101.5 MPG on my 2003 Ninja 250!!!

[gtkid2002]

I think the carb / EFI bit is all down to preference. I don't get Carbs very well, and I understand FI decently enough.

Probably the ONLY reason I would think an EFI kit would be super-awesome for a regular hypermiller, would be the ability to hook up something along the lines of the mpguino.

But before this goes completely into a carb VS. EFI argument,

theycallmebryan - Which website have you been communicating with?

Also for those of us not familiar with carbs/ninja's, how difficult might it be to lean the bike out a bit?

[dcb]

fyi, I may take a stab at a fuel injection conversion on the gs250, I have a spare set of carbs and some injectors/sensors off a cbr600rr. I would stick with the carbs but they do not like my current set up, bike runs crappy regardless of what carbs I use after intake tract mods, and I was never very good at guessing jet sizes and annoyed with removing/reinstalling carbs during that bit of trial and error.

All my bikes to date have been carbureted, and it is generally a very reliable setup, I don't ever recall being stranded because of a carburetor (well maybe twice). But I do want to see if I can do better with fuel injection, as well as having super easy tuning (just tweak the fuel delivery map) and am definitely looking forward to realtime consumption feedback to help in that regard as well.

[user removed]

Started working on cars in 1965, had to if I wanted something to drive. First injected car was a 73 Alfa Romeo GTV in 1977. Marelli system with a mechanical FI pump and injectors like a diesel but not as high pressure. Pull throttle on the dash and thermal sensor for enrichment at the pump.

These days it's all FI and the vast majority of them are electronic. OBD systems make diagnostics much less of a mystery but you can still slip betewen the cracks with some problems, particularly intermittent. The worst I ever saw for intermittent was every 6 months per malfunction. You never saw this with carbs and 0 feedback systems. The early 1975-77 Nissan Z car systems were very reliable and many are still working on the original ECU, but it was just a basic system compared to today.

Either carbs or EFI has their plusses and minuses, and in many cases it's the age and background of the individual that determines their preference.

I'll take the very complex system on the Altima, and the very basic system on the Honda Rebel, with the Rebel's electronic ignition system over the points on the 71 CB350. The Rebel is even functional with total battery failure which is something I really like.

Maybe I just don't trust the elctron pathways as much as many of the younger folks here. One the other hand I see people every day moving though traffic and I can tell that they probably never drove a carbureted car in their lives. Mechanical systems tended to fail in a predictable manner and a weak accelerator pump made you a more cautious driver in the old days.

I prefer mechanical but there are certain areas where electronic is essential, but I don't absolutely trust either like many do these days.

Diagnostic nightmares certainly have proliferated with modern systems and I have seen cars junked for relaitvely simple problems that were considered unrepairable by many experienced techs, to the point where the owners gave up on the vehicle. While you can argue the tech was simply not good enough, you will never argue the system complexity has not progressed exponentially. If you want to use that rationale just compare the wiring diagram on a 37 Ford to the one on my current Altima.

regards
Mech

[gtkid2002]

Oh, kind of off topic post here, but..

theycallmebryan - How well does your Ninja do over hills? Would you recommend that setup in an area with some grades on the freeway, or not so much?

I ask because I live on a 600' hill basically, and pushing a 300 pound bike up from sea level does not sound like a very good use of my time. And western Washington isn't known for being.. well.. flat, especially through Seattle and further north.

Or if someone could point me in the general direction for results from re-gearing a Ninja or motorcycle. I'd guess the rules would apply for all bikes, just minor differences from power bands and such.

[theycallmeebryan]

Originally Posted by gtkid2002

Oh, kind of off topic post here, but..

theycallmebryan - How well does your Ninja do over hills? Would you recommend that setup in an area with some grades on the freeway, or not so much?

I ask because I live on a 600' hill basically, and pushing a 300 pound bike up from sea level does not sound like a very good use of my time. And western Washington isn't known for being.. well.. flat, especially through Seattle and further north.

Or if someone could point me in the general direction for results from re-gearing a Ninja or motorcycle. I'd guess the rules would apply for all bikes, just minor differences from power bands and such.

You can still climb hills just fine, just not in 6th gear. Think of a 15/39 setup as 1st gear being the stock 2nd gear, 2nd gear being the stock 3rd gear, and so on. If its a steep upgrade, just downshift and you will be fine. Besides, on long upgrades, its better to move your engine into the peak torque range (on a ninja thats between 6,000-8,000 rpms).

New Jersey and New York have their fair share of elevation changes, especially where i ride. On easy upgrades i don't have to downshift, I'll just lose 5-10mph with a constant throttle position.... but i'll make up that loss on the downhill that follows.

[theycallmeebryan]

Originally Posted by gtkid2002

I think the carb / EFI bit is all down to preference. I don't get Carbs very well, and I understand FI decently enough.

Probably the ONLY reason I would think an EFI kit would be super-awesome for a regular hypermiller, would be the ability to hook up something along the lines of the mpguino.

But before this goes completely into a carb VS. EFI argument,

theycallmebryan - Which website have you been communicating with?

Also for those of us not familiar with carbs/ninja's, how difficult might it be to lean the bike out a bit?

I have been talking with these guys:

Small Engine EFI Kit - Small Engine EFI | Engine control

[gtkid2002]

theycallmebryan - Just curious, did you ever finish playing around with the design you were working on in Solidworks? Seems like something that would be pretty cool to see.

Hopefully the EFI thing will be a decent investment. A friend is now looking at a newer Ninja, so I might be able to see what kind of MPG's his gets with rather "spirited" riding constantly.

[mrstarr]

I have a 1987 Honda Rebel, that gets about the same gas mileage, and I know my gas mileage varies WIDELY depending on (1) the air temperature (2) the speed I drive (assuming constant) and (3) the weight on the bike. Depending on the time of year and how fast I drive, it can be as low as 50, or as high as 90+, on a bike I've loaded up with accessories.

I may be incorrect, but the hotter gasoline is, the more efficiently and thus explosively it combusts. You're going to get your best gas mileage in the hottest time of summer, and worst in the cold of winter. On the other hand, colder air is denser, containing more oxygen, however, it also means the air is more dense outside the engine too, leading to higher air resistance.

In your measurements, air temperature was not kept a constant.

Further, the slower you drive, the higher your MPG will be. At 85, your MPG will be horrid. Drive at moped speeds of 35, however, and you will see some awesome numbers. Indeed, mopeds regularly get over 100mpg without trying, simply because they only go 30mph and are extremely light.


Adding heavier tires does not seem like it would raise the MPG... the converse is true. You should be trying to shed as much needless weight as possible. The less you have to move, the higher your mpg.

Gearing up the sprocket, which I have done on my bike as well, may add a few mpg depending if the speed you are driving is at a gear just where the bike is lugging along in the highest possible gear, where you are making every explosive vapor of gas work the hardest to push the bike along and maintain its speed.

In other words, as an example, you're in 5th gear, driving at 35 mph, and the weight and pressure of moving the bike is pushing hard against every little combustion explosion, like a mule grunting and straining hard to pull a heavy load forward.


At any rate, you need to redo your tests where (1) temperature is a constant, and you list that constant (2) speed is a constant, and you list that constant, and of course (3) weight is a constant. And then make your charts, where you vary all of those but only one at a time, and chart how much each impacts your miles per gallon. I would start by keeping temperature and weight constant, and charting at the different speed ranges. Then next test, I would for each speed range, chart where the speed stays constant, but the temperature changes.

Weight... pretty obvious what that will do... less is more... but on say 500 pound bike, how much will taking 10% off add... 20%... and so on...

[alvaro84]

Herr Starr, I'd have already made this sheet if Teresa had any instant FE display, because I'm very interested. Filling up is quite inaccurate though, I just can't fill to the exact same point. I even use the distance between low fuel light instead of the fillups because of this, but I suspect that the fuel level sensor isn't accurate either This inaccuracy can be attenuated by long distance tests, but who wants to do the same test over and over, for several thousand kms? And wouldn't that be a total waste?

So I won't ever had 'clean' data without the strong noise of everyday use. Temperature, wind(!!!), rain, traffic conditions are going to distort my data, no matter what.

In my case speed dependence is an even trickier factor, because I can't shift into 5th before reaching ~70km/h (43.5mph), and even 4th begins at ~50km/f (31mph) so it probably isn't a smooth curve at all.

All I can say about it that 4th is probably somewhat more efficient than 5th if I go at its bottom, I've tested it this winter when I was cold at higher speeds I don't have any usable numbers on it, though. My worst solo tank was 3.23l/100km (72.8mpg) this winter, but I can't really compare. I rode in colder weather than a year before, and I rode much more (the winter before the tank I filled at the end of December lasted till 20th of March, this year I had 5 fillups in that time interval. Probably because of the less snow.)

Weight? I ride both 1-up and 2-up, and I can say that an additional ~160lbs passenger makes FE worse by no more than ~10%. I can't be sure again, because of the lack of a scientific test.

[sc2dave]

what about something like this for the carbs? Scaryfast Racing Home .you can make your own, http://www.thumperfaq.com/downloads/JamesNOW!.pdf