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Post by teskow on Aug 15, 2013 18:10:59 GMT -5
How much better gas mileage will I gain if I go from a carburetor 250cc to a 250cc fuel injected machine?
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Post by rockynv on Aug 16, 2013 14:54:44 GMT -5
That depends on your riding style and the two bikes you would be comparing. Myself I ride to commute to works so no lolly gagging as I am on a schedule. With my 150cc carbeurated Lance Vintage I would get 45 to 50 mpg on 40 to 45 moh roads while my fuel injected Sport Cuty 250 gets between 70 and 80 mpg on the same commute.
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Best out of 8 scooters I've owned.
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Post by gregw on Aug 20, 2013 17:09:32 GMT -5
Not much gain. A properly jetted carburetor would get about the same gas mileage as fuel injected. The biggest advantage would be cold starts. No need for a choke on the fuel injected.
And, on a side note, I've had two fuel injected 250 scooters (Yamaha and Kymco), and neither one ever saw 70 mpg. Perhaps if I only drove 40mph from gas station to gas station without stopping... I consistantly get 55-65mpg.
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Post by prodigit on Aug 20, 2013 19:12:08 GMT -5
If you had a choke, you could tune the carb on the fly for the perfect fuel mixture! If your carb is tuned a bit too lean, you could use the choke to cut airflow a bit (richen the mixture) and find the perfect AF mixture (the bike will perform better on the perfect mixture). The benefit is that your bike will be performing optimally, with best performance and highest MPG. The cons are if your bike is too lean, you need to cut back too much on airflow with the choke, and if you're having a 250cc engine for instance, and cut back too much on running lean and on the choke, you could be getting only eg: 225cc's of fuel mixture in the cylinder, instead of the full capacity; so you'll get performance loss. But a correct AF ratio on a bike that's running only slightly lean usually outperforms an incorrect jetted bike (too lean) without choke modification (meaning without cutting back on the air). It also depends on the final drive gear, and CVT or manual, as well as average driving style (city with start-stop traffic, or country, with long roads at 35-40MPH, or highway with 60+ MPH roads. MPG is optimized when the engine RPM is as low as possible, while the speed is as high as possible. Most of the time, a ~200cc engine running at 1,5k RPM, going 35MPH is having the best MPG you can get out of a bike (even better than a 50cc at 6k RPM). I think the best overall bikes are the 200cc bikes. Power enough for the interstate (70MPH), and also power enough to pull the ride at 40MPH at the bottom of the RPM range (1500-2000 RPM). So the answer to your question is not an easy one. But just to give you some kind of an answer: The BMS TBX 260 with Fuel INjection gets 80+MPG. The Suzuki TU250x with FI gets  +MPG Most chinese 250cc carbureted bikes get 65-75+MPG. |
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Post by alleyoop on Aug 21, 2013 15:25:55 GMT -5
Unfortunately the scooter carbs do not have a CHOKE, they have an ENRICHER they work the OPPOSITE. A CHOKE CUTS OFF AIR so more fuel gets sucked out and ENRICHER by DEFAULT FEEDS EXTRA fuel for cold starting then CUTS OFF THE FUEL.
Alleyoop
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Post by prodigit on Aug 21, 2013 15:45:54 GMT -5
my mikuni carburetor has a choke.
The enricher principle is about the same. Kinda like an automatic AF ratio modifier.
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Post by Jarlaxle on Aug 22, 2013 11:28:16 GMT -5
I'm managing mid to high 60's from my carb'd Q-link...best tank was 71.
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Post by excal on Oct 31, 2014 20:33:17 GMT -5
Hardly seems worth the change over to save $ on gas mileage unless your going to keep it for 100K + miles.
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Post by alleyoop on Oct 31, 2014 21:25:37 GMT -5
You also have to consider the cost of repairs if something goes wrong on a EFI system the ECU alone runs 400+ buckoos.
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+MPG
..BAD TO THE BONE..
