|
|
Post by geoff on Dec 4, 2020 17:27:57 GMT
sorry to ask such a basic question; I understand how the choke works from a fuel enrichment perspective - but, although I can read the wiring diagram - I cannot figure out the process by which the choke solenoid is energised when the engine warms up. Can anyone plese help? cheers geoff
|
|
|
|
Post by velocekid2 on Dec 7, 2020 1:19:32 GMT
Hi Geoff, The carburettor auto choke can be explained with a simple analogy. The choke needle can be likened to a retractable ball point pen, spring assisted with a plunger at the top. When cold, the choke needle is in the retracted position (closed) and allows a small additional flow of fuel into the incoming fuel/air charge. Above the choke needle is an enclosed chamber containing a small heating element surrounded by a material most likely to be thermo wax. As the ignition is switched on, a current flows through the heater element, melting the thermo wax. As the wax expands, it forces the choke needle down - like slowly depressing the ballpoint pen plunger down, revealing the ball point writing head. When the choke needle reaches full travel, it cuts off the extra fuel flow, thus closing the choke assistance. When the engine is switched off, so is the current to the heater element and the thermo wax slowly returns to its original state. In turn, the return spring resets the choke needle back to its original position. I don’t claim this to be 100% correct, but I’m happy to be educated! HTH |
|
|
|
Post by geoff on Dec 7, 2020 16:02:21 GMT
that makes very logican sense Phil, thanks.
I was thinking it is a solenoid which received its 'engine is now warm' signal from another place but your proposal is fully logical.
cheers
geoff
|
|
|
|
Post by velocekid2 on Dec 7, 2020 16:53:22 GMT
Geoff,
I wouldn't be surprised if there also may be a thrmosatic device which detects ambient air temperature and overides the heating of the element when the engine is still warm or during warmer days. I've never taken one of these apart.
I still have a 1982 Suzuki 'ped fitted with a Mikuni VM14 carb. Instead of a heating element, a copper heat transfer rod fitted into a recess between the cylinder cooling fins, across to the thermo wax chamber and plunger rod. All old school tech back then, but the principle is the same!
|
|
|
|
Post by geoff on Dec 8, 2020 17:31:13 GMT
no Phil, you were right the first time. This can be observed from looking at the (rather difficult to read) wiring diagram.
p.s. I am tempted by the current 50% reduction Italjet have on the price of the helmet box under the seat - but perhaps I will see how she runs first (we have had a good few cold rainy days recently so no road test yet).
cheers
geoff
|
|
|
|
Post by velocekid2 on Jan 2, 2021 2:18:57 GMT
|
|
|
|
Post by ianmartin40 on Jan 4, 2021 23:03:51 GMT
Excellent tutorials.
cheers
Ian
|
|
