what is secondary diafraghm on Hitachi Carb

[smelly_cat]

It appears that when I accellerate my carb does not return to idle. so I be bop around idling at 3000 rpm. its very annoying. I cut off the engine and restart and the throttle resets until i mash the gas hard.

Does the secondary diafraghm have anything to do with this?

It seems that when I poke a screw driver in there around this diafragm . I can knock the idle back to 1000.

I don't know if I unhooked a cam that is supposed to hit it or if I put the wrong vacumn line to it

Any one a clear picture of how all Hitachie carb is supposed to look?

83 1800GL

SC

[TheSubaruJunkie]

There's no line that controls the diaphram. It uses vacuum thats supplied from the side of the carb. Where the diaphram mounts, there's a port... and it gets its vacuum from there. There is a gasket between the carb and diaphram, and if that is leaking you may experience problems like this.

 

The mechanical lever may also be sticking. Might wanna try some penetrating lube and work it in the diaphram to see if that helps. I'd try that 1st.

 

-Brian

[smelly_cat]

Thx Junkie, I sprayed a ton of carb cleaner on the linkages, poked around with a screwdriver and worked the pedal some. I still get a throttle stick when I floor it and it revs a 3000 but now it seems like i can kick the pedal and the revs will drop to about 1500. This seems to be an improvement. In the past I had to shut the engine off and restart it to get the rev to drop under 2k. SO that is kind of cool. I think I need to pull the horn of the carb all apart again and see if I can find something hinky. or maybe it will work itself out. I need to get some WD40 and blast the linkages just in case its something easy SC.