FINAL 164CC setup with testing results!

[QuantiQualification]

I always fill mine on the center stand. Drop it from the stand, splash it around, put it back up on the stand and you'll likely find more space to fill. I wouldn't personally consider a fill level to be consistent or accurate as a single data point because of that. Not saying that over an average of more fill-ups you wouldn't come to around the same number.

I think the key here is if you don't slosh it around, it is pretty dead consistent at the fuel filler edge on the center stand. Next time I will do a test to see how much more one could stuff in if I close it up and then off the center stand then slosh and center stand etc. Would be interesting! Any last bit of fuel in possible is going to help these little bikes a whole lot at 111 mpg.

 

[QuantiQualification]

I get this as well. There's a reason I generally don't do the slosh unless I'm about to immediately get on the bike and ride another 10'ish miles, but I don't remember what the reason was. Something like it affecting a filter of some sort. Whatever the reason, I only slosh for fill ups mid or start of ride, and I average my fuel consumption over 5 readouts. It probably doesn't hurt the bike to do it, but it doesn't hurt not to do it too.

I think that would be important to not slosh/fill to the brim if you have an evap canister for emissions like on cars. I am pretty sure the little CT doesn't have one. I could also be reading what you said wrong. Sloshing when low might get air into the fuel pump. Shouldn't be a big deal though since the pump should be self priming.

 

[SneakyDingo]

Yeah, I'm not really sure why I don't do it, just that at some point someone said, "You could damage X" and I was all, "ok, it's never really been that big of a problem to not slosh, seems fine to me." When I was on the CDT though, there were a few times when I could see the bottom of the tank filling up, and that slosh did come in just a tiny bit handy.

 

[dmonkey]

A good reason not to fill it to the brim and then park it is that fuel expands with heat. Used to be a common thing to see fuel coming right back out the filler neck from under the gas cap of pre-1970s cars parked on a hot enough day.
USA model CT125s do have an EVAP canister, that's how it meets California emissions as a 50-state legal bike. It feeds back into the intake.

I think the key here is if you don't slosh it around, it is pretty dead consistent at the fuel filler edge on the center stand. Next time I will do a test to see how much more one could stuff in if I close it up and then off the center stand then slosh and center stand etc. Would be interesting! Any last bit of fuel in possible is going to help these little bikes a whole lot at 111 mpg.

Just curious, how do you know it's consistent? I would hardly trust even the same fuel pump to be consistent in measuring volume dispensed and left in the hose to the degree that makes a measurable difference in MPG for this bike. That's where multiple data points being averaged helps to smooth out inconsistencies.

 

[SneakyDingo]

A good reason not to fill it to the brim and then park it is that fuel expands with heat. Used to be a common thing to see fuel coming right back out the filler neck from under the gas cap of pre-1970s cars parked on a hot enough day.

Thanks. I'm pretty sure the expansion is the reason why. I've spilled gas on my crotch before when I didn't close the cap properly on my Ninja 250. As a result of that experience I'm wary of anything that involves gasoline being close to my balls now as a result.

 

[QuantiQualification]

A good reason not to fill it to the brim and then park it is that fuel expands with heat. Used to be a common thing to see fuel coming right back out the filler neck from under the gas cap of pre-1970s cars parked on a hot enough day.
USA model CT125s do have an EVAP canister, that's how it meets California emissions as a 50-state legal bike. It feeds back into the intake.


Just curious, how do you know it's consistent? I would hardly trust even the same fuel pump to be consistent in measuring volume dispensed and left in the hose to the degree that makes a measurable difference in MPG for this bike. That's where multiple data points being averaged helps to smooth out inconsistencies.

Yes, multiple tanks would be the best way. Not practical at 45 mph and at the WOT I have enough other tanks to make me feel comfortable with the calcs. Temperature is the biggest variable but I doubt the storage tanks ( of the fuel station) will change much if any. Agree on topping up fuel tank only when immediately planning on driving thereafter. As far as fuel pump accuracy, I will leave that to the NIST and weights and measures.
"In the US, the National Institute of Standards and Technology (NIST) specifies the accuracy of the measurements in Handbook 44,[12] though states set their own legal standards. The standard accuracy is 0.3%, meaning that a 10-US-gallon (37.9 L) purchase may actually deliver between 9.97 and 10.03 US gal (37.7 and 38.0 L)." Per Wikipedia.

 

[oldskool]

45 mph and 60+mph is a huge difference from an energy required/fuel stand point. Air energy goes up by the square of velocity. At 60 mph it is roughly 178% of 45 mph. Other resistances such as rolling might go down comparatively at 60.

Of course we all know this. Every vehicle will get less mpg after you pass the sweet zone. My 125 has gotten 111.4 average over 1000 miles of use. Mostly putzing around @ 45 MPH. I do not understand how one can add over 33 percent displacement and the other mods you have done and still get 111mpg @45 mph. Your goal was to increase power and performance. You have done so being able to exceed 60+ mph at WOT. I think your one small fill up is a bit "optimistic". As has pointed out its pretty easy to have errors with such a small sample.
I am glad you are enjoying success on your quest to make the 125 more suitable for your use. It is interesting but I have never seen mods that dramatically increase performance without some increase in fuel consumption, no free lunches. It would be interesting to see mpg average from a larger sample.

 

[dmonkey]

Flowmeters in the pump are precise at measuring the volume they move, but that doesn't account for the hose after it so the reading isn't necessarily accurate to dispensing. Consider that you could fill up from a pump two different times and one time the person pumping gas before you stopped filling when the nozzle clicked off for them at a full tank, leaving what's left and already been metered in the hose, free gas for you, the second time you fill up someone before you squeezed the trigger after the pump stopped and got every last bit from the hose. Could be a measurable difference for the types of pumps where that is possible. I've been stuck in the boonies low on gas with a closed gas station and topped off on what was left in the hoses there to make it to a town that actually had services open.

I don't mean to sound like a wet blanket here, I very much enjoy the great information, ideas, experiments, and experiences you continue to share. Just sharing my observations, I understand why someone wouldn't run the bike at WOT for multiple tanks of gas just to get a fuel economy reading, unless they were already going to be riding it like that. That's just the methodology that would make it a more accurate reading if that's what you were looking to obtain rather than a rough number. With the scale of these numbers a variance as small as 0.1 gallon could make for a 7 mpg difference in the result. There are a lot of motorcycle and car reviews out there that report a "real world" MPG off a first tank of gas, and they're often wildly inaccurate because of the potential issues with calculating from a single data point.

 

[oldskool]

Flowmeters in the pump are precise at measuring the volume they move, but that doesn't account for the hose after it so the reading isn't necessarily accurate to dispensing. Consider that you could fill up from a pump two different times and one time the person pumping gas before you stopped filling when the nozzle clicked off for them at a full tank, leaving what's left and already been metered in the hose, free gas for you, the second time you fill up someone before you squeezed the trigger after the pump stopped and got every last bit from the hose. Could be a measurable difference for the types of pumps where that is possible. I've been stuck in the boonies low on gas with a closed gas station and topped off on what was left in the hoses there to make it to a town that actually had services open.

Just sharing my experiences and observations here, I understand why someone wouldn't run the bike at WOT for multiple tanks of gas just to get a fuel economy reading, unless they were already going to be riding it like that. That's just the methodology that would make it a more accurate reading if that's what you were looking to obtain rather than a rough number. With the scale of these numbers a variance as small as 0.1 gallon could make for a 7 mpg difference in the result. There are a lot of motorcycle and car reviews out there that report a "real world" MPG off a first tank of gas, and they're often wildly inaccurate because of the potential issues with calculating from a single data point.

You reminded me of working at the gas station when I only had a nickel and a dime to rub together. When I closed down for the night I would MT the hoses, 8 pumps, into my KZ400s gas tank.

 

[dmonkey]

LOL, I appreciate you sharing. I feel less guilty about having done that now, it felt more unethical than just checking the coin return on payphones or anything like that. Not a lot of options when the only gas station in town closes and turns their pumps off at night. Not something I had adequately planned for.

 

[m in sc]

when i check mine, i usually ride the same 24 mile loop to and from work on it, and fill up at the same station.

also, we need to keep in mind different blends of fuels, summer/vs winter, pump accuracy as mentioned, etc. etc.

I agree that of course, measuring MPG should overall be done over multiple tanks and averaged to be a very useable data point, but this was just a snapshot.

On my rides, im rarely under 50 mph and my mileage for this reason, sucks. tiddling around i can get well over 85, but that's not how i typically, ride... , but i have. when in a slow group.

 

[QuantiQualification]

@oldskool @dmonkey I think we can all agree that the bike traveled 165.3 miles on a single tank of fuel, the opmid odometer/speedometer being well calibrated to gps. Beyond that, there is the potential for any number of errors with my methods as you have pointed out. So let's put a range on potential fuel economies of + or - 10% (which I think is quite reasonable) and we have a high probability that it is correct. So at WOT: 64-78 mpg and at 45 mph: 100-122 mpg. If you calculate based on Honda's claimed fuel tank capacity of 1.4 gallons then 118 mpg. The fuel economy at 45 mph will be worse than a stock bike since a stock bike should be targeting Stoic or leaner while my bike is probably at 13.5:1 on ethanol free. At 45 mph, stock and my bike will be using the same horsepower and therefore using the same amount of fuel if we were both running the same AFR all things being equal (which they are not). At speed, bigger engines are not necessarily more inefficient than smaller engines if geared to compensate. If anything, a higher compression larger capacity engine will be more efficient than a lower compression smaller capacity engine for a given unit of fuel.

 

[JPMcGraw]

Since we are o the subject of fill ups. When i fill up the CT the pump doesn't auto shut off when the tank is full. My ZX6R was so long ago i don't remember. When i filled up my SO's Metro the pump shut off by itself when it was full.

Does the pump auto shut off for anyone else or was that just a weird fluke with the Metro?

 

[dmonkey]

The automatic shut off mechanisms use the venturi effect to shut off when the little secondary hole in the tip of the nozzle is covered in fuel, which is different from when the tank is full. If you click the trigger to a fast flow rate position it can fill fast enough that the shut off isn't very effective, it will click off around the same time as spraying everywhere since there isn't a long filler neck on the CT nor can you seal the nozzle into it. I don't rely on the automatic shut off when filling motorcycles. For motorcycles where the nozzle can be more fully inserted than on the CT fuel tank it will stop filling way too soon as the nozzle tip ends up being part way down in the tank. The CT has such a small tank I just hold the nozzle slightly above the nozzle blocker bar in the filler neck, squeeze the dispense trigger manually for slow flow filling, stop when I can see the fuel level rise high enough, and then give it a few trigger presses to top it off. If the next gas stop is very far away then as mentioned I'll drop it from the center stand, splash it around a bit, and top it off even further.

I'll admit that for motorcycles I have no idea how you are supposed to use the pumps that have a vapor recovery system that requires the nozzle seal to the filler neck. They work just fine when filling up a car or truck and surely help with vapor emissions, but they clearly weren't designed with a requirement of working with motorcycle fuel tanks or gas cans, nor did that prevent them being required by legislature in some areas. Last year I bought a gas pump card to defeat that control and turn filling into a one handed operation where you don't have to hold back the nozzle foreskin with your other hand.

 

[ssaigol]

I think this bike is limited by its emission control. The combination of catalytic converter and FI programming limits its power output. Honda 125s the world over, even the pushrod OHVs can go over 60mph.

 

[oldskool]

I think this bike is limited by its emission control. The combination of catalytic converter and FI programming limits its power output. Honda 125s the world over, even the pushrod OHVs can go over 60mph.

Make sense The EPA has really hobbled ice vehicles in the USA. Like most things of this nature it starts out good but being a government agency common sense gets left in the dirt. They insist on the last small fractions of gain at the expense of practical application.

 

[QuantiQualification]

I think this bike is limited by its emission control. The combination of catalytic converter and FI programming limits its power output. Honda 125s the world over, even the pushrod OHVs can go over 60mph.

@m in sc suspects timing not being able to advance.

 

[dmonkey]

The USA was not the CT125's first market, Honda makes decisions based on changing international requirements. The latest model 125cc mini motos were built to meet Euro-5 requirements, which doesn't require much additional equipment or modification to conform to AC (49-state + California) requirements. The specs of the Trail 125 vs Super Cub show that for nearly the same engine the Trail is tuned for torque while the Super Cub is tuned for horsepower, which makes sense for the types of bikes they are sold as.

 

[m in sc]

all of my emission controls were removed, its the timing curve, im 100% sure of it. thats why standalone ecms can go faster, different timing tables.

 

[QuantiQualification]

Here's the big slosh!

STUFF MORE FUEL??? Honda Trail 125 gets some!

Please subscribe @ https://www.youtube.com/@QuantiQualification?sub_confirmation=1I squeeze the last drop of fuel into a CT125!

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