Powerbands.

[Skier]

I have seen "throttle body injectors" made by Ford which were pretty much an attempt to use one fuel injector for all the cylinders by mounting one in a modified carburetor. The injector simply metered the fuel and acted as the main jet.

Throttle body injection was a fairly popular method of cheaply converting the standard intake manifolds used back in the 70s and early 80s to fuel injection. They had some horrible downfalls, like neighboring cylinders not getting the same amount of fuel, and no easy way to solve them. Chevy had their TBI motors (throttle body injection), as well.

The problems were solved by mounting injectors in the intake runners so fuel could be metered per cylinder with magnitudes of power more accuracy. More performance could be eeked out of that design by direct port injection, where fuel is injected much closer into the combustion chamber. This makes the air/fuel mixing happen inside the chamber versus in the runners. The injected runners, or "wet runners," didn't seem to stay around for all that long and I don't think they are in many, if any, cars nowadays.

Hmm, my car gear-head origins are showing again...

[BuzZz]

After checking with BMW, they advised that I take two for the launching as the K1200S is so bloody heavy. Please may I have discount.

For you, Man, no problem.

2 fer 1 sound O.K.? I'll even let you do payments.

[jmillheiser]

throttle body injection is about the simplest injection system there is.

the injector sits above a simple throttle butterfly and sprays fuel into the throttle body. Most use 1 or two injectors though I have seen a few use 4.

My old S-10 blazer had a TBI system that had 2 injectors and a 2 barrel throttle body. Nowhere near as good as a port injection system but still way better than a carb. The TBI systems that popped up in the 80s were a good alternative to carbs, but pale compared to a modern port system.

BTW that wet intake runners of the TBI engines worked just fine, after the throttle body everything worked the same as a carbed engine.

If your wondering exactly how a carb works. the venturi (narrowed down opening in the carb body) creates a vacum in the carb throat that literally pulls the fuel out of the float bowls through the jets and into the intake manifold, incredibly simple but not very precise. Part of the reason why carbed engines with big lumpy cams have a rough idle is the big cam reduces the vacum going through the carb at low rpms which causes erratic combustion, once the cam is in its operating RPM range (i.e. on the cam), the vacum signal becomes very strong pulling lots of air through the carb and hopefully more fuel if the jetting is correct.

[Shiv]

If your wondering exactly how a carb works. the venturi (narrowed down opening in the carb body) creates a vacum in the carb throat that literally pulls the fuel out of the float bowls through the jets and into the intake manifold, incredibly simple but not very precise. Part of the reason why carbed engines with big lumpy cams have a rough idle is the big cam reduces the vacum going through the carb at low rpms which causes erratic combustion, once the cam is in its operating RPM range (i.e. on the cam), the vacum signal becomes very strong pulling lots of air through the carb and hopefully more fuel if the jetting is correct.

Actually I had this discussion on another forum earlier this week and guessed at how it worked.

Looks as if I guessed correctly. My knowledge of physics (basic as it is) triumphs once again.

[sapaul]

After checking with BMW, they advised that I take two for the launching as the K1200S is so bloody heavy. Please may I have discount.

For you, Man, no problem.

2 fer 1 sound O.K.? I'll even let you do payments.

Thanks, and I collect from the second house from the right, right.

[BuzZz]

I figure anyone who rides a 'sport' bike heavy enough to need 2 of these things deserves a break. You buy the airline ticket and I'll hand deliver them, how's that for a screamin' deal, eh?

I'm surprised the Teutonic engineers you talked to would allow such a powerful device to be fitted to one of their bikes, much less 2 of them. The heat from the air friction could be enough to actually round off a corner or 3 on your bike. That would mess up their orderly and right angled vision of a motorcycle, wouldn't it?

[sapaul]

UH Ya yawol

[Venarius]

Yah you got the powerband right,

The steadier the slope from the dyno read, the more predictible the power delivery is to the rear wheel...which makes the bike a better bike for a begginer.

Different Engine designs also have different power bands.

Many think V twins tend to have the most usable powerband, because most of the power delivery is early in the range (usually well under 5000 rpm). This means at any given time on the road, you can have the power you want quickly delivered to you in a smooth manner. (As in if I'm on a big cruiser that lulls around at 2500, and the peak power is 3500, I'm gonna get there a lot quicker vs a inline 4 sport bike where the power is generated up around 11,000 and I'm cruising around town at 7000)

But thats not to say that inline 4's are "hard to handle" or have some crazy "uncontrollable or readable" powerband. My first bike was a inline 4 1981 CB-750. That bike had a great powerband and I had no problems learning to use it properly.

I guess the biggest concern isn't the powerband itself, but rather the total delievery of power. You can have a great bike with a flat powerband, but if its got 200hp and 150 foot/pounds of torque, if you grab a big handfull of throttle chances are a newer rider wouldn't be ready for the resulting jolt.

For a starter, I would look for a bike with no higher than 80hp and 40 or so foot/pounds. That way, regardless of power band you will have a usable yet forgivable ride.

Even with those numbers though you should still be careful and exorcise caution.

Others will disagree. But thats my 2 cents.