Direct fuel injection and why it is not used on motorcycle engines

You might find this subject interesting: This article explains what direct injection is and why it is not used on motorcycle engines (yet): https://www.motorcycle.com/ask-mo-anythi...otorcycles.html

I thought my XX had direct fuel injection, but schematics indicate it was an injector at each cylinder injecting into the intake flow and not the cylinder.

I don't think it ever will be. This is lifted straight from Wikipedia:

"The ability to produce peak power at high engine speeds (RPM) is more limited for GDI, since there is a shorter period of time available to inject the required quantity of fuel. In manifold injection (as well as carburetors and throttle-body fuel injection), fuel can be added to the intake air mixture at any time. However a GDI engine is limited to injecting fuel during the intake and compression phases. This becomes a restriction at high engine speeds (RPM), when the duration of each combustion cycle is shorter."

I've had a direct injection petrol car; never again.

Cheers

Paul B.

Zitat von Paul B im Beitrag #3

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I don't think it ever will be. This is lifted straight from Wikipedia:

"The ability to produce peak power at high engine speeds (RPM) is more limited for GDI, since there is a shorter period of time available to inject the required quantity of fuel. In manifold injection (as well as carburetors and throttle-body fuel injection), fuel can be added to the intake air mixture at any time. However a GDI engine is limited to injecting fuel during the intake and compression phases. This becomes a restriction at high engine speeds (RPM), when the duration of each combustion cycle is shorter."

I've had a direct injection petrol car; never again.

Cheers

Paul B.

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Zitat von duccrazydave im Beitrag #4

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On cars with only GDI (and not additional port fuel injectors) there are, apparently, eventual problems with deposits building up on the valves. What issues did you have with your GDI car?

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Zitat von Paul911 im Beitrag #5

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The issue with direct injection is that the PCV system puts gases from the crankcase, which include oil vapors, back into the intake. The oil vapors mean that carbon builds up on the intake valves because there's no solvent (fuel) to wash them away.

Do any motorcycles have PCV systems like this?

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Zitat von Duckbubbles im Beitrag #6

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Zitat von Paul911 im Beitrag #5

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The issue with direct injection is that the PCV system puts gases from the crankcase, which include oil vapors, back into the intake. The oil vapors mean that carbon builds up on the intake valves because there's no solvent (fuel) to wash them away.

Do any motorcycles have PCV systems like this?

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I would suspect that practically ALL modern motorcycles have a variation of this type of PVC system incorporated. I remember seeing crankcase to airbox breathers back in the 70's.

Frank

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My '92 Ducati had a similar system. Hose from the crankcase to a separator box, then to the airbox. Removed mine years ago

Zitat von Duckbubbles im Beitrag #6

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Zitat von Paul911 im Beitrag #5

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The issue with direct injection is that the PCV system puts gases from the crankcase, which include oil vapors, back into the intake. The oil vapors mean that carbon builds up on the intake valves because there's no solvent (fuel) to wash them away.

Do any motorcycles have PCV systems like this?

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I would suspect that practically ALL modern motorcycles have a variation of this type of PVC system incorporated. I remember seeing crankcase to airbox breathers back in the 70's.

Frank

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