Quick connect mod for throttle body synch with manometers XSR700 / MT-07

[Pursuvant]

Kudos to our friend  @D.A. who continues recovery from nasty high side practicing knee dragging, he modified his existing vacuum lines on an MT-07 and I'm just repeating his success. This mod will build an entirely new vacuum setup for XSR700 / MT-07 instead of modifying the existing parts, so you can keep the OEM parts for a backup or a dog chew toy or whatever.

Working this mod I was throwing "check engine" light, suspected vacuum leaks but unfortunately it simply is the Yamaha sensor begins to behave abnormally if the vacuum lines are modified too long.  Air pressure sensor starts sending unexpected responses to ECU during engine braking/closed throttle decel, flashes the "check engine" light for a second or so around 3K rpms. If you're thinking to extend the lines all the way to under your seat, best give it up. So this mod is as all mods should be, simple, mildly invasive, and delivers a "plug and play" hookup to synchronize the throttle bodies with a manometer (like CarbTune). Nothing has to be perfect, but it does have to be correct. To see how @D.A. did it modifying the existing vacuum line, read this thread. Read what he did, check what I did, and then just do it your way, it will work out.

Disclaimer - Like all my mods, this will kill you and it causes athletes foot fungus, and you don't want that

Why this mod? - You would not ask, if you have tried to synch your throttle bodies (hookup CarbTune or other manometer). Stock vacuum lines are tough to get at. Best to just make easy access vacuum lines with rubber caps - so you can pull the caps off and slip on your manometer lines and get those throttle bodies in synch without removing the fuel tank or turning sideways, backwards, upside down, or whatever is in the book.

 

Parts for this mod

HPS vacuum hose 3.5mm here

Vacuum hose clamps 8mm here

Straight barbs 4mm here
Tee barbs 4mm here
Wire spring hose clamps here
Bung caps 4mm here 

MotionPropilot screwdriver here

small wire ties (cable ties)
3/8" (or similar) thin wall automotive rubber hose (to make a heat protective jacket around new vacuum line)

2' of 5/32" inexpensive auto parts store vacuum hose, so you can make a "test loop" for your manometer accuracy check

 

Get the bike ready for the mod

(XSR700) Remove the side covers and the side cover "backing plates". Also to get some room to remove the old vacuum line and plug in the new vacuum line part we build, disconnect the acceleration throttle cable at the throttle body. It will give your fingers some room to get in there on Intake #1 (left side of the bike).

 

Building the new vacuum hose for Intake #1

We will replace Yamaha's vacuum hose that runs from the air pressure sensor (above cylinder #1 valve cover) to the throttle body #1 manifold nipple (left side of bike). Here's the part we will build

It's all made from the hps vacuum hose. Vacuum hose clamps are used to connect assembly to the air pressure sensor at the top of pic, and to the throttle body nipple at the bottom of pic. The "Tee" is our modification, that let's us add a new line for connecting throttle body synchronization tool to Intake #1. Note the "Tee" uses small wire ties (cable ties), because they tell the mechanic to "leave this connection alone!". We provide clamps where technicians can connect/disconnect, but we don't want anyone to disassemble our mod.

 

That 70mm manometer hose

That worked for me, on my XSR700. But you may want to be smart and make it twice as long (temporarily) and then cut the exact length you want after you locate both cylinder # 1 & 2 hoses you make on the bike (but remember, too long and you will toss an ECU "check engine light" on decel/engine braking). Do this for sure though - mark the outside of the hose (ball point ink pen works) at the base length I show. Hose marks become reference marks on your longer hoses until you are ready to make the final "cut", and use the rule if you extend one you extend both same length beyond reference marks. Keeps total vacuum draw equal on both pieces, to prevent "skewing" the manometer readings between throttle bodies.

 

Add a heat jacket

Take a piece of 3/8" thin walled rubber hose, cut it 90mm length, then slit it all the way so you can open it up like a jacket and wrap it around the hps vacuum setup

That's enough to protect hps from cylinder heat, hps doesn't really need it but let's do this the correct way. If the jacket is loose, you can put a zip tie around the whole thing just under the "Tee", and don't make it tight - you don't want to restrict the hps vacuum line inside in any way.

You are ready to install just as it appears in the pic, the top plugs into the air pressure sensor, the bottom into intake #1 manifold nipple, and once installed you will see the easy access tube is sitting nicely hidden behind your side cover so nobody will jerk with it, but you know it's there when you need it. To remove the OEM vacuum hose, and to install the new part, use some needle nose pliers, but be kind to your product, don't do any damage to your part or the bike nipple and sensor when you plug it all together.

Here is what it looks like once installed, (the side cover (and backing plate) were removed to do the install of the vacuum hose). The hose is nicely waiting for you to remove the bung cap, and plug into your manometer. And once you put the side cover and backing plate on, nobody will know it's there and mess with your bike.

Next step, build a new vacuum hose for Intake #2 (right side of bike), and it's just a simple line with a bung cap on the end.

 

Building the new vacuum hose for Intake #2

Let's work cylinder #2 on the right side of bike, and build a line to give it the same kind of easy access. Just follow the pic below. Like the cylinder #1 hose, if you want leave the hose longer than needed for the moment but be sure to make a reference mark at the 160 mm, so you know where I cut (and you can make both hoses longer, but the same amount of length longer than my hoses).

Ya, that was tough work, I know. This is all you need for #2 intake vacuum hose. On the #2 intake manifold there is a nipple just like the nipple on #1 intake, only it just has a simple blanking cap and wire clamp closing it off. Remove that stock OEM blanking cap from the #2 intake manifold and plug your new 160 mm hps hose (you built from the pic above) into the manifold nipple (it's tough, tight to get in there, but you only have to do this once, that's the whole point of this mod).

Bring the other end of the new vacuum line with the bung for connecting synchronizing tools up and out where the right side cover will hide it from folks you don't want messing with it. Very easy to just tuck up under the side cover mounting bracket. This right side vacuum hose is 160mm for a reason - that's the length of the vacuum draw on the Intake #1 hose, we want the lengths to be essentially the same.

 

That's it. Now let's test our manometer to see if it is accurate, and then hook it up to synchronize throttle bodies.

 

Build a test loop for manometer

Assemble the loop you see below

We use this setup to connect the single line at top to the Intake #2 easy access bung, and then the "two" lines below can be connected to two of your manometer tubes. If the manometer is accurate, the two tubes will have the exact same reading when you start the bike for a test.

Edit 2022-07-30 - Always plug the test loop into Intake #2, because it will cause the air pressure sensor on the #1 vacuum line to throw an error.

Go ahead and plug it into the bike Intake #2 easy access and to your manometer (I have a CarbTune shown below). Start your bike and you can check the manometer, are the readings the same? They better be, because both the manometer tubes are connected to a single vacuum source, our Intake #2 easy access bung.

If your manometer is good, you are ready to check if the throttle bodies are in synch.

From here on in, just follow the instructions on your manometer for how to set it up. You have an easy access vacuum bung on each side of the bike for Intake #1 and Intake #2. Here is my CarbTune hooked up to both intakes and a synch test underway

And that's why we do this stuff. To make it easy, to check and know that the bike is correct, not perfect, but correct. If you have to adjust, MotionPro has a 110 degree "air/pilot screw driver" that makes it real easy to adjust Intake #2 to match #1. No removing the gas tank, we made this too easy.

Remember this, we always adjust Intake #2 to match Intake #1 (don't mess/change Intake #1 for synching). Changing the idle rpms on the bike is a different banana.

All for now, I will update if anybody needs more details of what we are about on this mod.

[cornerslider]

I wish I had seen this 2 weeks ago.....  I pulled off the bodywork, and such to synchronize. Next spring, when I do it again, I'm adding this set-up. Absolutely BRILLIANT idea!!!! Thanks for the great write-up. I'm following this post -

[Pursuvant]

that brilliant idea, is all @D.A., but i'm not going to say he's full of it hahaha

[Triple Jim]

I did D.A.'s mod with the short lines as he documented, and have had no unusual results... just easy access to vacuum for syncing.

[DewMan]

I can confirm that long lines to the rear will throw an error from personal experience. 

My assumption was I had leaky hose.

[Pursuvant]

2 hours ago, DewMan said:

I can confirm that long lines to the rear will throw an error from personal experience. 

My assumption was I had leaky hose.

I was interested enough in "proving" it was a vacuum leak had me working this when I could for about 3 days, doing all the usual stuff, I switched out every component, every clamp, every hose piece, epoxy sealant on every connection, ++. 

Then it dawned on me, just take an 18" piece of cheaper Autozone 5/32" vacuum hose, plug one end in sensor and other into intake, and keep the rest away from hot motor. That piece raised the ecu "check engine" light. I took out my pocket knife and cut it to about 8", plugged it back in, and rode bike rest of day with zero problems.

Found this on R6 forum talking about air pressure sensor.

""Measure intake vacuum. Mostly use to tune deceleration and on/off throttle. When I map with the PCV I like to run the Autotune with the psi map for a bit. Smooth things out in the cruising range a lot.""

If the vacuum hose is too long, when you engine brake/decel with throttle closed, you get the "check engine" light for about 1 long second as you engine brake thru 3K rpms. If you hold the throttle ever so slightly open while engine braking, you get no "check engine" light.

It's the sensor, strangely affected, it's measure of pressure drop/change by a long hose on the "Tee", even though the sensor direct hose path from sensor to intake nipple is still present and same length as stock (imo).

 

Edited April 15, 2021 by Pursuvant

[mt7fan]

Interesting mod. But how often is there actually a need for throttle sync? 

[FZWes]

Interesting, confusing as all get out but interesting. Another member of this group posted about the process of T.B. sync and it stirred my curiosity. I have absolutely no knowledge of this process but it is interesting just the same.

[D.A.]

6 hours ago, FZWes said:

...confusing as all get out but interesting.

It’s sounds confusing and somewhat intimidating at first but is actually a very simple concept and procedure.

Your bike has 2 cylinders. For optimal performance, the amount of air and fuel going into cylinder 1 needs to be identical to the amount going into cylinder 2. To achieve that goal, you connect hoses to the two vacuum ports on the throttle (one port corresponds to cylinder 1 and the other, cylinder 2) and use a manometer (which is an amazingly basic device) to measure and compare the amount of suction coming from those ports. If the two levels match, great! They’re in sync. If not, you adjust a screw on the right side of the throttle to increase or decrease the amount of suction until it matches the left side. 

Doing what I just described takes about 10 minutes but the task is complicated by the fact the vacuum ports are annoyingly hard to reach without removing a lot of other parts. To alleviate this issue, @Pursuvant and others have permanently affixed hoses to their vacuum ports and routed those hoses to a readily accessible location, thereby making throttle body syncing an easier job in the future. 

Edited April 25, 2021 by D.A.

[FZWes]

D.A. that sounds relatively simple to do. Like you said getting to the vacuum hoses is  annoying, however the solution offered is great.

Thank you