Different carb set up on VF1000R engine

[GreyVF750F]

I have to think that with those long intake tubes, you will not have much of a bottom end. Plus the response most likely will be slow until you get in to higher 6k or above rpms. Hope you kept the stock setup. You may just need it later.

[donald branscom]

Originally Posted by GreyVF750F

I have to think that with those long intake tubes, you will not have much of a bottom end. Plus the response most likely will be slow until you get in to higher 6k or above rpms. Hope you kept the stock setup. You may just need it later.

I make things happen.
Yes, I have the stock carbs if this plan does not work.
I learned that in the military....always have a 2nd way out.

[donald branscom]

Something I read recently....
"That depends on what your after? Long runner intakes are for the most part better used for low rpm operation, where as short runner intakes are better for high rpm operation. Thats really a super over simplication of the matter.

Intake runners are designed to take advantage of resonant tuning by using a series of pulses which occur in the manifold.
To get a rough idea of where the resonant tuning takes place determine the rpm at which the resonant tuning occurs using the approximations below. then compare them to the runner lengths.for example plug in 6000 rpm for each one

2nd Pulse Length: 108,000/rpm (18 inches)
3rd Pulse Length: 97,000/rpm (16 inches)
4th Pulse Length: 74,000/rpm (12 inches)
5th Pulse Length: 54,000/rpm ( 9 inches)"

[donald branscom]

This looks interesting and very useful.
Now I just have to figure intake areas.
Intake Runner and Peak Torque Calculator
Click on link above.

[donald branscom]

Using the formulas given in the link above this is what I get.

Each intake is about 6 inches to the CYLINDER head.
The area of all 4 intakes is 484 sq. inches.(121 each) 1.625 diameter tubing.
So the peak torque would be at about 2,799 rpm.
The optimum length of intake tract at 6,000 rpm would NEED to be, (including length from carb to intake valve seat -14 inches. and right now the length is about 13 inches total from carb to intake valve seat. Very close, and this puts all the torque at about 5,000 rpm. not bad.

[VF1000RS]

Couple things:

Handling is somewhat more important than maintainence access on a sporting bike, therefore the frame wrapped around the engine. Kinda curious to see how yours will handle.

Cruising speed of the engine? I don`t know. Depends on what you mean by cruising speed. I just got back from a run on my R and anywhere from 5k-7k depending on traffic, with blasts up to the 11k redline, roadspeed around 80 is a good cruising speed for mine.

Looks like an interesting project. I am curious how the intake runners length will affect the fueling. I don`t really have any issues working with the 4 stock carbs, but it`s interesting to see your work. Not much of a chopper fan, but the powerplant you`ve chosen is one of my favorites, and I like well put together machines, no matter what they are.

[donald branscom]

Originally Posted by VF1000RS

Couple things:

Handling is somewhat more important than maintainence access on a sporting bike, therefore the frame wrapped around the engine. Kinda curious to see how yours will handle.

Cruising speed of the engine? I don`t know. Depends on what you mean by cruising speed. I just got back from a run on my R and anywhere from 5k-7k depending on traffic, with blasts up to the 11k redline, roadspeed around 80 is a good cruising speed for mine.

Looks like an interesting project. I am curious how the intake runners length will affect the fueling. I don`t really have any issues working with the 4 stock carbs, but it`s interesting to see your work. Not much of a chopper fan, but the powerplant you`ve chosen is one of my favorites, and I like well put together machines, no matter what they are.

Choppers are all about the looks, the vibe any sport bike will handle way better than a chopper. This frame has 42º rake so at low speeds the handling has to be with care. On the freeway it will just glide along and feel very secure. I used to race motorcycles but this motorcycle is just to putt around on and be relaxed.

[donald branscom]

OK!!!! The offset sprocket from Germany for my VF1000R just arrived and did not seem to get held up in customs. 7mm offset thats .270 thousandths or more than 1/4" but less than 3/8."
Now I can get those engine mounts welded into place.

[GreyVF750F]

Originally Posted by donald branscom

Something I read recently....
"That depends on what your after? Long runner intakes are for the most part better used for low rpm operation, where as short runner intakes are better for high rpm operation. Thats really a super over simplication of the matter.

Where did you ever here this? That's totally backwards from everything I've read and done and experienced. Short runners and or small cross section intakes have a higher velocity in the lower mid rpm ranges. Longer runners work better at higher rpms and can also create a ram effect in some instances. Depending on a lot of shit.

Resonance tuning is a bit more complicated than just using formulas for pipe. You also have wet flow, cross section, velocity, over lap and how straight it is to the valve. Just for starters. You have quite a turn in the intake there. Plus you will not be able to get 100% volumetric efficiency. Not many stock vehicles can come close let alone racing engines. NA of coarse. Pressurized is a totally different animal.

But you'll have a fun time sorting this stuff out. If you really want to get in to this stuff and learn from some of the best engine builders in the US and other parts of the world go here and poke around and ask questions. These guys do it for the love (hehe) and pain of it. This has got to be one of the greatest sites for actually straight info on the web.

Speed Talk

[donald branscom]

Originally Posted by GreyVF750F

Where did you ever here this? That's totally backwards from everything I've read and done and experienced. Short runners and or small cross section intakes have a higher velocity in the lower mid rpm ranges. Longer runners work better at higher rpms and can also create a ram effect in some instances. Depending on a lot of shit.

Resonance tuning is a bit more complicated than just using formulas for pipe. You also have wet flow, cross section, velocity, over lap and how straight it is to the valve. Just for starters. You have quite a turn in the intake there. Plus you will not be able to get 100% volumetric efficiency. Not many stock vehicles can come close let alone racing engines. NA of coarse. Pressurized is a totally different animal.

But you'll have a fun time sorting this stuff out. If you really want to get in to this stuff and learn from some of the best engine builders in the US and other parts of the world go here and poke around and ask questions. These guys do it for the love (hehe) and pain of it. This has got to be one of the greatest sites for actually straight info on the web.

Speed Talk

Thanks for the link to Speed talk.

[Wrencher]

Sorry bud,

A VF1000R Motor in a chopper frame??

Just wrong.... wrong......

[TOE CUTTER]

Got a new Benjamin says he is just fine and will have to lean out the mixture.

[donald branscom]

There are lots of choppers built with metric engines.
Look at this one!