Type of air and or gas intakes

[flw]

I've seen traditional carbs, throttle body gas injection and individual point injection gas injection.

On motorcycles are throttle body or individual point injection really a high single digit increase in preformance or mileage as compared to (upgrade) costs. I'm wondering about the real upside of upgrading a non-racing bike for the fun factor.

With computers today, if its more of a hassle or cost than its worth, unless it came with one.

Also what would be the shade tree mechanics most effective single upgrade without special/unique tools. Or is his day far over?

[TechTMW]

I've seen traditional carbs, throttle body gas injection and individual point injection gas injection.

On motorcycles are throttle body or individual point injection really a high single digit increase in preformance or mileage as compared to (upgrade) costs. I'm wondering about the real upside of upgrading a non-racing bike for the fun factor.

With computers today, if its more of a hassle or cost than its worth, unless it came with one.

Also what would be the shade tree mechanics most effective single upgrade without special/unique tools. Or is his day far over?

I was confused when I first read this LOL... Use "Fuel" instead of "Gas"

You are missing a few locations for injectors (Like the showerheads in the airboxes of some bikes) but that's probably not relevant to this discussion.

Manufacturers have added fuel injection for many reasons. The biggest reason is probably environmental. Fuel Injection systems constantly change the fuel output based upon Amount of air entering the engine, environmental factors like altitude, and operating temps. This means that the bike is consuming only the fuel that it needs to deliver good performance = better fuel economy, and less pollution.

Open-Loop (uses an o2 sensor) fuel injection is also self-tuning, which means that it keeps the bike runnin economically without any user imput. This isn't the case on a carbed bike. To get the optimal state of tune on a carbed bike, you'd have to at least get an exhaust gas analyzer - if you want optimal tune and performance, you'd need a full-blown dynamometer. Therefore, many carbed bikes are WAY out of tune, and the owners haven't really got a way to correct the faults, since these tools aren't available to most people.

Another performance aspect of fuel injection is that it is easily programmable by computer. You don't have to fiddle with jets and floats and needles to change the way fuel is delivered to the engine. You simply have to plug up a few wires and tweak the computer for proper fuel flow for the application.

Adding fuel injection to a carbed bike is possible. Some bikes that have a major cult following (Like BMW Airheads) have ready-made bolt on fuel injection in the aftermarket. There are also ready-made computers available for fuel injection for any application. You'd also have to determine what kind of runners you need, and what kind of injectors to use, etc... Depending on the bike, it is also possible to retrofit fuel injection systems onto a carbed bike, from the newer models, with a little bit of imagination.

But, unless you have the ability to program a fuel curve, and can determine proper runner lengths and fuel flow rates for your bike, cobbling together a fuel injection system is a really iffy proposition, and the benefits are rarely seen without a proper setup. Often, the bike will run alot worse than it did with the old carbs.

My Opinion on the shade-tree mechanic's best performance upgrade ? A high-quality suspension. Your Suspension and tires control your ability to keep your rear off the pavement. Too often people make all the upgrades to their power output without paying any attention to the way the bike handles. It can have disastrous consequences, especially on older bikes with ragged out suspensions. If you are looking for more power, there is also the tried and true method of freer flowing intake, bigger jets, and freer flowing exhaust.

[flw]

Your right there's much I don't know, so I ask to learn from people like you and your excellant explanation.

Great Job.

[mydlyfkryzis]

Open-Loop (uses an o2 sensor) fuel injection is also self-tuning, which means that it keeps the bike runnin economically without any user imput.

I think you meant closed loop. Open loop does not need an O2 sensor. No feedback from the result of combustion (hence open loop). The open loop relies on RPM and throttle position and manifold vacuum and injects fuel from a fixed map. The air mass may be guessed at (throttle position only with manifold vacuum), or less guessing with an air volume sensor (usually a paddle type device in the air stream) or a hot wire sensor (The air movong past the wire cools it and changes resistance depending on the mass of air moving past it).

Closed Loop is similar, except is also uses the O2 sensor as a feedback. if too little O2 (rich) or Too much O2 (Lean) is in the exhaust, it adjusts the map at that point to bring the mixture back into the desired O2/Fuel ratio.

Most closed loop systems start up on open loop and are also usually on open loop at WOT. At WOT they usually keep the mixture slightly rich to avoid detonation. The extra fuel tends to cool the combustion down with the extra fuel.

[TechTMW]

I think you meant closed loop.

Sure Did! Thanks