Monday, February 24, 2014

George's Recommendation

I finally ran into George Rahn, our local BMW airhead guru, at the College Coffeehouse. He agreed that since the water isn't from condensation in the tank, it must be from frost or ice building from air moving through the carb due to numerous short trips. Any moisture that builds up inside the engine block from condensation will get blown into the intake plenums due to the plumbing within the airbox. As far as a path into the carburetor bowls, he believes that it would be through the atomizer where the needle from the slide fits in. This is circled in green on the diagram and is right at the bottom of the carb throat. Any moisture or frost built up on the slide or intake would run right down the needle to the main jet when the engine isn't running. With the engine running and the carbs nice and warm, any moisture would go right into the engine and get burned. I had thought that the needle had closed off the opening  but George said that there would be plenty of room for water to find it's way down. What is pictured here is the position of the slide at idle (or off).

His suggested solution would be to find some foam and route air from cooling fins on the heads and cylinders around the carburetors. He had done something like this years ago using packing foam and aluminum foil and routinely rode at temperatures well below what I'm doing right now. He thinks that the RT fairing would help to hold things in place and depending on where you have the air exit, would also provide a little heat to your legs and feet which is why he did it. With this setup, he had never experienced the water problems that I seem to be having.

Right now, I have a new minor problem. The sidecar tire is flat. I think that I'm just going to pump up the tire and head for home. I'd rather deal with the flat there than in the parking lot.


  1. Richard:

    I'm glad that you now know where the water is coming from. Hard to believe that you had so much condensation from there

    I would have done the same with the flat tire. Just pump in the air and bring it somewhere to fix. Hope you made it home before the air came out

    A weekend photographer
    Riding the Wet Coast

    1. It was pretty flat once I got home but there isn't much weight on the sidecar wheel so no real problem. I already have it patched, it was a tiny hole from a burr on the inside of the rim. Easy fix but much easier in the heated garage.

      I also zip tied some old closed cell foam around the top and side of the carbs, open in the front to pick up air moving across the cylinders. Not very pretty but enough to see if it helps.