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Yamaha YZ450FX Fuel Line Improvement Mod


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!

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