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Ronkde

Airbox vacuum hose #4 confusion

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I made a topic earlier about this, then thought I figured it out and now im questioning again.

 

The bike is 01 VFR and im trying to sync starter valves. Ran into a problem when I realized that the front right airbox hose isnt connected to anything on the other end, its just plugged with a screw. I have no clue where the lower end of it was connected to, flapper? Still doesnt make sense to me how the vacuum lines go. Below the airbox theres a hose with number 4 on it, is my only choice to take the reading from there? The hose is in a tight spot so im not sure if I can get there.

 

In picture 1 is what I tried lol. In picture 2 is a #4 hose under the airbox connected to something and I figured maybe its a part of the same vacuum line as the higher #4 hose seen on picture 1. I thought perhaps ill get the vacuum reading like this but I cant feel any pulsing on my manometer hose, the other ones do pulse. Also adjusting starter valve #4 showed nothing. The clear hose part is the end which was plugged with a screw.

 

Where do I get the vacuum from? And where was this originally attached to? The earlier owner seems to have done the flapper mod but I want to return it the way it was before.

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Screenshot_20200629_195112_com.huawei.himovie.overseas.jpg

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image.thumb.png.318209fc120b450e960aa09c9652619a.png

Sorry if this is teaching you to suck eggs. The stubs on the airbox are only for securing the hoses and sealing their ends during normal operation; they are just bungs. The vacuum signal comes from the side of the intake ports under the throttle bodies. The pic below is from an eBay listing but shows the #4 hose connection at top right. You may need to lift the TBs up for access, and you will need a LOOONG philips head screwdriver to get to the clamps. Hope that helps. 

s-l1600.jpg

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46 minutes ago, Terry said:

image.thumb.png.318209fc120b450e960aa09c9652619a.png

Sorry if this is teaching you to suck eggs. The stubs on the airbox are only for securing the hoses and sealing their ends during normal operation; they are just bungs. The vacuum signal comes from the side of the intake ports under the throttle bodies. The pic below is from an eBay listing but shows the #4 hose connection at top right. You may need to lift the TBs up for access, and you will need a LOOONG philips head screwdriver to get to the clamps. Hope that helps. 

s-l1600.jpg

Terry thank you very much for this photo, exactly what I needed. I was wondering what the heck is going on but it seems the last owner has put the #4 hose to the #15 hoses spot on the solenoid. And the #15 hose was connected to the #4 bung on the airbox and the other end which should be on the solenoid was plugged. 🤭 Now im crystal clear on what to do. I wonder if the previous owner had some crazy science behind plugging the #4 to the solenoid or if it was just by accident. I dont remember any flappermod guides saying to do that. And of course I mean come on obviously my attempt of getting vacuum from the bung was just a joke... *cough* 😰

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Happy to help. For the flapper, the simplest thing to do to disable it is simply yank off the hose at the actuator on the airbox and stick a plug in the hose (apparently a golf tee is just the right size). If you were really keen you could remove the unlabelled hose between the throttle body and the one-way valve and cap the spigot on the TB, and toss the rest in a bin. Personally I left the flapper in operation as I could not tell any difference in performance, it just made more noise at low revs. All I did to my 5G was to remove the PAIR system and put blanking plates on the reed chambers, not for any performance reason, simply to get rid of all the extra plumbing.

 

Whatever you do, make sure any vacuum hoses are either connected to a device or are capped off so you don't get any unexpected air leaks back to the intakes. 

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Checked the #4 hose and yes it was connected to the solenoid. Starter valve sync done now, no clue how much 20mmHg is on my manometer but I set all to the same vacuum as #1 first and then 2 clicks more vacuum to #3 and 1 click to #4. I hope its somewhere around the right spot, atleast idle is more steady now so it cant be that bad.

IMG_20200630_114808.jpg

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The vacuum difference is given in mm Hg, which has a density of 13.6g/mL. Looks like you have oil in your tubes, density of that would be around 0.8g/mL, so 10mm Hg vacuum difference would be 170mm of oil.

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Ahh, then I am pretty close with my adjustment. If it rains today too I might go back and check if adding 1 more click to #3 and #4 gets me closer to spec.

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