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Carb vs. EFI
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February 9, 2010 at 8:09 pm #3698ziberzabaParticipant
So I’m looking at buying my first bike this spring. The bike I’m looking at is available with a standard carburetor, or I can get the exact same thing, but with EFI instead. This honestly the only difference between the the models, except that the EFI outputs about 1.5 more hp than the one with the carb. What I’m wondering is: should spend the extra $850 to get the EFI? Would it be worth it?
February 9, 2010 at 8:13 pm #24480briderdtParticipantWhen I was looking for a bike, I had this irrational fear of carbs. Why? Well, I love wrenching on bikes. BICYCLES that is. Add an engine and I get the heebie-jeebies. So I went with the SV650s (the Ninja 650 was right in there too) because all the smaller bikes were carb’d.
I’ve survived to tell the tale, but if I were to do it all over again, I’d probably go with a Ninja 500 (or even 250) or the GS500 and not give a rip about the carbs.
February 9, 2010 at 11:10 pm #24482eternal05ParticipantIf this is a beginner bike, chances are that $850 is a ton of extra money. In that case, I say no. Don’t bother.
EFI is definitely better than having carbs in just about every way, but it’s a matter of convenience, not a matter of life or death, and in my opinion it’s certainly not worth $850 on a $3000 motorcycle.
February 10, 2010 at 12:53 am #24488TrialsRiderParticipantIn my experience simple carburetors are easy enough to work on which is a good thing, because they tend to be the highest maintenance dependent parts on a bike. Particularly since the advent of non-leaded fuel, todays high price, lower octane gasoline has an extremely short shelf life and left to sit for extended periods, will completely gum up the carburetors float bowls and tiny passageways.
The most complex carburetor design is the CV (Constant Velocity) type, occasionally referred to as an OE type carb. Motivation for manufactures to install CV carbs on modern bikes is an economical way to increase fuel efficiency, control pollution, and ‘smooth’ throttle response. The down side is; CV carbs are considerably more complex and difficult to tune, they have many more parts, including rubber vacuum hoses, o-rings and bladders that must not leak any vacuum, sometimes accelerator pumps, and possibly even electric sensors.EFI while not particularly simple or economical, is far the best performer of the bunch. It mostly works perfect or not and servicing equals replace parts. There are relatively few parts and nearly anybody can replace parts, right? …so EFI is my favorite. On the plus side; in addition to sometimes incredible performance gains, EFI provides better fuel economy, non affected by altitude change and better pollution control. It also heats the fuel in your tank, which is nice for keeping your legs warm in cold weather. On the down side; on a hot day stuck in traffic, it can actually heat the fuel to a boiling point ! …once experienced that very scary thing myself Because the fuel constantly circulates through your motor under considerable pressure, fuel filters are larger metal canisters making them more expensive, and leaks in the pressurized filter, pump or fuel lines will result in crap performance, but not necessarily strand you Also you can’t bump start most EFI equipped motorcycles …if you hear the fuel pump hum before it starts, that bike requires a good battery, or jumper cables to run.
February 10, 2010 at 4:47 am #24495ziberzabaParticipantHoly, thanks for the awesome info! I’m not entirely sure what bump start is. It sounds like a drop start, so I’m gonna guess it’s the same thing (starting the engine with the transmission). The weird thing is that this bike has both a functional kick start and an electric one as well. So I don’t know if that would remedy that problem. How hot was the ambient temp to boil the gas? In Minnesota we rarely have days above 100. Maybe 2 tops a year if we’re lucky. Most of the summer is spent in the upper 80s with a couple weeks in the low-mid 90s. I’ll probably go with the EFI from what I’ve read. I’m not changing altitude often, but I’m not really into cleaning my carb every spring when I bring the bike out of storage. I just wish I could find a used one. No one seems to want to get rid of theirs. So I will have to buy it new, but it falls within my price range. They also have relatively cheap OEM replacement parts should I drop it, and there is no plastic to worry about. Thanks again for the info. You’ve made the decision that much easier.
February 10, 2010 at 6:50 am #24496eternal05ParticipantMan that was a great post. Thanks for taking the time to write that up, Mr. TrialsRider!
February 10, 2010 at 7:26 pm #24507CBBaronParticipantFrom a users perspective EFI is simpler. Turn the key and hit the start button. It either works or something needs to be fixed. No choke adjustment, no carb adjustments, no fiddling.
From a mechanical perspective it is more complex. There is a fuel pump in the tank, an electronic engine controller and multiple sensors. Carb problems can usually be fixed on the side of the road with basic tools. EFI problems usually require replacing parts. You should have to “fix” problems with you EFI much less often.
Personally I find working with carbs to be an art that I am not particularly attuned to. I’d rather get EFI if given the choice. However for my first bike I wanted cheap, easy to ride and in good shape so a carburetored Ninja 250 made much more sense than a 650 at over twice the price.Craig
February 10, 2010 at 9:55 pm #24512Gary856ParticipantBump start means pushing (or coasting downhill) to get the bike up to speed, pop the clutch to spin up and start the engine. Usually it’s done when the battery is too weak to crank the engine.
February 10, 2010 at 10:01 pm #24511Gary856ParticipantA couple of points TrialsRider wrote about EFI didn’t seem right so I checked with a bike mechanic:
EFI heats the fuel in your tank –
I understand the fuel pump located in the tank get hot during operation and uses gas in the tank as a coolant/lubricant. However, the bike mechanic I spoke to said that, as long as there’s a reasonable amount of gas in the tank (not down to the last few ozs), the fuel pump does not heat up the gas by an appreciable amount, and certainly not to be felt by the rider on a cold day nor boils the gas on a hot day! On a hot day, if you top off the tank fully in the shade then move and sit in the sun, the heat from the sun could expand the gas in the tank enough to cause overflow. Was that what happened?EFI bump start –
Cranking the engine is what demands the most battery charge/power. If the battery is too weak to crank the engine, but still has enough charge to run the fuel pump (the humming noise you can hear with the ignition on), then you can still bump start a fuel injected bike. If the battery is completely dead, then you cannot bump start either a carbureted bike or a fuel injected bike, because there’s no spark.February 11, 2010 at 12:21 am #24514TrialsRiderParticipantMost will never experience the extreme fuel heat that I did, but I could easy prove it seeing as I still regularly ride that same bike. The circumstance on that particular day was; mid day record breaking high temps, stuck in clutch slipping, creep ahead traffic, westbound QEW near downtown Toronto. The bike engine is fully faired, longitudinal inline 4 cylinder engine where the cylinders lay flat along the left side of the bike, the fuel rail runs the entire length of the engine cylinders and within 1/2″ of the heads and barrels. The tank was less than half full, partly because I had been stuck in traffic for so long and the bike was nearly new. Considering this bike is a 1986 model (BMWK100RS) it represents possibly the earliest example of production EFI equipped technology and in typical BMW overkill fashion the fuel pump is huge in comparison to the one on my 4RT trials bikes. As recent as last fall my tank became so hot on the legs that I did fill up with nice cold fuel, simply because, as your mechanic suggested the fuel temperature is much lower given the full 5 gallon capacity. I live in Canada eh;) so I know about cold riding and regularly warm my freezing cold hands on that toasty warm tank Everything except the rubber, oil, filters, battery, fork seals, break pads and muffler is original and it has never stranded me in that many years!
I buy lawn tractor batteries because our winters are devastating on OEM batteries at three times the price, they are exactly the same size, except the poles are on the opposite ends. If the battery is flat it will not bump start even going down a huge hill, and with the engine spinning at that speed the alternator will still not produce enough electricity to achieve fuel pressure, but I can jumper cable start it and ride home on that same dead battery.Now for the opposite end of the EFI spectrum; …sorry but this is gonna kill your no battery no spark theory! My 2008 fuel injected Montesa/Honda 4RT has no battery. How do they do that? …a super efficient alternator ( inside the left engine casing, bathed in oil ) and an extremely small efficient fuel pump, which incidentally takes up much of the space inside it’s 2 liter fuel tank, (that’s a mere 67 ounce fuel capacity), so needless to say it only has a few ounces of fuel to work with much of the time. ..in events I fuel that bike every 1 or 2 loops, also in part to keep the fuel temperature down.
BTW idle speed setting on the 4RT is critical, it will not start if you touch the throttle at all during start-up. It requires a nice slow continuous kick, starting at compression and if you jump on it hard and fast it simply won’t fire. If it isn’t operating perfect, you let it run at idle for about 5 minutes and the computer sorts itself outFebruary 11, 2010 at 12:59 am #24515IBA270ParticipantOld K-bike tanks get so hot on the lower left hand corner (right on your left inner thigh) that it WILL BURN you. It’s crazy how freakin’ hot they get, especially as the fuel level get’s lower. I put 167K on a K1100RS…best bike I ever owned, except for that little detail!
Some EFI bikes can be bumped, and some can’t. Beemers, for some reason, cannot. At least my K-bikes couldn’t. Haven’t tried with the oilheads. There are other issues for more advanced bikes with low batteries to consider as well, namely the ABS systems and faults that are difficult to clear when they are jump started.
Smartest thing to do, regardless of bike, is to invest in a battery tender. Hook it up are you ride each time, and your battery will last a very long time. I got four years out of a battery, which is generally unheard of.
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