Equalizing Vacuum

[06VMAXIMUS]

Somebody needs to put spyder in for the "mod monkey" award!!! Great mod!!

 

[dannymax]

Somebody needs to put spyder in for the "mod monkey" award!!! Great mod!!

I agree 100%....IT'S DONE!!

 

[44 magnum]

SHIT ! .....THIS MEANS I'M GOING TO HAVE TO DO IT !:bang head:

It won't take that long Bubbs and you already know it's not expensive. I'm very glad I did mine as others have stated, so I'm guessing you'll be happy with it too.

I think Chris asked about fuel econ numbers... After the mod, mine's unchanged.
(Oh and I have a stock set up so I can't comment on the open v-boost question.)

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[GREEN light BLITZ]

Dave told me about this thread :You_Rock:,I read it and weighed everyones opinions and theories and figured this has gotta work!The answer is yes...IT WORKS.I have the V-Boost over ridden on my Max.That being said:Starting seemed the same maybe a LITTLE bit easier but not enough to call it without trying it a bit more.My low end felt the same,not much better but I also didnt give the bike much time to warm up(wich makes a big difference in mine at least)I think while warm the low end will kick a little harder.WHERE IM MOST impressed is mid range and idle:ryb:.My idle is smooth and clean and my bike SOUNDS more aggressive on take off.The lope of the V-Max stock can be mistaken by some for a miss or somthing like that,this smooths it out and makes it a nice low rumble instead of a spiking lope sound.So in technical terms now its more of a "plub,plub,plub,plub,plub" Intead of "BLIKITY,pop,pop,pop...BLIKITY,pop,pop,pop" :lol_hitting:Technical I KNOW! And on that note the mid range increase is what had me smiling in my helmet and giggling about how FOR ONCE a $6 mod worked and really made a feelable difference.I say do it.If you dont like it,it takes 10 minutes to reverse,what do you have to lose?

 

[forestdaledave]

I'm going to do this . I have a switch that allows me to choose open or normal vboost. I'm looking for better off idle response with open vboost. I will chime in after I done it.
Dave #3505

 

[dannymax]

I don't even pretend to understand this mod but we were talking with a guy at the 'Ricer' who said he was the person who thought up this mod about 15 years ago and posted it to the Venture Forum.

He said the proper way to do the mod is to link the right side carbs together and the left side carbs together but not to link the sides together. In other words, link #1 with #2 then $3 with #4, that's it, nothing else. I did this, don't really see any difference, but it makes a nice neat installation.

danny

 

[gamorg02]

I'm going to do this . I have a switch that allows me to choose open or normal vboost. I'm looking for better off idle response with open vboost. I will chime in after I done it.
Dave #3505

yea let me know dave, thats what i go back and forth between. are you able to share your switch schematics? i've been looking for one to do this.

 

[44 magnum]

He said the proper way to do the mod is to link the right side carbs together and the left side carbs together but not to link the sides together. In other words, link #1 with #2 then $3 with #4, that's it, nothing else. I did this, don't really see any difference, but it makes a nice neat installation.

danny

But then both sides need to be hooked into the Vac Advance, no? That's how I did mine.


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[dannymax]

But then both sides need to be hooked into the Vac Advance, no? That's how I did mine.


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That's how I did mine at first too, but he said just #1 & #2 should be tied to the vacuum advance.

I re-did mine yesterday per his suggestion and it really seems about the same as when all 4 were linked together.

 

[tugla]

hooked mine up with all four eventually to the advance and dont really feel anything different in the bike. starts the same runs the same, haven't done a fuel mileage test yet. the only thing that did chg was the slight part throttle or just off idle, either from a stop or slow driving, its not as responsive anymore, dont like it, almost feels like a dead spot and need to get it up a few hundred rpm to feel normal again. might just take it off and run it original way, seemed better. guess its helping guys when they have a little carb issue, smooths it out. Like to know what Sean thinks of the mod? has anyone dyno'd their bikes with the mod ???

 

[naughtyG]

I did it on mine, and noticed zero difference, none, zilch, nothing.

So a few days ago I removed it and went back to #2 to vacuum, #1, 3 & 4 capped.

Bike runs great - no difference. I may try that 'proper' way Dan-o's talking about at some point just 'cos I'm curious =

 

[ninjaneer]

Great sound Ninj....congrats on the install, looks terrific. Have you tried the vacum mod? Gives it a mean nasty idle!!

Captured the following entries from my exhaust thread that went off topic. The information is more useful here.

It's really cheap, but don't tie all them together....ONLY tie #1 with #2 then tie #3 with #4....that's it....don't link the sides together.

For the vac advance on #2 just use a 'Y' fitting link #1 & #2 together and use the 3rd leg for the advance.

Wouldn't this be about the same thing, but less agressive due to the smaller tubing, than having the vboost open at all times??? Is this just am milder form of doing that?

I went back and read that thread that was posted, having entirely missed it before. I do not see how it can possibly smooth out the idle as some claim. At least not when knowing that opening the Vboost requires turning the idle stop screw adjustment to get the idle back up to where it will run at all. I can see where it might make it start easier but not sure why??

Opening the vboost full time most definitely gives it a nasty sounding idle, I have my butterflies and the cable still in place with a cable stop screw on it so it can be closed for synching and left open all other times, i removed the servo motor and controller all together.
This can also be done by simply locating the round connector behind the left scoop and unplugging it during the middle of the power up cycle on the vboost when turning the key on if you want to try it without modifying anything.
Pulling it open gives it a fantastic sounding idle, and has resulted in Zero ill effects except at maybe 2000rpm or less, I run an a/f gauge and have proven that the myth about opening it full time makes it rich is a myth. The a/f never changes, gas mileage didn't change, and midrange and up performance is marginally better, the low end response thing doesn't bother me at all, I don't race people from 2000rpm anyway; I downshift and run the revs up to where it's making power first.

Now that you mention it Rusty, I think it would be similar to having the boost valving open full time....just....above the carb boots instead of below. I never thought of that....good call!

I certainly didn't notice any smoother idle with this mod, just the opposite....altho, it may smooth out if you tie the left side carbs with the right side (the way the mod was first described).

I believe this vacum linking mod originated on a Venture forum, I met the guy who says it was his idea and that's where he said it started. He explained the whole thing to me, theory included, but we were at the Rice-o-Rama and there was a shitload of noise around and I only heard about 1/10th of what he said.....unfortunately!

see when garrett talks people start to hate the MM again. i still see the connection man dosent anyone else

i tried that vacume mod on one bike and didnt see any change in start up, idle,running,throttle, if anything the throttle response was off a little, or not to my liking so took it off and all back to normal and happyness. i think it all depends on the bike and its setup/tune in the carb. mine is all stock and runs like a champ so maybe thats why i didnt see any difference but others for sure like it...... what ever floats your boat i guess......

yea. awful similar to vboost always on.. only thing that might make sense to tie 1 and 2 together when running vboost always on. since thats more indicative of the pull? maybe not as it would double.

 

[Diablotin]

Thanks for those who messed up ur thread man lol and tnx to you for reposting.
I didnt see the thread before...
Why when reading I'm not feeling that it works really well? some did still keep the mod? which setup?

tnx

Michael

Sent from my GT-I9100 using Tapatalk

 

[dannymax]

I think the earlier posts were describing the mod with the left & right sides tied together. It seemed with my '99 that eliminating the crossover tube and installing COP's resulted in a nearly instant starting and a cool sounding idle. Performance wise I don't believe there was any gain....altho the bike did dyno at 117.1 in that config. so, who knows? :confused2:

 

[RaWarrior]

I just completed this mod for a grand total of $1.64, the price of one tee fitting at the tractor supply down the street. I had some Tygon 3603 tubing lying around that I recycled into this...general purpose lab tubing. Resistant to everything. And it happened to be 3/16 id, which fits on the nipples perfectly.

Idle does seem a bit smoother and more even. I did it Dan-o's way and linked the right two, then teed the left two into the vacuum advance line. The H-covers fit back on without problem.

It's a little cold for a ride here, just ran it on the centerstand. Even at 20* and not been started in a good 3 mo, it fired after maybe 3 or 4 revolutions. Once it ran for 10-15 min, like Dan said it would now restart instantly, first compression and it's running. Not saying it was at all difficult or finicky to start before, but it's even better.

I kept the original line from the sensor down, but pulled out and ditched the little one way restrictor check valve thingy. The arrow and tiny-hole end faced the sensor, with a bigger opening toward the manifold. I tried sucking through it, and got barely any air whatsoever, I blew the other way and something popped and now it's much free-er flowing, so I'm not sure if it was plugged or stuck or what, but it's out of the line, I just replaced it with a coupler to my tubing. On the right side link, it looked like it was tossing gas mist back and forth with the pulses, on the left side some gas dribbling was noticeable near the fittings edges. Not sure if that's just gonna happen, or because it's cold out, or what. Didn't seem to hurt anything.

The idle speed was unchanged, once warmed up it was sitting steady at 1000rpm just like always, but the exhaust note seemed more rythymic and even. Can't really comment on throttle response w/o driving it, but it seemed snappy as ever in neutral at least.

 

[dannymax]

And gentlemen.....that's the 'proper' way to do the vacum mod!

Nice neat job RA!! :clapping:

 

[ninjaneer]

So I finally got around to doing this mod. Cost me a whole $3 for a foot of tubing and the T and I connectors and 10 minutes of garage time....and I suppose you could factor in the gallon of gas and forty-five minutes driving to the local hardware store and back.

M M MMM!. I'm loving this mod. With this mod, my idling bike now has more of a long, drawn-out growl like that of what a Rotty would make when it's en gaurde; no longer the loping rumble you hear when you press your ear up against a purring lion. The jury is still out on this one for me, though. It certainly does smooth out the idle and coming off of idle has softened up a bit, almost too buttery. I've definitely got some jetting issues to deal with now that I've got the Mark's on, so I'll reserve judgment on performance. I took the bike for a spin around the block. Wasn't really dressed for the weather, so didn't tear down the neighborhood. Interesting enough, though, I was sitting in the garage after the test ride watching the tach. For a few seconds, the needle would sit on 1K and then pop up to like 1.2 for a few seconds, drop down to 1K for a few seconds, and then pop back up. No periodicity, no frequency, just "randomly" pop up and down. Mind you it's rock solid at whatever rpm it decides to idle at. the garage starts resonating whenever it idles at 1.2. For now, it's a keeper for me.

Here are a couple pics of my variation on the tubing. I extended the vacuum advance line with an inline barb and a short piece of 3/16" ID, pushed it through the middle of the carb rack, pulled it out between the #1 and #2 diaphragm covers and attached it the trunk of a T-connector that sits just in front of the synch screw. Off of the T, I attached a couple of pieces of tubing and routed them behind the "fuel bowl drain tubes" holder and onto the synch ports. You hardly notice it with the naked eye and I'll bet that unless I point it out to the untrained eye, no one is the wiser. For the #3 and #4 ports, I simply routed the tube from one, up and over the fuel bowl drain lines, and down onto the other. Not saying mine's any better--many ways to skin this cat. This just made it easier for me to screw on the covers.

 

[bazwell]

I'm glad this thread got dug up. Sounds really interesting!

Now, just because I like talking....
If theres anyone without COP's with this mod, there is something that you could try and see. Don't know if it is very possible, just thinking out loud.

I think it would be possible to hook a timing light up to no.1 cyl, pop out the plug on the LHS cover that has the timing mark behind it, and run the bike at idle without too much mess.

The comparison would be to look at how even or clear the flywheel looks at idle between having advance connected to just no.2 and both 1 + 2.

If no-one does it, I might give it a go when I get mine running. I am suffering from some lack of parts at the moment and things have ground to a halt though. I hate delays. :bang head:

 

[dannymax]

So I finally got around to doing this mod. Cost me a whole $3 for a foot of tubing and the T and I connectors and 10 minutes of garage time....and I suppose you could factor in the gallon of gas and forty-five minutes driving to the local hardware store and back.

M M MMM!. I'm loving this mod. With this mod, my idling bike now has more of a long, drawn-out growl like that of what a Rotty would make when it's en gaurde; no longer the loping rumble you hear when you press your ear up against a purring lion. The jury is still out on this one for me, though. It certainly does smooth out the idle and coming off of idle has softened up a bit, almost too buttery. I've definitely got some jetting issues to deal with now that I've got the Mark's on, so I'll reserve judgment on performance. I took the bike for a spin around the block. Wasn't really dressed for the weather, so didn't tear down the neighborhood. Interesting enough, though, I was sitting in the garage after the test ride watching the tach. For a few seconds, the needle would sit on 1K and then pop up to like 1.2 for a few seconds, drop down to 1K for a few seconds, and then pop back up. No periodicity, no frequency, just "randomly" pop up and down. Mind you it's rock solid at whatever rpm it decides to idle at. the garage starts resonating whenever it idles at 1.2. For now, it's a keeper for me.

Here are a couple pics of my variation on the tubing. I extended the vacuum advance line with an inline barb and a short piece of 3/16" ID, pushed it through the middle of the carb rack, pulled it out between the #1 and #2 diaphragm covers and attached it the trunk of a T-connector that sits just in front of the synch screw. Off of the T, I attached a couple of pieces of tubing and routed them behind the "fuel bowl drain tubes" holder and onto the synch ports. You hardly notice it with the naked eye and I'll bet that unless I point it out to the untrained eye, no one is the wiser. For the #3 and #4 ports, I simply routed the tube from one, up and over the fuel bowl drain lines, and down onto the other. Not saying mine's any better--many ways to skin this cat. This just made it easier for me to screw on the covers.

Did you do any shimming, (maybe in the neighborhood of 1mm?)....A/F screws like to be out about 3 1/4 also.

 

[gamorg02]

one thing to keep in mind, if you're using clear tubing it gets pretty 'gassy' coloured after a few rides. if its being covered no worries otherwise just something to keep in mind.