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  1. #1

    Default Interchangeability between 2003 Dual Carb 2-stroke 115 and Carb'd / OX66 FI / HPDI 150's?

    Good day all,

    My boat is powered by a 2003 Yamaha 115 2-stroke, dual carb, code 115TLRB. Has been a great and reliable motor, but is a bit underwhelming in terms of power. I'm considering upgrading to a 150 of the same vintage, under the hopes that I can maximize interchangeability.

    What's the easiest path? From just basic parts diagrams, I've been able to discern that common stuff like the steering linkage seems to be the same between at least the carb'd 115 and 150 outboards. But I'm concerned how deep it gets when you start talking engine harness plugs, or if going to EFI 2-strokes like the Vmax, ECU/Fuel pump etc.

    There's actually a very, very nice 2000 OX66 Vmax FI 150 for sale locally, that I have my eye on. Code VX150TLRY. Guy says all the FI stuff, including fuel pump and ECU, are under the cowl and I'll have no issue swapping - direct plug and play. I have my doubts.

    Can anyone point me in a general direction here? Should I stick to finding the equivalent base model carb'd 150 and avoid complexity of the OX66 or HPDI 150's?

  2. #2

    Default Re: Interchangeability between 2003 Dual Carb 2-stroke 115 and Carb'd / OX66 FI / HPDI 150's?

    Why the doubts?

    Disconnect the 115TLRB (control cables, fuel hose, ten pin harness, battery cables, trim/oil harness if installed, etc.) and then unbolt and remove it from the boat. Install the VX150TLRY. Reattach all of the disconnected stuff. Install a different propeller.

    You are now ready to go.

  3. #3

    Default Re: Interchangeability between 2003 Dual Carb 2-stroke 115 and Carb'd / OX66 FI / HPDI 150's?

    Hey Boscoe, thanks for responding, I appreciate it.

    Why the doubts - I guess that's what I was getting at, I just don't have the knowledge firsthand yet to know whether it's a simple plug and play or not with respect to the harnesses. I've pulled my share of car and motorcycle engines over the years, but I'm new to outboards. I can answer the easy stuff - need to match shaft length (20"), is the weight/hp of the new outboard appropriate for the boat, etc. But I just haven't had my hands on enough of these outboards or their harnesses/controls.

    Your feedback seems to indicate it really is plug and play simple. Looks like that 10-pin has leads for tach, engine stop, trim, starter, etc. So it sounds like all that is standardized then? That's great.

    Do the FI/HPDI motors require the same single low pressure fuel feed line from the tank to the motor, and a prime bulb, same as the dual carb 2-strokes? No high pressure fuel pump in the tank? No return line? I'm ignorant here.

    With respect to the controls, you're saying that the linkage hookup for shift and throttle on carb and fuel injection is really identical, despite that part differences? My throttle connection goes to the magneto lever. I certainly assume there's no magneto lever on the injected motors, and the lever hooks up to a throttle body instead. Is it still directly interchangeable? What about the throw distance of the controls - is that also standardized for Yamaha's?

    These are things I'm just not sure on, but they may have easy answers.

  4. #4

    Default Re: Interchangeability between 2003 Dual Carb 2-stroke 115 and Carb'd / OX66 FI / HPDI 150's?

    Yamaha has it all thought out.

    Fuel supply is the same. No return lines to the tank. All done on the motor.

    The throttle cable end fitting connects to a pin on the motor. The motor either has a magneto lever or not. Does not matter to the throttle cable. Same with the shift cable.

    All of the larger HP Yamaha models use a push to open throttle mechanism.

  5. #5

    Default Re: Interchangeability between 2003 Dual Carb 2-stroke 115 and Carb'd / OX66 FI / HPDI 150's?

    Thanks for all the info. Huge help. What service Manual is this out of? I have one for my 115 but I don't recall seeing anything like this schematic in it.

  6. #6

    Default Re: Interchangeability between 2003 Dual Carb 2-stroke 115 and Carb'd / OX66 FI / HPDI 150's?

    Not from a service manual. From a Yamaha rigging guide.

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