Jump to content

Yamaha YZ450FX Fuel Line Improvement Mod


ktm300dude

Hi guys, i watched what Dave Simon from ktmhusky youtube site did to the Yamaha YZ250FX fuel injector to improve low rpm response, cure the lean out issue, and stop flame outs and stalling at low rpm. Very interesting I thought, so i pulled my 16 YZ450FX apart and checked out the fuel rail and i's exactly the same. It has a sharp as 90 degree bend right on top of the injector and another sharp as 90 bend about 4 inches upstream. Not cool at all.

I have done what Dave did by getting an engineer to make a new straight shot injector top, but I had a 8mm tail with a barb made on mine so That I can use a bit of 8mm fuel injection line to push onto it and use a hose clamp to secure it. Dave made his so he still clips onto the stock 90 degree fuel fitting. I have made mine better than that to get the best possible fuel flow. I found 8mm steel fuel line on an old wreck of a car I have, a z32 300ZX with almost the perfect bends for the job. So, the injector now has a stainless steel top made with a straight up 8mm tail with a barb. The steel fuel line joins there and it goes up and then curls over like an upside down U-shape with nice curved bends (no restrictions). It then turns 90 degrees nicely and goes towards the right side of the bike. From there it curves nicely 90 degrees again and goes towards back of bike with a barb on it joining it to the stock rubber fuel injection line that goes to the tank.

There's about 40 or 50mm clearance between top of injector and the bottom of the airbox, so just enough room to do it. My steel fuel line under the airbox is almost touching, but apart from that, it's an awesome install and i love it. My YZ450FX never stalls now! I was lucky enough to find the right shape fuel line, bending it slightly to make it perfect. Apart from finding a steel line off a car, I'm not sure if an Engineer could fabricate an 8mm steel line to do the job. Because it's a fairly tight upside down U shape that goes to the injector, rubber and braided lines likely won't be suitable. Dave Simon from ktmhusky is onto something big with fixing four-stroke fuel systems. The stalling and flameouts that I experience with my YZ450FX aren't something we have to live with. It wasn't bad, but now it's just perfect in the woods. This is a cheap and awesome mod!



User Feedback

Recommended Comments



Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


  • Similar Content

    • By celler
      I sold my bike and have parts to sell:
      Rekluse Core EXP 3.0 - 20 Hrs on New EXP ring and Yamaha fiber plates, 130Hrs on remainder. Full clutch and side cover.  Spare set of EXP weights. $400
      Seat Concepts comfort seat. Good condition $100
      Yamaha Rear brake disk. Very little wear. 20Hrs on disk. Straight. I replaced with a solid disk. $30
      Yamaha Starter Relay and starter brushes - $15
      Misc small parts - Free to whoever buys over $20 of goods
       
      All prices include shipping in the US.
      Text me for more information or pictures.
      Thanks for looking.
    • By BDTRENT
      Selling a complete GYTR radiator cage from my YZ450FX. The cages have roughly 50hrs.

      These will fit the following bikes.
      WR250F(2019, 2018, 2017, 2016, 2015)
      WR450F(2018, 2017, 2016)
      YZ250FX(2019, 2018, 2017, 2016, 2015)
      YZ450FX(2018, 2017, 2016)
    • By Timo2824
      Picked up a new bike today! Can't wait for the ground to dry out so I can checkout the tuning app.

    • By Desert_DRZ400
      Hello all, I currently have a 2016 drz400s and have done all of the necessary mods to make it perform the best.  I love the capability of a dual sport but I find that I want something a little lighter and more powerful. I do have a truck to haul a dirt bike so no need to ride to the trails, that being said it would be nice to make my next bike street legal if I wanted to (short commutes, no longer then 10 miles with a 50 mph max speed limit, I also have supermoto wheels/tires). 
      I live in AZ, my average pace on the trails is between 15-30 mph.  Never got the drz over 65mph on the trails.  My rides last between 1 and 4 hours usually max 60 miles.  I'm looking at the yz250fx or the yz450fx.  I am 6'1 and 220 before riding gear.  I've read through the forums and watched all of the reviews on Youtube about both bikes, however I am still looking for answers.  How is the fuel range on the yz450fx?  I believe the yz250fx varies between 50 and 70 miles depending on how hard you ride.  Me being a bigger guy will I want the yz450fx?  Coming from a drz400 which mine has around 35 hp after my mods will the yz250fx feel the same power wise or will I want something more? 
      I keep hearing the 450 will be a handful but I'm wondering if that is something I can get used to and learn.. plus with the mapping can I temporarily detune it?  The only thing that tires me out on the drz is having to pick up up if I drop it.  Both the yz250fx and 450fx are considerably lighter.  Also what is the life of the engine?  I have 1500 miles on the drz, not sure what that is in hours.  How many miles/ hours for oil changes?  Based on the information above I need help deciding which one.  Thanks! 



    • By Bryan Bosch
      POWER, TUNED TO PERFECTION
      Same DNA as the class‑leading YZ450F, with a bigger fuel tank, electric start and power tuner smartphone app that lets you adjust your bike's settings to your specific style and conditions.
      GNCC®/Hare Scrambles Focused Racer
      All new for 2019, YZ450FX™ is based on Yamaha’s flagship motocross model—the YZ450F—with many added features and unique settings that make the YZ450FX the ultimate GNCC®/Woods racer.
      Yamaha Power Tuner App
      Yamaha’s exclusive Power Tuner app puts the flexibility and precision tunability of the GYTR® Power Tuner into your smartphone. Make fueling and ignition timing changes instantly and upload them to the bike via the onboard WiFi system for the ultimate in track-side tuning.
      Electric Starter System
      Utilizing a compact starter motor and ultra-lightweight lithium battery, the YZ450FX maintains the convenience of push-button starting, for effortless restarts under pressure, and relaxed riding when the clock isn’t ticking.
      Potent Fuel-Injected Engine
      A high-compression cylinder head, forged piston, aggressive cam profiles, cylinder geometry and much more work together to give YZ450FX riders the ideal power spread in challenging GNCC® racing conditions.
      Advanced Alloy Frame
      Yamaha’s bilateral beam aluminum frame features main spars, FX-specific engine mounts and an engine mounting position that centralizes mass and provides an ideal balance between cornering feel and straight-line confidence.
      Class-Leading Suspension
      Yamaha uses KYB® spring-type forks on all of our YZ® models, with industry leading function and easy set-up at the track—these fork are ready for the top step of the podium straight out of the box.
       
×