Yeah, weight is not an issue...
Weighs about the same, and the ECU's are about the size and weight of a CDI if that.

No, it's not going to make a major power increase over a perfectly jetted carb... I mean I am sure there is a little more from better atomization when injecting the fuel, and some from variable ignition curves. But not a major difference.

Where you can't match it is in throttle response, and in changing temperature and altitude. Those are all really nice reasons to me.... Because I tend to focus more on my machines being quick and responsive in short bursts rather than only wanting top speed. I also tend to ride from one lower elevation, into places that are not only higher elevation, but also high enough to be much cooler. And too, the general temps here in the hot months tend to jump back and forth over that range where you need to move back and forth a jet size in order to have optimum performance... which I do not do.

So it's nice that even my 450's simple open-loop system can adjust itself for temperature and altitude.... so I am never giving anything up.

Maintenance-wise, the fuel injection is less to worry with in terms of moving parts and likely complications, etc. No bowl, no float level, no jets, no mixture screws, and nothing seal-wise but some o-rings, and less moving parts....

So it's lower maintenance and less aggravation in that aspect, when nothing is wrong.

The trade-off is the additional electrical in an off-road application, and the sensors and such. A lot of complication, and room for failure if dirt, mud, water, etc were to work it's way in... and there is always the possibility of rubbing a wire naked, or popping a fuse, etc...

And, should something go wrong, it's harder to figure out what is wrong, harder to fix yourself, and more costly to repair.

With all the nagging carb issues I've had this year though, I'm OK with that.

 

Kevin,
My opinion does gravitate towards the EFI because i noticed some of your uses involved pretty frigid temps. EFI=easier cold weather starting. Head to the store and grab this month's issue of atv action. There is a 10 page section in it in which they took the exact two quads you are considering along with two others of the same c.c. and ran them through various tests and evaluated and compared them top to tire. This may be of use to you. It was helpful to me as i was torn between the same two you are now. Don't want to influence your decision so i won't tell you which one i bought but i love it. From the looks of this page though, i think you're getting plenty of knowledgeable advice.

 

Carb = easy cold starts
EfI = easier cold starts.

There are 2010 snowmobiles with carbs still and I have as much Northern Ont Canada winter miles on my ATVs as summer. What you call a cold day we call a warm day I guarantee it.

 

just looking at those pics made me cold........but yeah, buy EFI.

 

No kidding!

 

Thanks guys. Been aways for awhile.
I am a proud new owner of a Suzuki KQ 450. Although I like the 450 Grizzly, I would hate to deal with the re-jetting stuff when I take it elk hunting in the rockies. The KQ 450 feels nice and well balance and have enough "uummph" for me to do what I needed to do.

Kevin.

 

Congrats on the new Zuk! I'm sure she will treat you well. I would like to add for any one else looking to choose, I wouldn't let carb vs efi be a huge deciding factor unless you are looking at frequent large elevation changes. It isn't unheard of for the top xc racing guys to convert an efi machine back to carb. Why? Because a properly tuned carb can actually give you an advantage over efi in dead engine starts. I have witnessed this myself, especially the KFX450Rs tend to be slower starters. I know it is a little harder to change jets on a ute with having to remove extra bodywork and all, but usually you can just go up a size or 2 on the pilot, one size on the main and you are good to go. An easier alternative is to use the UNI air box lid vents, and use some duct tape to cover the vents as you go up in alt or temps decrease. Living in Western NY, we get a pretty decent temp swing between seasons, I have owned plenty of carbed machines over the years, they all started as well in -5 as they do at 90 when properly jetted.

 

It's true... I own a KFX450R... and it can start slower at times.
It always starts well, just sometimes it does not fire as fast as a carb would.

I think most of it is due to a tiny battery, only 85 cold cranking amps, yet more power draw at startup due to all the extra electrical, fuel pump, etc...

 

I vote EFI. You listed a lot of cold weather uses in your message starting this thread. I hate playing with a choke and spending 5 minutes warming up a carburated engine when EFI machines start on the first crank and then I just go.

 

The carbs days are numbered!!! The CRF250F MX bike gets fuel injection this year (the only FI 250 out there), and the CRF450F already had it. This will filter down to the CRF450/250X cross-country bikes soon, and the TRX450R as well! And, a 3/4 frame size TRX250R would be sweet....

Sure, the slow economy will probably delay things, but it will all happen sooner rather than later!