The Honda PCX / Forza / ADV150 / SH Forums

How does the PCX start? Did I hear correctly that the PCX doesn't have a separate starter? That it uses an alternator somehow to start?

The 2015 model I have is equipped with the idle stop feature. When I stop for 5 seconds (like at a light) the engines stops. It immediately goes again when I twist the gas. I know models in different countries don't always have this feature. I can switch this off. It works like a golf cart where you just twist and go, with no waiting for it to start. Bang, you're off. I'm wondering how that works?

Sorry for asking this in a clumsy manner.

Portuguese I don't know, but the images are telling. PCX doesn't need a starter because they wind the crankshaft somehow and use an ECM (brain) to tell it when to energize. It looks like you are sitting on the compression stroke waiting to fire the plug when you throttle. I always wondered if you wait too long do you lose the mixture
Idle stop swing back is what these guys are calling it but I don't think that's current branding.

again.. https://www.youtube.com/watch?v=T444xQer8HA

The alternator is also the starter motor.
When the idle stop cuts the engine, a crankshaft position sensor tells the ecu where the crankshaft is, the alternator engages motor mode and the ecu places the crank in the optimum position for starting.
This is what Honda call Swingback.
Google honda swingback for more info.
When the throttle is opened the starter turns the engine and because the crankshaft is swung back in the optimum position it fires almost immediately, roughly three tenths of a second.

Its a promotional video for a Brazilian Honda dealership, only the first half is about the PCX. He says that the engine cuts out after 3 seconds, then the alternator works as an electric engine and positions the piston in the best position. Interesting is the part when he says that the start isn´t immediate after yanking the throttle, but that the exhaust valve stays open for a while even if the piston turns around so that with the next fuel injection cycle the combustion is clean and ignites with the next spark, but that cycle is so quick that we believe its immediate.

Sure feels immediate and no lag to start. I'm happy to put it on idle stop and do a hard start at the lights yet not feel like I've got any lag from the time I wait the throttle to the time the bike moves

I agree it seems instantaneous and I always use the start-stop even in rush hour traffic no worries.

The alternator is a brushless motor and is connected right to the end of the crank and MAKES electricity when it is turned by the crank. It can also USE electricity to turn the crank since it also a motor. The sensation that the PCX engine starts immediately is because there is no gear and no gear noise or bendix that has to fly out to engage a ring gear like a regular starter motor needs. The Honda 500 engines use this as well. The CBR500R twin is so well balanced and counter balanced and the sensation of the ACG alt/ starter is so smooth and instantaneous that when you key that bike to life, it doesn't even feel like it is running.