Friday, July 25, 2008

Brigitta does not like hot days

So this week we had some days where I was riding home on Brigitta and the temps were in the low to mid 90s, pretty hot.

Near the end of the ride, she'd sputter like she was not getting fuel when at low revs on the engine and now she consistently dies at idle while at a stoplight or while slowing down to a stop at least once a ride. Rather annoying even though she starts right back up. Another annoying symptom is that she will not hold idle after riding in a moderate rain, have to keep the throttle twisted a bit when stopped at lights. I am sure these are all clues, just don't know enough to figure it out yet, but I will.

I'd checked for kinked throttle cables, nope. Took the tank off a couple of times to ensure all electrical connections and ground wires are nice and tight. I even loosened the gas cap when the symptoms appeared today to eliminate vacuum building up in the tank due to heat, nope.

Clem, the vintage BMW mechanic at BMW of Denver also advised me today that I was missing a rubber gasket on my gas cap so he did not believe it was a vacuum buildup issue in the tank.

Today when I got home I learned how to and took off the bowls from each carburetor. I checked that there was good fuel flow from each gas line. I confirmed that the floats from the right side carburetor floated on gasoline with about 1/3 of them out of the gasoline. When I went to do the same check on the left side carburetor floats, I found a problem.

Mind you, its not probably THE cause of the sputters of late, but still, a problem. The outboard metal post where the mounting rod that holds the floats' tab was broken off! Yep, nothing really holding that end of the rod except the other end of the rod in the inboard post. Still, it seems to function fine.

You can clearly see the end of the float mounting pin appearing to be handing in thin air.

Here, you can it's actually the metal tab of the floats that helps hold up the pin.

06AUG08: Note, the hole you see above where the pin is, is not the stock hole, I'd drilled it there while trying to implement multiple fixes, all of which failed and caused overflow of the carburetor.

I plan to take Brigitta to Pete Homan next week, he's at the Paonia Beemer Rally this weekend, and show him the damaged post to see if he offers to fix it since I bought the motorcycle in that condition from him. We'll see what he says. Update: 06AUG08: Never did ask Pete about this.

IN the meantime, I am penciled in for 23SEP to drop off Brigitta at the BMW of Denver dealer. I hope to be able to figure out what's really causing the hot engine sputtering at low revs before then.

Brigitta is still rideable for short rides like my commutes and as long as I don't lug the engine when its hot outside, she behaves quite well. Still, the wannabe wrencher in me wonders, what's causing this?

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