CB400 Pilot screw and hydro gas settings

Bigdave982 · Post by **Bigdave982** » Tue Mar 11, 2014 3:12 pm

Can anyone tell me the fuel pilot screw settings and hydro gas range readings for my '92 CB400?
I'm going to balance the Carbs and need to know the base settings :0)

Cheers, Dave

superv500 · Post by **superv500** » Tue Mar 11, 2014 10:01 pm

Set mine 2 1/2 out.

Unsure what you mean about hyrdo settings...

Bigdave982 · Post by **Bigdave982** » Tue Mar 11, 2014 11:38 pm

It's the butterfly setting, you adjust them and balance the carbs.
The reading provided by the carb balancer measure in Hg, "Hydro gas" no idea what it truly means but Haynes manuals always have the levels in for this reason. Sadly I can't nip out and get one for my bike as we all know!

Ben_OB1 · Post by **Ben_OB1** » Wed Mar 12, 2014 2:36 am

Bigdave982 wrote:It's the butterfly setting, you adjust them and balance the carbs.
The reading provided by the carb balancer measure in Hg, "Hydro gas" no idea what it truly means but Haynes manuals always have the levels in for this reason. Sadly I can't nip out and get one for my bike as we all know!

ROFLMAO

(never thought I'd use that ever again!). Where did you get the term Hydrogas from?

Hg is the chemical symbol for Mercury. Vacuum is measured in inches (or centimeters/millimeters) of mercury, as this is the old scale used in manometers. One inch of Mercury is just less than 0.5 PSI or 34 millibar.

My RVF was about 200 mm.Hg at idle for each cylinder when I last sync'd the carbies, I would expect the CB400 to be similar.

http://www.mcp.com.au/carbtune/

Ben.

Bigdave982 · Post by **Bigdave982** » Wed Mar 12, 2014 7:26 am

Someone told me that's what it meant. I'd no idea prior to that as no manuals have even explained it.

Ben_OB1 · Post by **Ben_OB1** » Wed Mar 12, 2014 8:36 am

Bigdave982 wrote:Someone told me that's what it meant. I'd no idea prior to that as no manuals have even explained it.

Hehe no worries. The actual values of vacuum aren't really that important so long as all cylinders are drawing the same. There should be some good reading on the carb tune website. Sorry about my laughter earlier, I was mostly laughing at myself for trying to understand what the Hydrogas value was... Slaps forehead!

Ben

Superjack44 · Post by **Superjack44** » Wed Mar 12, 2014 7:36 pm

If it helps this is how I set my carbs up from scratch after dismantling and cleaning all four carbs I inserted a half thousandth feeler guage under the butterflies from the head side and adjusted the screws until I could just feel a very slight resistance as I pulled on the feeler this gave a good base setting as I could then adjust the tickover to then accomodate the revs to suit the carbtune (Manometer) and then adjust each carb to get a good balance.
As you adjust one its possible it may throw out one or more of the others just keep checking the butterflies with the feeler guage
For the mixture settings I used a gunsons colourtune to adjust the mixture settings it was a bit fiddly but it worked for me.
I think I first set them to about 2 turns out from fully in.

CB400 Pilot screw and hydro gas settings

CB400 Pilot screw and hydro gas settings

Re: CB400 Pilot screw and hydro gas settings

Re: CB400 Pilot screw and hydro gas settings

Re: CB400 Pilot screw and hydro gas settings

Re: CB400 Pilot screw and hydro gas settings

Re: CB400 Pilot screw and hydro gas settings

Re: CB400 Pilot screw and hydro gas settings