Graves Velocity Stack Kit

I have these. But I installed them last winter when I did a bunch of stuff, so can't report how much butt dyno improvement with just these alone. However, my bike runs excellent and Ivan pointed out that the multi sized stacks work better over all that those of the same length.

Graves is mostly a racing company.
 
scout said:
I have these. But I installed them last winter when I did a bunch of stuff, so can't report how much butt dyno improvement with just these alone. However, my bike runs excellent and Ivan pointed out that the multi sized stacks work better over all that those of the same length.

Graves is mostly a racing company.
Click to expand...
thanks scout,
i am new, what is "dyno"?
 
Really? Ivan's been telling me they're kind of a waste of money...:eyebrow:
I'm just surprised because I'm thinking of getting them myself, but if they really don't do much, then I won't...hmmmm...




scout said:
I have these. But I installed them last winter when I did a bunch of stuff, so can't report how much butt dyno improvement with just these alone. However, my bike runs excellent and Ivan pointed out that the multi sized stacks work better over all that those of the same length.

Graves is mostly a racing company.
Click to expand...
 
troyw said:
Really? Ivan's been telling me they're kind of a waste of money...:eyebrow:
I'm just surprised because I'm thinking of getting them myself, but if they really don't do much, then I won't...hmmmm...
Click to expand...

His last post thought the graves best because of the variation in stack lengths, if I recall right.

That's why I went with graves, as the other stacks looked just like the stock. Why mod if like stock, ya know?

'butt' dyno is how the bike feels during a ride. This is funny. Last year I had to stop jogging for awhile because of a knee injury. I didn't want to gain weight, so I kinda stopped eating stupid for a few weeks.

I ride everyday, so don't pick up on what the bike is doing unless really different. So, one day I'm thinking, 'what kinda fuel did I put into this thing as it's like on steroids.'

Kept thinking about it. Then I thought, crap, pants are way loose, wonder if I've lost weight. Go home, went from 190 to 175. Butt dyno noticed that before I did!
 
scout said:
I have these. But I installed them last winter when I did a bunch of stuff, so can't report how much butt dyno improvement with just these alone. However, my bike runs excellent and Ivan pointed out that the multi sized stacks work better over all that those of the same length.

Graves is mostly a racing company.
Click to expand...

This reminds me of when I used to work on carburetors. Velocity stacks work, period.

The longer the intake tract, the more velocity achieved earlier, the more power at lower RPM. The shorter the intake tract, the more velocity achieved later, the more power at higher RPM. This is true when compared to a gun (or garden hose for you greenies), the longer the muzzle the higher the velocity the higher the exit speed.

Many manufacturers have used electronically controlled variable length intake tract for years. On race bikes the intake tract is lengthened with velocity stacks connected to a solenoid that moves them up or down depending on RPM. Yamaha could not do this on the FZ1 and still keep it within the cost guidelines.

An alternative would be to have a different length velocity stack on each sequential cylinder. This way you have two cylinders tuned for low RPM and two tuned for high RPM. This broadens the powerband.

If you look at Graves dyno figures, there is a power gain to behold in the meat of the RPM range that we enjoy on the street.

Let’s look at this economically. $149.95 divided by 5.5hp (average) equals 30 percent gain per dollar spent. Not bad. This puts that $500 you spent on an exhaust to shame!

This is my 2 sense on the subject.

Steve

:fencers:
 
best explanation yet!

FastRnu2 said:
This reminds me of when I used to work on carburetors. Velocity stacks work, period.

The longer the intake tract, the more velocity achieved earlier, the more power at lower RPM. The shorter the intake tract, the more velocity achieved later, the more power at higher RPM. This is true when compared to a gun (or garden hose for you greenies), the longer the muzzle the higher the velocity the higher the exit speed.

Many manufacturers have used electronically controlled variable length intake tract for years. On race bikes the intake tract is lengthened with velocity stacks connected to a solenoid that moves them up or down depending on RPM. Yamaha could not do this on the FZ1 and still keep it within the cost guidelines.

An alternative would be to have a different length velocity stack on each sequential cylinder. This way you have two cylinders tuned for low RPM and two tuned for high RPM. This broadens the powerband.

If you look at Graves dyno figures, there is a power gain to behold in the meat of the RPM range that we enjoy on the street.

Let’s look at this economically. $149.95 divided by 5.5hp (average) equals 30 percent gain per dollar spent. Not bad. This puts that $500 you spent on an exhaust to shame!

This is my 2 sense on the subject.

Steve

:fencers:
Click to expand...

Thanks for the explanation. It is the most comprehensive and understandable to the "Common Man" that I have heard yet. I did wonder about the differing lengths for the center 2 cylinders but your explanation makes sense considering the firing sequence. :deal:
 
Yes Steve. Thanks from me as well. I'd never heard it put that way and now it makes perfect sense.

Now to pry that money out of the account without the "accountant" knowing..... :eek: :D
 
FastRnu2 said:
This reminds me of when I used to work on carburetors. Velocity stacks work, period.

The longer the intake tract, the more velocity achieved earlier, the more power at lower RPM. The shorter the intake tract, the more velocity achieved later, the more power at higher RPM. This is true when compared to a gun (or garden hose for you greenies), the longer the muzzle the higher the velocity the higher the exit speed.

Many manufacturers have used electronically controlled variable length intake tract for years. On race bikes the intake tract is lengthened with velocity stacks connected to a solenoid that moves them up or down depending on RPM. Yamaha could not do this on the FZ1 and still keep it within the cost guidelines.

An alternative would be to have a different length velocity stack on each sequential cylinder. This way you have two cylinders tuned for low RPM and two tuned for high RPM. This broadens the powerband.

If you look at Graves dyno figures, there is a power gain to behold in the meat of the RPM range that we enjoy on the street.

Let’s look at this economically. $149.95 divided by 5.5hp (average) equals 30 percent gain per dollar spent. Not bad. This puts that $500 you spent on an exhaust to shame!

This is my 2 sense on the subject.

Steve

:fencers:
Click to expand...

yeah, this is exactly what Ivan said, except you framed it better.
 
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