vaccum gauge on a motorcycle - Fuelly Forums

Click here to see important news regarding the aCar App

Thread Tools Display Modes
Old 06-07-2006, 05:37 AM   #1
Registered Member
GasSavers_Ryland's Avatar
Join Date: Mar 2006
Posts: 1,325
Country: United States
Send a message via AIM to GasSavers_Ryland
vaccum gauge on a motorcycle

I just put a vaccum gauge on my motorcycle (1974 honda cb125) I drilled the intake manifold and put a hose nub in, pluged the hose going to the gauge in a few spots with filter foam to slow keep the gauge needle from going crazy.
it idles around 10 inches of mercury, and that is simply the highest I can get it, and normaly driving is around 3-4 inches, down hill throttle fully closed it jumps up to around 15-20" depending on the hill.
if I open it wide open, it drops down to 0-1".
so should I just aim for keeping at at 4" for best mileage?
I was also thinking that if I can find an affordable motor controler that hooking that up with a vaccum switch that kicks in around 1" to give it an extra boost of speed under acceleration might be fun.

GasSavers_Ryland is offline   Reply With Quote
Old 06-07-2006, 06:25 AM   #2
Registered Member
95metro's Avatar
Join Date: May 2006
Posts: 498
Country: United States
Since installing my vacuum gauge ( I have found that the reading is far too variable to be of any more use than a very vague reference point.

I hardly look at it anymore since I kind of know where it is sitting at any given point. However, I keep it installed since it also acts as a diagnostic tool (and it looks kind of cool).

Vacuum at idle is largely dependent on ambient and engine temperature. When I first installed the gauge it was cooler outside and my first test was with the engine cold. On a hot day with the engine warm the gauge hovers around 19 in. Hg without a problem (17 to 22 is normal for cars - I have no clue what is normal for a bike).

So, overall I guess I'm trying to say that you can try to keep the needle at a certain point, but even slight throttle changes, inclines, declines, and rpm highly affect the reading.
95metro is offline   Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Publishing Fill-up Stats from Mobile Site? smknipe Fuelly Web Support and Community News 2 06-22-2011 05:27 AM
epa estimates cseverens Fuelly Web Support and Community News 2 06-09-2010 03:48 AM
Custom Currency memox Fuelly Web Support and Community News 1 06-01-2009 11:56 PM
iPhone WebApp? Billie Fuelly Web Support and Community News 11 08-09-2008 11:59 AM
apexing turns kickflipjr General Fuel Topics 10 04-14-2006 07:24 PM

» Fuelly iOS Apps
No Threads to Display.
Powered by vBadvanced CMPS v3.2.3

All times are GMT -8. The time now is 04:22 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2020, vBulletin Solutions, Inc.