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Vboost Not Installed

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Hello to all and I am new to this forum and wanted to introduce myself and comment about the wealth of information that I have seen here in the last few days of reading. Great place!. I just purchased a 1985 Vmax that is running but I found that it has an aftermarket device that has a hose that screws into the oil filler cap and runs up below the air box into a canister, then has two small filters coming out of it. The carbs are mounted, and the bike starts but I didn't see the Vmax Vboost system. I went through the parts boxes and found the lower unit that has the butterfly assembly, the control box is still mounted on the left side, but the servo motor is missing. I jumped the gun and bought a complete assembly on eBay. When I plugged the servo into the harness the servo motor didn't cycle through its initial stage, so I am going to test it and the control box this weekend. This is the year, color and the bike that impressed me when I rode it in 1985! I'm 56 now and have always wanted this bike, now I have it. Any help with this setup would be most appreciated as I'm not very sure why this bike has this crankcase breather system on it and why the Vboost was taken off and how it was by-passed. Thanks for listening!
 

rebeltaz83

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Complete aftermarket exhaust from the engine to the mufflers. 4 to 1 will gain the most power, 4 to 2 if you like looks of the duel mufflers. Not just slip ons, which is mufflers only on the oem header pipes, don't usually result in any added power, just noise.
 
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Complete aftermarket exhaust from the engine to the mufflers. 4 to 1 will gain the most power, 4 to 2 if you like looks of the duel mufflers. Not just slip ons, which is mufflers only on the oem header pipes, don't usually result in any added power, just noise.
That's what I thought but not on this bike, I want to take this off and put the Vboost back on.
 

MaxMidnight

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A good start would be to confirm
what, if anything, has been done to the carbs.
Check what jets and needles are fitted, see here.

The different needles below.
upload_2019-12-13_9-12-53.png
 

Traumahawk

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Thanks I will check, the exhaust is stock so I'm wondering what was done here and why the Vboost system was taken off.
In the stage 7 directions dynojet recommends taking the vboost off and putting tubes that come with the kit in place of the vboost butterflies. There have been people in the past that have run a stage 7 kit with vboost and not replaced the butterflies.

But....if you are still running essentially the stock exhaust.....your better off going back to stock on the carb set up with vboost.....or going with an aftermarket exhaust set up. With the aftermarket exhaust you can put vboost back in place and continue to run the stage 7 kit. You might have to do some tuning on the carbs but this forum has all of the answers that you need and has some great tuners on here as well.
 
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In the stage 7 directions dynojet recommends taking the vboost off and putting tubes that come with the kit in place of the vboost butterflies. There have been people in the past that have run a stage 7 kit with vboost and not replaced the butterflies.

But....if you are still running essentially the stock exhaust.....your better off going back to stock on the carb set up with vboost.....or going with an aftermarket exhaust set up. With the aftermarket exhaust you can put vboost back in place and continue to run the stage 7 kit. You might have to do some tuning on the carbs but this forum has all of the answers that you need and has some great tuners on here as well.
 
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Just giving an update, I haven't gotten around to taking pics yet but I think the unit I have installed is an Engine Breather.
 

gentsvmax

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That "breather system" and absence of the Vboost could indicate a stage 7, that's why it was suggested to go through your carbs to see how they are set up.
Who know's, maybe the PO sold the header separately.
 
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That "breather system" and absence of the Vboost could indicate a stage 7, that's why it was suggested to go through your carbs to see how they are set up.
Who know's, maybe the PO sold the header separately.
Is there anyplace on the Internet where pics are posted of this Stage 7 system, All that I'm finding is one's with four K&N filters I don't have these filters only 2 small 1 1/2 inch ones.
 
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Pics will help, are those filter's on two of your four carb's?
I took a few pics of this system, there is a canister between the carbs that forks out to 2 little filters and the hose on the other side goes to the oil filler on the right side of the engine.
 

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MaxMidnight

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If I'm understanding correctly the two filters are part of the engine breather system?
What filtration do you have for the carbs?
 
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If I'm understanding correctly the two filters are part of the engine breather system?
What filtration do you have for the carbs?
I have the standard Vmax airbox. I don't know what aftermarket breather system was installed and to get to it I would have to take off the carbs. If I have to I will to get to the bottom of it...
 

gentsvmax

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It looks like the filtered hose with the 90 deg. fitting on it would be the one that attaches to the bottom of your stock air box after you shorten it, put in a tee fitting in order to plumb in that top hose minus its filter. You have the hose's for a breather system Sean sell's, minus the tee fitting you need.
Search "crank case breather mods" here, you'll get pics and instructions.
Welcome to the forum and Merry Christmas!
 

MaxMidnight

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I suspect what was originally fitted was the Dynojet breather kit.
When I had mine the internals of the air/ oil separator came loose and in the end I made my own.
If that also happened on the one you have that could explain the two mini filters.
What is still a mystery is why was installed.
I would start by pulling one of the throttle slides to see what needles are fitted.
Are the tamper proof screws still in place on the carb tops?
 

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