Choke switch

[turbine_2]

So, I've a new R1150GS, which has electronic fuel injection and all that jazz. The fuel injection system takes readings from sensors all over the place and deicdes the correct amount of fuel to inject.

So, what is the choke switch for?

My experience of chokes are that they work on the carb but an FI system doesn't have a carb.

Confused of West Sussex.

 

[Roge]

I suspect in reality it is only a fast idle rather than a choke

Roger

 

[Iain Hogg]

So, what is the choke switch for?

Cruise Control

 

[BiG DoM]

I suspect in reality it is only a fast idle rather than a choke

Roger

Suspicion confirmed - merely a throttle advance.

 

[turbine_2]

Hmm, in that case, why is it needed? Surely the EFI system should take care of setting the idle / advance etc.

None of the cars I know with EFI have a choke and nor does my Blackbird.

David

 

[Iain Hogg]

I've only had to use mine if I've started a cold engine, riddenm less than a mile, stopped at cash point, then cold bike won't restart with hot sensor

Touch of "choke" and away she/he goes.

Iain

 

[Dave Barrett]

Hmm, in that case, why is it needed? Surely the EFI system should take care of setting the idle / advance etc.

None of the cars I know with EFI have a choke and nor does my Blackbird.

David

The EFI system does look after the idle, but the problem with all systems during cold idle is that the throttle(s) must be slightly open to provide sufficient air to match the quantity of fuel injected. On inline engines, the throttles are linked together, normally with a rod that actuates the throttles together. During cold conditions, a wax-operated or similar device slightly opens the throttle assembly (by acting somewhere on the rod) to provide the correct air amount.

The reason that an external device is needed on BMW's is the Boxer configuration, where the two throttle are cable operated, rather than linked by a solid assembly. This means that to use the above system, two separate devices would be required (one for each throttle), and then there would be a risk that the throttles are not opened to the exactly the same amount, mening the throttle balance when cold would not be correct, providing a very unstable idle.

Therefore, the simple option is to use a manually operated cable set-up, which is also easy to balance.

 

[turbine_2]

Dave, thanks for that explination. That makes a lot more sense to me now.

David