The Honda PCX / Forza / ADV150 / SH Forums

Love my bike. I ride a lot in town and some on the highway.

Here's the thing. When I accelerate nice and easy for a full tank I get worse fuel economy. That's correct, worse. I have verified this on at least 5 tank fulls at different ambient temperatures and with and without a passenger. Now the fuel use is still unbelievably low but it consistently gets 2.3-2.4 liters to hundred km. Or 100 MPG US/120 MPG UK...42.5 liters per 100 km.

If I ride it with WOT starts up to speed and do everything else the same I get 2.1-2.2 liters per 100 km or 109 MPG US/131 MPG UK...46.5 km per liter.

Crazy

Any modifications to the engine or transmission?

I've started tracking my economy recently; 3 tanks ago I came in at 44.94 km/l - next tank had a bit of WOT so the economy dropped a little - but with the last tank I went all out ... gentle accelerations - even stopped & turned the engine off and coasted down a few km of hills over the tank just to try to squeak it past 45km/l. That tank came in at 44.46 km/l. So I know what you mean!

WOT kills my economy completely though - with city riding (typically about 55km/hr) I get to about 220 or 230km before the last segment starts flashing but if even 10km out of 30km per day is at WOT then I only get about 180km before the last segment starts flashing.

So for me anyway, the economy has proven to be pretty much proportional to the speed I'm doing - other factors like gentle acceleration & braking and/or pillion passenger don't seem to make a big difference.

Hope this helps.

The bike seems to be most economical in the 30-40mph range with slower starts than WOT but not too gentle (clutch grazing with stock clutch). Starting with WOT may or may not make too much difference for most people, keeping WOT going when the bike passes mid range mph probably will use lots more fuel.

So the lesson is that WOT running kills fuel economy, but jackrabbit starts don't?

Smaug wrote:So the lesson is that WOT running kills fuel economy, but jackrabbit starts don't?

That's what I've found.

In theory, a fast start will use more, but in practice I suspect that the AMOUNT more that it uses is statistically insignificant if the ratio of starts to number of km ridden is small.

you you: I found this bone stock AND after the NCY variator and 13G rollers. Both at continuous highway speeds around 85km/hr and around town.

All, I am thinking it's mainly because of light overall weight. So reaching cruising speeds faster (and then it can spend more time using lean fuel mapping) allows betier overall economy.

I get over 105 MPG (U.S.) consistently and 118 MPG sometimes on 87 Octane Shell Unleaded Regular with 10% Ethanol.

The riding is mostly 25 to 45 MPH locally. No interstates.

I just filled up my PCX this morning. Over the last tank, I've been riding only in the suburbs. Average starts; not trying to be quick, just quick enough to not be a nuisance. Gentle throttle. Top speed for that tank was probably 50 mph. (81 kph)

Result was 110.3 mpg, my best ever.

I had one tank at 94 mpg or something, but that can always be caused by filling up to a lower point. Since the tank is only 1.6 gal., that can have a huge impact on calculated fuel economy. We have to consider the average to be the accurate one.

Very True Jeremy. That's why I am so careful to use the same brand/octane and same level. That's also why I waited to post until I had several instances.

Smaug wrote: I had one tank at 94 mpg or something, but that can always be caused by filling up to a lower point.

I remember the first time I filled up - book said only fill to the bottom of the neck and I'd gone a bit higher and was a bit worried. Not sure when all that changed, but these days I put it on the centre stand and fill it to the point of overflowing (for max range and consistency) and have never had a problem.

I suspect best economy is around 60km/hr (in theory, the lowest speed / RPM that the variator is maxed out) - after that it's probably inversely proportional to speed. Wish I had the model with the instantaneous consumption readout.

If one were super-keen to find the sweet spot then one way would be to fill it right up and then go do "X" distance at a certain speed then refill. Rinse and repeat for different speeds (but same distance).