New fuel injection retrofit kit for the Ninja

[ProDarwin]

I wonder if anyone will see any significant power gains with the kit. If so, I'd consider getting a newer Ninja and putting the older (more powerful) engine in it. I always thought that bike was like 10hp shy of being fantastic.

[drmiller100]

narrow band is just fine if you are looking for mileage.

narrow band, and a feedback loop of some kind allows the engine to find its happy spot.

At WOT, or even heavy loads, you can tune by just adding fuel from stoich until it runs with the most power. again, not really hard to do.

I would not buy fuel injection in hopes of more power - my experience is carbs usually make as much power as most bolt on fuel injection systems.

[jkv357]

Originally Posted by ProDarwin

I wonder if anyone will see any significant power gains with the kit. If so, I'd consider getting a newer Ninja and putting the older (more powerful) engine in it. I always thought that bike was like 10hp shy of being fantastic.

I don't think you'd see any gains that large. The Euro-spec EX250 is FI, not sure if it makes any more power than the carb version but it would be interesting to see.

As far as the newer engines being down on power, it would be a lot easier to do a cam swap + pipe to get whatever is available. Pretty sure it's the cam that changed the output, as I believe they were trying to bump the midrange up from the previous version. Carb size stayed the same pretty sure.

One advantage I can see from these FI conversions (for the person interested in mileage) would be dropping down in venturi size. You'd be giving-up some power of course, but I would think you could pick up some MPGs if you were tuned for your cruising RPMs and not top-end power. The Ninja engine makes peak torque and HP way up there, and everything (cams, carbs, etc) supports that end of the spectrum. Anything you could do to drop the torque peak down closer to cruising RPM would help. Seeing as how biased the engine is toward power at high RPMs I'm really amazed they get the mileage they do when cruising, especially if they are geared up.


Jay

[sendler]

Originally Posted by ProDarwin

I wonder if anyone will see any significant power gains with the kit. If so, I'd consider getting a newer Ninja and putting the older (more powerful) engine in it. I always thought that bike was like 10hp shy of being fantastic.

Off the shelf pipe/ jet kits can get the Ninja 250 to 30hp. 26hp of the stock engine can already take it to 7 seconds 0-60mph and 14s for the quarter mile. Plenty fast unless you just want to do wheelies. The peak power of the new gen and old gen are almost the same. The new gen cams are supposed to offer a better midrange but the power is still very much toward the top compared to my CBR250R. The nice thing about FI would be to get consistent performance regardless of weather and altitude when traveling and improve the fuel economy while doing it. A jet kit on that bike takes the FE right to the low 40s mpg range.

[ProDarwin]

Interesting. I had an older one... it was fun, but a few more HP and it would've been great. I averaged high 60s with it, and had fun doing so. Having the power up top doesn't bother me in the least... right now my fun car is an S2000.

I recall reading tests that the newer ones only did 15s in the 1/4 and dyno up to 5hp less. I much prefer the newer look, chassis, and geometry.

[sendler]

Originally Posted by ProDarwin

Interesting. I had an older one... it was fun, but a few more HP and it would've been great. I averaged high 60s with it, and had fun doing so. Having the power up top doesn't bother me in the least... right now my fun car is an S2000.

I recall reading tests that the newer ones only did 15s in the 1/4 and dyno up to 5hp less. I much prefer the newer look, chassis, and geometry.

Maybe .5 hp less

[jkv357]

For anyone following that's curious, here's what I came up with for comparisons of new ('08 and above) and old ('07 and below) Ninja 250 engines ( Iron Ninjas!! Battle of the 250s! - Page 3 - ninjette.org) -



and comparisons between Euro FI and U.S. carbed engines, via the Service Manuals (Iron Ninjas!! Battle of the 250s! - Page 2 - ninjette.org) -

Euro:

Alésage x course 62,0 x 41,2 mm
Taux de compression 11,6:1
Distribution DOHC, 8 soupapes
Puissance maxi 33 ch (24 kW) à 11 000 tr/min
Couple maxi 2,24 kgf m (22 Nm) à 8 200 tr/min
Type d'alimentation Injection : 2 x ø 28 mm (Keihin) Double papillo


U.S

Bore And Stroke: 62.0× 41.2 mm (2.5 × 1.6 in.)
Displacement: 249 cm³ (15.2 cu in.)
Compression Ratio: 11.6
Maximum Horsepower: 23.4 kW (31.8 PS) @11 000 r/min (rpm),
Maximum Torque: 22.0 N·m (2.24 kg·m, 16.2 ft·lb) @9 500
Carburetion System: Carburetor, Keihin CVK 30× 2

So based on that info the older engine makes 1.36 more HP than the newer one and the Euro version with F. I. makes .6 more kW (.82 HP) of power than the carbed version. That's assuming many other factors are identical.


Jay

[ProDarwin]

Huh, guess the peak isn't that different, however the area under the curve up top appears to be significantly different - older engine makes around 5hp more @ 13,000 rpm. Thanks for the info.

[bondvagabond]

These have been out for a while now, anyone else playing with them? I am thinking of throwing one on a 1979 honda xl250s. factory they get 70-80mpg, what kind of increase do you guys think i would get by going efi?
I would have to sort out the increased load on the electrical system. Don't know if they would work with my bikes 6v system.

[renault_megane_dci]

The sucessfull build thread link on the web site leads to a fellow who got his 50 scooter up from 80 mpg to 109 mpg.

In my opinion there are room for improvement in his build (O² sensor probably hurts exhaust flow & 24 mm TB is probably on the large side for a 50 4 stroke (although I red it is not much an issue when switching to injection)).

That being said, the % of improvement and fuel price in France tells me it would take 34000 kilometers (22K miles or so) to pay for itself on my 250.

Very tempted but the exhaust layout on my bike is really not helpfull in installing this setup (twin header on a single with no balance pipe)