates. I never look at the facelplates.

[Rob]

Welcome. I just spun mine around the other day.

The levers or the faceplates?

The faceplates. I never look at the facelplates.

How about your first day with your first motorcycle? Did you ignore them then, as well?
Gosh, I wish I had been born with the wisdom of the ages...

[Rob]

Petcocks can be rebuilt.

Karcoma: https://youtu.be/JU_9f7J4JP8

Germa: https://youtu.be/QW3dCUSQJUI

You will want to drain the tank so that you can drop both petcocks and check for debris and make sure that the screens that go over the outlet tubes are in place and looking good.

[barryh]

The faceplates. I never look at the facelplates.

Me neither.

It's hard to look at the face plate while riding the bike so everyone needs to know that the reserve position is up.