I put my stock carb back in this evening to do some experimentation and comparison against the Bill Blue Pumper, and that meant reinstalling the other throttle cable.

So I got it all back together and the lengths set correctly. Then I reinstalled my Acerbis fuel tank. Crap. Now when I open the throttle, it doesn't close. The tank is playing havoc with the cable and it's already at the end of its adjustment.

Out of frustration, I disconnected the push end from the carb. It works fine. It opens, and when I release the throttle, it closes. So... what exactly is the point of the push cable? I went for a ride around the block and it seemed to be just fine.

Is there a good reason to F with it til it works?

Rob

 

A sticking throttle can ruin your whole day.

 

Yeah I could see that bring a problem. But the Mikuni pumper that Bill Blue sells doesn't use a push cable either.

Rob

 

I think it's strictly a liability issue. Forever, motorcycle carbs had a pull cable attached directly to the slide with a relatively wimpy spring on top of the slide. Slides were much more prone to sticking than the throttle valve like our CV carb has. Even then, however, I didn't have any sticking slides in those old carbs...most of them old Mikuni's. While our carbs obviously have a slide, the closing cable is connected to the throttle valve, not the slide. Our CV carb has a very strong return spring for that throttle valve vs. the old wimpy slide spring that many of those old carbs had. Our CV carb has a slide spring, but it probably wouldn't do much to work against a stuck slide. I think our slide spring works more as a control device to regulate how quickly the slide opens, and of course it also assists in closure. I wouldn't worry too much about not having a closing cable attached on our carb. You could also encounter an unusual deal where the pull cable and housing could get pinched in an impact, and then you'd appreciate a closing cable...at least if the closing cable could overcome the pinched pull cable. Overall just not a big issue IMO.

 

Have all bikes with CV carbs had push/pull cables? I know that every bike I've ever seen with a regular slide carb has had only the one pull cable.

Carburetors on trucks only have the one cable as well.

I know where the red kill switch is and with a 250 cc bike I think we'll haev time to hit it if the throttle sticks. There are many other things about riding a bike that are much more risky.

 

I forgot to mention that in Rob's case with the pumper carb, they don't use a cable pull slide system anymore either. There's a fairly sturdy spring on a linkage to that slide, and it's not as prone to sticking as the old style slide spring.