TOPIC: New/old airguide speedo

I just installed a speedometer I bought at a swap meet. It works well until I get to 20mph then it stops advancing.

Is this a gag??
Push the speed lever for your motor to go faster than 20.

They work on air pressure. Could be as simple like a spider web inside, dirt/debris in the tube line, dirt or something preventing the "spring thing" from moving more or an air leak in the tube from the transom.

You can test it by actually blowing into the end of the tube or use an air compressor connected to the speedo. My first suspicion would be an air leak somewhere or a kink in the line.

Not a gag the gps had me doing 29 but the speedo stopped at 22. It was accurate up to 20. I was just wondering if the location of the pitot tube may have something to do with it. It may be just because it is ancient like me. (Ican walk but can't run fast anymore) I paid $15 for it at the Famoso (Bakersfield ) March Meet's flea mkt. I bought it because it matched my tach. I am glad it works to 22mph. It looks good in the dash.

I think you got a good deal. Those things are not very accurate at any speed and to compare it to a techy GPS is apples and oranges. I'd be happy with it, ya got something that looks good and you like it.