Throttle return spring examples
Posted: June 16th, 2011, 4:10 pm
I'd love to see some examples.. It's something I've been having trouble with for the past year. I've tried a few different options and they all work to varying degrees, but I don't think I've found the ideal one.
I used to have a spring that went from a plate on the throttle shaft (on the side opposite the throttle cable end) to a plate coming out of one of the carb top's screws. It worked, but it seemed that to close the throttle completely, I needed a very strong spring, so the throttle pedal was a bit too stiff. Using a more moderate spring, the throttle would close partway, but would always be cracked open a bit. I would set my idle to 1100 or whatever, blip the throttle and it would rest at 1500.. If I pulled the throttle back by hand a little bit, it would close all the way and idle where I wanted it to. Maybe the throttle shaft was worn out too much? Didn't seem too bad..
Then I moved the spring to the throttle cable end side, same arrangement - pulling on the throttle cable end, up to the top of the carb. Worked great, but the idle screw interferes with the spring and I worry that it would either catch eventually, or rub the spring until it breaks.
Now I have the spring being pulled diagonally, built a little bracket behind the carb and the spring pulls back and up on the throttle shaft. Seems to work OK, but the throttle cable end arm, where the spring is attached, is pretty long, so the spring needs to stretch A LOT to do it's thing. Also makes the throttle pretty stiff, but I can live with it at this point.
Just curious to see what sort of clever engineering people have come up with.. What I have now works, but I'm sure could be improved.
I used to have a spring that went from a plate on the throttle shaft (on the side opposite the throttle cable end) to a plate coming out of one of the carb top's screws. It worked, but it seemed that to close the throttle completely, I needed a very strong spring, so the throttle pedal was a bit too stiff. Using a more moderate spring, the throttle would close partway, but would always be cracked open a bit. I would set my idle to 1100 or whatever, blip the throttle and it would rest at 1500.. If I pulled the throttle back by hand a little bit, it would close all the way and idle where I wanted it to. Maybe the throttle shaft was worn out too much? Didn't seem too bad..
Then I moved the spring to the throttle cable end side, same arrangement - pulling on the throttle cable end, up to the top of the carb. Worked great, but the idle screw interferes with the spring and I worry that it would either catch eventually, or rub the spring until it breaks.
Now I have the spring being pulled diagonally, built a little bracket behind the carb and the spring pulls back and up on the throttle shaft. Seems to work OK, but the throttle cable end arm, where the spring is attached, is pretty long, so the spring needs to stretch A LOT to do it's thing. Also makes the throttle pretty stiff, but I can live with it at this point.
Just curious to see what sort of clever engineering people have come up with.. What I have now works, but I'm sure could be improved.