Turbo Yamaha Nytro MTX build thread

Lococoin

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ready to ride yet?looks good!how much boost on premium?

I deleted my old answer to your post woodie and am adding more info:


I did get a chance to take it to Golden on the 22nd. The fuel mapping was not sufficient for me to do much playing so I went home and contacted Dave at powderlites. This sparked him to re-evaluate the mapping and to get a new map made up within a day or two. I cant say enough good things about Dave and the guys at Powderlites. I love how they always answer the phone, in fact Dave was helping me on the phone teaching me some tricks about the RB3 software late on a Sunday night. Unfortunately I am now back up at work so i cant test the new settings. I do have a copy of the pro software now so I will be able to make my own adjustments. If i would have had that software when I went to Golden, I would have been able to tweak the map and make it work. Without it my hands were tied so I went home to double check if I had an install problem.

Daves map is setup to start running on the RB3 mapping around 2 lbs of boost. In vacuum the sled runs rich(IMO), but its supposed to be running on the stock Yamaha mapping so if the fuel pressure is close to factory spec(46.1 lbs) it should run like factory. I talked to another guy running the mcx and he had rich numbers in idle too so its got to be like that from the factory. If that is indeed the case, I will either adjust my CO settings to try and bring the air fuel numbers up to something I find acceptable, or I will build my own RB3 map that can pull fuel out in the vacuum columns. Having a sled running 12:1 or richer in part throttle is unacceptable in my mind. You can increase your fuel economy and your throttle response by fixing that, and that is what I plan on working on.

The next issue is the size of the Nytro injectors. I have been told they are a 330 cc injector and will run out of fuel around the 280 hp mark(13 lbs at 1500 feet elevation according to powderlites). I hate running my injectors over 80% duty cycle for extended periods of time, so I may start looking at some other options to help bring it more in line. The problem with bigger injectors is that part throttle tuning gets trickier.

I am not looking to make a huge HP machine, hell i can barely ride this one at 10 lbs. I also don't want to be spending 200 a day on fuel for race gas, i just want to make sure I have as safe of setup as possible so that I don't have any engine failures.
 

Washy

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I will have to hook a wideband up to a stock sled an see what the A/F is like. I am guessing the headshim has a little to do with the Rich condition a little as well. The stock sleds run better at idle than one with a headshim.

I removed 10% fuel at idle to get to 13.5-14 to 1 ratio at idle and 25% fuel at 2000 to 3000 up until engagement to get 13 to 1. Not enough snow to tune past that. Really rich in this area.
 

Lococoin

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I will have to hook a wideband up to a stock sled an see what the A/F is like. I am guessing the headshim has a little to do with the Rich condition a little as well. The stock sleds run better at idle than one with a headshim.

I removed 10% fuel at idle to get to 13.5-14 to 1 ratio at idle and 25% fuel at 2000 to 3000 up until engagement to get 13 to 1. Not enough snow to tune past that. Really rich in this area.

That would be great if you could get some stock wideband numbers.

How are you pulling different amounts of fuel at different rpms? Using your power commander?
 
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