V boost disco questions

[CNN SUCKS DONKEY]

97 VMAX 25K ; Ive read some of the Vboost how to's and My understanding is the Vboost can be disconected in the open position. Questions ; by disconecting does this mean it will always be in vboost mode at any rpm and the bike will always get the vboost benefit at all rpms ? Also does diconecting this way only leave your butterfly flaps only 3/4 open if so is there a way to fully open the flaps ?

 

[Traumahawk]

Well you have to time it just right. The easiest way, is when you listen to the vboost cycle, when it gets to full opening (because during the test cycle that you hear everytime you start the bike, it will fully open, then fully close) wait for it to go fully open, then simply unplug the round connector that is under the left scoop.

Vboost benefits....not so much. Ok, so it will sound great at idle. To sync the carbs, you will still have to close it. Vboost open all the time will make you very lean at part throttle and the bike will definitely be down on power even at full throttle.

Below is a dyno sheet from LVLhead, from where he tested vboost open full time, vs factory setting.

http://vmax.lvlhead.com/tips/tboost.htm

 

[MaxMidnight]

The dyno sheet from Mr Traumahawk shows why it is not a good idea.

To explain why a bit of carb theory.

As the air is pulled through the venturi the air pressure drop and pulls fuel up through the main jet.
The fuel forms very fine droplets (a.k.a. atomisation) which mixes with the air.
The droplets reduce in size the faster the air flows over the main jet.
The finer the droplets the bigger bang you get when it is ignited.

To get good low down torque a smaller venturi (higher air speed) will give better atomisation but as the revs rise there will come a point where the smaller venturi won't allow sufficient air to flow to satisfy the engines requirements.

One alternative would be to fit carbs with a lager venturi but then torque at lower revs would suffer as the lower air speed wouldn't atomise the fuel as effectively.

In other words, venturi size is a compromise between good low down torque or high end power.

Yameringha addressed this issue by using a carb venturi size that gave good low down torque but were able to satisfy the engines requirements at high revs by drawing intake charge from the linked carb.

By keeping the V boost butterflies permanently open you will reduce the air speed, get poorer fuel atomisation thus lower torque.
I suspect this is the red plot on the dyno chart.

You will also loose that surge of power as the V boost cuts in which (IMHO) is addictive.

I don't know what it does to the mixture mid range but don't understand why permanently open V boost would down on power at full throttle. The dyno chart doesn't support that...Mr T?

 

[savage]

My '85 has a Stage 7 jet kit with VBoost delete (no butterflies, no controller or stepper motor, nothing) Also running MegaCycle cams, COPS and K&N pods. Also has a 4-1 Hindle SS header. It sounds like a Pro Stock V-8 at idle up to ~3K RPM where it cleans up nicely.
I also do not see how running the VBoost open all the time can hurt top end horsepower. It does hurt the low end some, but who rides at the low end anyway?:ummm:

 

[[email protected]]

My boost controller doesn't work so, I wired up a toggle switch that allows me to open/close vboost on the fly.

I've played around with it quite a bit while riding.
I leave it wide open most all the time.

Here are my observations based on seat of the pants feel.

Above 6K: No difference at all

Between 2K and 6K: The throttle feels more sensitive to input meaning the bike feels a bit jumpier during a throttle transition from closed to open but as you crank it more, it seems a touch weaker overall.

Between 1K and 2K: Sounds great at idle. Feels almost a touch too lean at times when you pulling into/out of a parking lot. Its not constant but once in a while it will not feel "smooth" is the best way I can describe it. If you've ever been a full clip high on your needle and tried to hold steady throttle, it feels a bit like that but only lasts a second or so and is not consistent.

If I'm stuck in traffic, v-boost goes off. Once I get moving, I open it and leave it open.

I've had the homemade switch installed for a few years now. It works fine and the bike runs fine but I feel that it runs better in stock configuration. I bought an aftermarket boost controller thru Sean awhile back but have yet to install it.

 

[Traumahawk]

I don't know what it does to the mixture mid range but don't understand why permanently open V boost would down on power at full throttle. The dyno chart doesn't support that...Mr T?

Well looking at the dyno sheet hp with full time vboost, vs hp without full time vboost, there is a little bit of a blip on the hp without full time vboost, otherwise the curvature of the graphs is virtually identical. So I actually think the higher hp without the full time vboost would be more of an anomaly, They should be virtually identical.

Well and I shouldve been more specific, down on power at the midrange Midrange is the place that you will be in as your riding around town, etc.

 

[sdt354]

My '85 has a Stage 7 jet kit with VBoost delete (no butterflies, no controller or stepper motor, nothing) Also running MegaCycle cams, COPS and K&N pods. Also has a 4-1 Hindle SS header. It sounds like a Pro Stock V-8 at idle up to ~3K RPM where it cleans up nicely.
I also do not see how running the VBoost open all the time can hurt top end horsepower. It does hurt the low end some, but who rides at the low end anyway?:ummm:

For s stock carb set up and exhaust, I agree with leaving v-boost alone. I agree it leans the mixture. But tuning for open boost, they run great mid range. How quick you bring the slides open, can compensate for the extra air.

 

[Itgoes]

It does hurt the low end some, but who rides at the low end anyway?

Uh.....everybody?

Hurts the midrange a lot actually. Why would you give up all that power from 4K - 6.5K.......to have a cool sounding idle?

 

[sdt354]

Uh.....everybody?

Hurts the midrange a lot actually. Why would you give up all that power from 4K - 6.5K.......to have a cool sounding idle?

It's a matter of opinion. I didn't give up 4- 10k power with open boost.

 

[Itgoes]

It's a matter of opinion. I didn't give up 4- 10k power with open boost.

It's not opinion.....it's a fact that you are sacrificing significant power from 4K to 6.5K (not 10K.....)

 

[CNN SUCKS DONKEY]

Being its mostly stock, Looks like ill leave it be.

 

[sdt354]

Being its mostly stock, Looks like ill leave it be.

That's your best bet. Suspension and brake upgrades are always best done first. The seats on most Gen 1's is really uncomfortable. Lots of ways to spend your hard earned dollars.

 

[MaxMidnight]

That's your best bet. Suspension and brake upgrades are always best done first. The seats on most Gen 1's is really uncomfortable. Lots of ways to spend your hard earned dollars.

Steve's suggestions are spot on...if you want to go faster then get it to handle and stop.
As for the seat this does depend on the shape of your arse and for how long you ride.
Re-profiling and a gel pad insert certainly hepls.

A few ideas as to how you could invest your hard earned on your Max below.

How many changes from OE can you see?

 

[adambweird]

How many changes from OE can you see?

More than i have time to list, lol

 

[[email protected]]

How many changes from OE can you see?

What front calipers are you running? Almost looks like a modified radial caliper

Sent from my SM-G930V using Tapatalk

 

[MaxMidnight]

What front calipers are you running? Almost looks like a modified radial caliper

Sent from my SM-G930V using Tapatalk

ISR Six pots on Braking Wave 320mm rotors and ISR callipers.

And for those whose Mod Monkey just won't go away you may like to try and incorporate this front end.

 

[Traumahawk]

And for those whose Mod Monkey just won't go away you may like to try and incorporate this front end.

Hmmm and I wonder how much that would cost to get it adapted to a Vmax? :biglaugh:

 

[Fire-medic]

Enough to make your wallet cry, cry, cry!



I have an acquaintance here in Ft Lauderdale FL who is a mechanic. He owns his own shop and works on $$$$ cars for well-heeled customers. These are people who have cars worth 7 figures and who pay four figures for a service based-upon an oil change. When your mid-engined Italian exotic uses gallons of synthetic oil, you don't pinch pennies.

This guy also collects motorcycles. I was at the local Ft Lauderdale Ducati dealer one fine day, and the car mechanic for the wealthy clients was there. He was taking delivery of his latest toy, a brand-new Bimota Tesi. I helped him to get it out of the shipping crate, and watched him assemble it, all of-which he documented with pictures. Yes, an honest-to-god Bimota Tesi 500 two-stroke, center-hub steering, brand-new. James Parker's center-hub steering Yamaha GTS 1000 was based on the FZR 1000, the sportbike predecessor to the R1 sportbike. As I recall Captainkyle had one of these that he flipped in a re-sale. The factory called the bike the 'Omega' chassis, because the aluminum fabrication for the chassis resembled the Greek letter, omega.

I'm no mechanical engineer, but I think from my reading that the center-hub design solves a lot of issues with a traditional double-downtube design. A limitation of steering lock seems to be about the only functional issue with the design, though of course, there is aesthetics.

In a famous move, the Bimota factory tried to buy-back all the Tesi's because the bike was released before the engine management technology was finalized, what a blunder. I expect that given the current state of engine management, it wouldn't be an issue today, but I doubt we'll see two-strokes return to the marketplace anytime. Even with direct-injection technology I doubt any current manufacturer is going to bring-back two stroke motorcycles. And yes, I know there are still some two strokes out there, but not with the latest technology.

Hmmm and I wonder how much that would cost to get it adapted to a Vmax? :biglaugh: