Jump to content

  • Do you own an ATV? Join our Forum!

    As a member, you can post in our forums, upload your photos and videos, use and contribute to our downloads, create your own member page, add your ATV events, and even start your own ATV club to host your own club forum and gallery.  Registration is fast and you can even login with social network accounts to sync your profiles and content.


Is a fuel injected YFZ worth the extra $

Recommended Posts

I'm looking to get a YFZ 450 and I'm wondering how much benefit I would get from buying an 09 or newer. I hear carbs can be a hassle but is it really that big a deal? Btw this will be my first quad since I was 12 years old. I have ridden street bikes quite a bit and I never had any problems with my carb. Educate me?

Share this post

Link to post
Share on other sites

i like the idea of it myself ... here is a good read from venom performance ...

Fuel Injection: Better than Carburation?

It's easy to think of Fuel Injection as "an electronic carburetor replacement". Because it truly is no more or less than that. It is a device that mixes fuel with the incoming air so that the mixture is ignitable in the combustion chamber. Fuel Injection can be a wonderful thing, but it isn't as simple, or reliable, as carbureting. Fact: there is a lot more things that can go wrong with FI than with a Carb. There is the same power potential with both, too. Neither one forces air into your engine. They are both just ways of mixing fuel with what airflow the engine is pulling in.

1. Decades before there was Electronic Fuel Injection, there was Mechanical Fuel Injection, even on some of the first Corvettes, although they weren't the first of their kind. Both types still fall under the parent category of Fuel Injection.

2. Unless you have a dyno that is A/FR meter equipped, a person isn't going to have clue one about how far out they are from correct jetting, or any idea of how much adjusting it will take to get to correct either. You could adjust all you want, but without before and after runs on an AFR equipped dyno, you are just throwing darts in the dark. Venom does have an in-house Dynojet Dyno, along with the $3000 A/FR wideband meter, and the Power Commander tuning setup on the Dynojet's PC. And it still takes time and experience to dial in a correct A\FR map for a modded machine.

You can make a jetting adjustment for every change of 250 RPM, plus those changes need to be mapped at those RPM increments over discreet throttle settings from near closed throttle to wide open throttle. This is all because the mapping for 5000 RPM at half throttle is WAY different from 5000 RPM under full throttle, as well as snapped open full throttle from 3000 RPM. You get the picture. There are literally hundreds of adjustment points that cover the injector setting mapping from all rpms and all throttle positions. So, as I said, change ANY component that changes airflow and you need different map settings.

The ATV manufacturers could certainly supply fuel injection units that are self calibrating, changing the maps themselves based on factors like:

Air Density (which takes into account altitude)

Air Flow


Oxygen content measured in the exhaust

But they don't. Their systems are just about as basic as EFI can get, and their self adjusting is VERY limited. So much so that pulling an airbox lid and pulling the spark arrester out of the exhaust REALLY stretches their capability to the end of safe A/FR ranges. In that regard, the FCR carbs currently on machines have a wider range of self adjustment than the current crop of A/FR systems on ATVs. The carb's metering can and does adjust based on mass airflow through the carb's venturi. More airflow means a stronger vacuum signal, which means more fuel will be drawn into that airflow. Not a wide range for sure, but you get the jets in a decent range for the current mods of the machine and actual airflow will change what gets metered through it to some degree.

Put more air through the current crop of EFI on the ATVs, and since there is no vacuum sensitive part to the injector's metering, the EFI just basically knows RPM and throttle opening, NOT actual airflow, so it just sprays the same amount that the map tells it to for that RPM and throttle opening until someone dyno AFR's the setup and re-writes the mapping.

Another thing: whatever "MAP" is loaded into the Power Commander module contains several hundred points of jetting to cover the grid of throttle opening VS RPM. All of those points have a huge range of adjustment when using the PC3 program on a computer, but the controls on the PC3 module itself only allow for a bulk 10% change of the downloaded base map's curve, and each control "button" makes for bulk changes to approximately 1/3 of all the RPM\Throttle control points in the base map.

So if you get the base map tuned dead on for the center point of all the AVERAGE conditions you ride in, like temp and altitude, and don't change any engine mods, you will have 10% bulk mapping curve adjustability on the controls of the PC3 unit itself.

Once again, with the current crop of basically NON-self-adjusting EFIs on ATVs, all of this is predicated on a correct base mapping as tested and tuned on an A/FR equipped dyno over all throttle settings and RPM's. Anyway, the primary focus of this thread was to address all the question "How much HP does fuel injection add to the new machines" that I have been getting.

For all the potential benefits of a high end FI system, which the ATV's do not have. The HP answer is still the same -- no difference at all.

Properly tuned CARB and properly tuned A\FR are equals for power output.

I will say that A/FR, with all its dependence on computer control, injector action, fuel pumps, and filters to save the pumps and injectors, is a far more fragile system than a simple/mechanical pressure differential metering device like a carb.

If my life depended on a particular off road engine's 100% reliability, I’d still take the carb.

The fact is that when an FCR carb is open, only the thin needle remains in the airflow path, but when the throttle body of EFI is open, you still have the whole butterfly and shaft assembly in the flow path.

If someone were to buy a Fuel Injected ATV with the systems they currently outfit them with, and never plan to do any modifications to the engine, they would be just fine. Although they would still have more weak points of potential failure liability -- CPUs that can burn out, fuel pumps that fail, electronic injectors that can stick, filters that clog, and TPI's that give the CPU bad readings. And all of those components are NOT cheap, and NOT cheap to troubleshoot either. BUT, given the fact that most people buy sport quads with the intent of making them faster, you would need to dyno a\fr re-map for EVERY single mod you do the engine, not to mention immediately needing to buy a PC3 CPU that is programmable in the first place, so it would be best to break the bank and buy everything you ever wanted to put into your engine mods and then custom dyno tune it all in on only one occasion.

So, even if the manufacturers offered better/self adjusting FI systems, they still have all the potential failure areas that were mentioned above. But the least the manufacturer's could do for sport off-road machines is offer the best of what's available in EFI from the beginning.

Venom Performance

Venom Performance

Share this post

Link to post
Share on other sites

you can get more power and atomization of fuel with fuel injection. i think it's just more convienient and easier to replace if you have problems, but more expensive too. easier starts too i think, i would buy efi over carb on my next one for sure.

Edited by oxidized_black

Share this post

Link to post
Share on other sites

Alot of that article was talking about was non programable fuel controllers though. Most of the products I've looked up say you can add maps pretty easily. Now I just need to decide if I want reverse or not.

Share this post

Link to post
Share on other sites

yes, i'm not sure how long ago that article was written, but improvements are made every 6 months or more. i would also get reverse, it's handy and a good resale option on a bike.

and i'm sure i could find an article that is a complete 360 of what you just read too.

Share this post

Link to post
Share on other sites

Well I want the reverse but it doesn't come on a YFZ to my knowledge. The newer kawi 450r has it though.

Share this post

Link to post
Share on other sites

Not speaking of atvs but cars. Todays efi blows away any carb. From easy starts to self calibration of a/f through all throttle positions. Turn the key and go is the norm. Do fuel pumps and modules go bad? yes but not often. There is hardly any maintenance on cars now. I am constantly fussing with my atv carb. Maybe i am not a carb expert but i wish atv efi was on par with automobiles.

Sent from my SGH-T959V using Xparent Blue Tapatalk

Share this post

Link to post
Share on other sites

I love carbs, but very interested in the EFI at the same time,,,,,new venture,,,and welcome Cuzco!!:wink:

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By JacobSlabach
      I have a gentleman that asked me to service his bayou for him.  I have always wondered what oil should be used in atv engines?  Pros?  Cons?  What weight should be used in what type of weather?  Is there one kind that I could bulk buy and safely used in any quad I worked on or owned?  What about performance?  Engine Life?  This has always been a 🤔🤔🤔 area for me with quads as far as why you would use one type of oil over another....
    • By JustRandy
      After looking at the wire diagram I saw the blue w/black stripe wire is coming from the neutral and reverse lights looking for ground thru the neutral and reverse switches. If it finds ground, the lights come on. The same wire also comes from the neutral relay looking for ground at the same neutral and reverse switches. So it was easy to trick the relay into thinking the engine is in neutral all the time without having the light on all the time. Just cut the blue w/black wire at the relay and ground it. Easy
      Sorry the pics aren't better

      Now it starts in any gear and indicator lights work as they should.
    • By dook
      I've been riding Suzuki Kingquad 300's for the last 20 years. I have 3 of them. I love the low gearing, low center of gravity, low rider position, low racks shaft drive and smooth ride, but they are getting old and I'm tired of fixing them. Best engineering of any utility quad, IMO, but the execution...build quality is not up to par with Honda, so the price you pay is lots of wrenching.
      I positively despise CVT type belt drives. My neighbor has a couple of old Hondas, Rancher and Rubicon and I admire the reliability of them. He does very little maintenance and they always run and have pulled my Kingquads home for me when they break.
      Is Honda the only company that makes ATV's that don't have CVT? I like the build quality but I don't like the high rider position caused by the vertical cylinder, the cold nature of them, having to warm up for several minutes and the plastic skid plates. I guess all modern ATV's have the same issues, though (correct me if I'm wrong).
      Been checking with the dealers, it seems Honda foot shift models are scarce. I really don't need devices/gadgets to decide which gear I need to be in. So I'm avoiding the DCT models. I must have IRS and EPS because of my age and physical condition though.
      Is it possible to get a Rancher with IRS, EPS and foot shift? The specs I'm reading show the rancher is 2" lower than the Rubicon. I'm assuming that to be seat height. With vertical cylinder design, the more you grow the engine, the higher you push the seat....at least that's my thinking.
      Any comments from the Honda experienced?
    • By spock58
      I was reading another forum recently about fuel leaks and possibility of fire happening. Reminded me of an incident I had a few years ago while working at a Can Am dealership. The quad was a stolen & recovered Outlander 650 that had been tampered with. These quads have an electronic safety system, similar to their DESS system on the sleds. You cannot bypass the key switch and get spark without a computer with factory software. Anyway, I was trying to determine what was damaged since the thief had attempted to hot wire various electronic parts. I got all the extra wires removed and things looked back to stock. Pulled the spark plugs and was going to check for ignition and if the starter still worked. Well, they both worked alright and guess what - the cylinder was flooded with fuel! Instant flames with gas spraying all over...great!! I managed to use my hands to put out the fire, good thing I had on gloves (but choked they were ruined of course, haha). Seems it's possible to flood an engine with efi when you put power straight to the injectors, doh! As in much of life, you cannot take things for granted (I'd only seen carbs flood like that). And even though it had spark, the quad still needed a new ECM to run - that part alone was $1200. So lets hear your stories, crazy stuff happens every day I'm sure.
    • By Dra O
      posted a while back - it was running at one point - I have all the plastic shroud off - it's down to frame and engine now
      -fuel pump: when line from petcock is attached, no fuel comes out other side to carb; the line to the carb is open (can blow through it); I thought when I cranked engine that the pump would spit out fuel on other side but it does not; I removed fuel pump and opened it up - diaphragm looks good - but internal areas had lotsa calcification build up - I cleaned this out and dried it good - the clear plastic pieces (?diaphragms) aren't broken - the spring w/ steel ball on end moves freely; am putting it back on tomorrow; but can anyone answer about the pump? isn't it supposed to pump fuel through it... to other side... to carb? puzzling
      -along with fuel pump: I replaced petcock 3 weeks ago (gas tank had rusty fuel in bottom - cleaned it out prior to new petcock); when I turn petcock arrow NOT to on or reserve, fuel comes out of line; when I turn it to on or reserve, fuel doesn't come out; puzzling
      -I don't know what's on back of fuel pump - it's a valve that has a hose coming out of it - looks like it goes to engine/carb - I haven't traced this out yet - what is it?
      -can squirt gas on air filter and engine will run for 2-3 seconds then stop - fuel in top of carb (under diaphragm) does same
      -it likely needs carb rebuild - will get to this - but something isn't allowing fuel to get from fuel pump to carb
      -I THINK it has a mikuni model x carb - diaphragm is ID 26mm  OD 68mm - hard to find inexpensive diaphragm, I guess because it's a model x
      -last thing - I replaced solenoid due to old one clicking; I HAVE to be charging the battery or it won't start/turn over - battery just goes dead; but if charging, it'll turn over nicely; i'm guessing it's a bad battery
      -any help appreciated - I've never owned an ATV before - inherited this beast from grandparent in-law
  • Similar Tagged Content

    • By Hayden Pahnke
      Bought brand new petcock and carbetator, turned air fuel needle out 2 turns and machine still acts like its starving 4 fuel on top end. Any ideas?
    • By Brad Leeson
      What's going on party people? First, thank you for allowing me the opportunity to be here. I recently purchased a 2005 yrs 450 and have yet to run the bike at full throttle. The bike fires up, idles, seems like everything runs fine except a little popping when you let off the throttle or until you hit 5th gear. It runs strong; no bogging or sluggishness until you hit 4th gear and open it up. Then it begins to act like it's out of gas or the about to be out. I can pull over and sit for 5-10 min and it runs strong again until you open the throttle. I have the carb off the bike to clean and wrote down a list of factory and what I found installed. I also listed other key factors and hope someone can help and explain. I'm new to the scene and have no prior mechanical experience but my theory is worst case scenario I have to take it to the shop anyway so why not learn. I actually enjoy it. Lol. Thanks a million. Hope to get back on the trails soon. 

    • By Paul Maple
      I have a 1999 Sportsman  500, it was running fine, than started to lose power in the winter, I adjusted the idle screw and away I went, than a few weeks ago it died, I have found that i am flooding the engine, compression was at 70PSI and due to the compression release mech. i assume i am good as it compared to the same PSI on a 2000 sportsman 500 i have. i cannot start the atv unless i go full throttle and it starts an runs for about 30 sec than dies, again it is flooded. i ordered a new carb off ebay as i could get one for around $40. put that in same issue, i have checked the timing, (good), valves out of adjustment i adjusted to .006 still same issue, i have found the exhaust lobe and rocker arm to have some wear, i have ordered new ones, but am looking for any other input in this area as well. would the exhaust cam and rocker arm cause the engine to flood? i have used a bore scope and the piston liner has good cross hatching still? any input would be great.
    • By Resurgence Small Engine Inc.
      This past spring, Jonathan worked on a 1991 QuadRunner 250 that came with the fuel pump removed. We didn't find good information about connecting it online, so we made a video.
      Below is the link to watch Jonathan describe the connections on the Suzuki fuel pump. This applies to both the Quadrunner and King Quad ATV models.
      Hope you find it informative!
      Resurgence Small Engine Inc.
    • By jnahnet
      Fuel line hose has a pinprick hole. And tips, suggestions or warnings about how to change it out would be appreciated.

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Create New...