Topic: High idle

[Bigdjag]

Hi I have a problem with my 77 cb750a. It starts up ok and when I put it in gear the revs rise as it should so it doesn't stall but if I take it out of gear it revs up way above a normal idle. It gets worse when warm. I have checked the idle solenoid and it seems to be working correctly I can feel it click as I put it in and out of gear. For some reason the high idle diaphragm seems to hold the vacuum when in neutral. If I pull the hose off it comes back to a normal idle. I have checked the solenoid by sucking on the hose and putting it in and out of gear and it works fine but when connected it holds the vacuum. Any ideas

[raymond10078]

Is the solenoid vent line open? 

[Bigdjag]

With the ignition off and sucking on the line from the diaphragm I still get a vacuum but the solenoid clicks when you put it in gear so I suspect there is something wrong with the solenoid or the hose is blocked

[raymond10078]

There are three hoses going to the solenoid.

One goes to the carb (from top of solenoid).
One goes to the diaphragm (from side of solenoid)
One is vented to air (from bottom of solenoid).

You say that when you suck on the line from the solenoid that goes to the diaphragm you get a vacuum - meaning - that you can't draw air?  If so, the vent line may be clogged/closed, as the solenoid should connect the diaphragm to the vent with no power applied.  What happens when you disconnect/open the vent line?

[Bigdjag]

Fixed, the solenoid was fitted upside down fitted it the right way and now it works as it should
Thanks for the help

[raymond10078]

Fixed, the solenoid was fitted upside down fitted it the right way and now it works as it should
Thanks for the help

Great!

I hand't considered the possibility of it being upside down.