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R1 Exhaust Change

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by norafugengixer, Aug 8, 2010.

  1. Hi all.

    A mate of mine has an '09 Yamaha R1 and he has just fitted a set of Yoshimura cans and mid pipe (eliminates cat).
    Since fitting the system the bike apears to run slightly lean. Some popping on deceleration and the smell of a lean running engine.
    Normally i would fit a power commander or have the stock ECU re-mapped however the bike is fitted with an oxeygen sensor.
    Isn't the job of the oxeygen sensor to tell the ECU if the engine is running lean or rich. So therefore the bke shouldn't need re-calibrating.
    Anyone have some insight?

  2. the 09 pops heaps with the yoshis and Y pipe. Only way to stop it is smog block off plates, but wouldn't even bother. Plenty have been running this way since new.
    Even PCV won't fix the popping, just tame it a touch.

    Mine runs quite ok without the PCV, waiting for a new version to come out tho.
  3. More open cans will be more likely to carry on, even if the mixture is right. So it may be fine.

    As to the O2 sensor automatically fixing the problem, the answer is "yes and no". If it is a completely closed loop system, then yes is should fix the problem, but most factory systems are not. They use look up tables and thus there is a limit to how far they can be adjusted.

    So it may be OK or it may not be. You need to tap into the O2 sensor and go for a run to be sure.
  4. from my understanding, the o2 sensor is only used when the bike is in closed loop mode... and this is usually only at idle, warm up, and at very light throttle application. once the throttle is opened up more than a certain amount, the bike will run in open loop mode, that means it is running soley off the fuel map, and the o2 sensor isn't in the equation. you might want to get this confirmed tho... but your local yamaha dealer probably wont know so maybe try researching on the net, the R1 forum is a good place to start.

    be careful the bike isn't running too lean. most bikes are usually tuned lean around the EPA testing RPM's (approx 4500-6000rpm, known as the EPA dip) to aid in emission testing. by fitting free-flowing pipes you can lean it off even more in this area. my 04 R1 was very lean around the "EPA dip", and we added 25% more fuel in said area to get the air:fuel ratios back to where they should be.

    smog block off plates will stop the injection of air into the exhaust, and eliminate some of the carry on, but they may not completely stop it. does save some weight tho, and the 09 R1 is a bit of a brick so every bit helps :)

    the best (and only way) to know for sure, is to get it on the dyno for a diagnostic session. around $100 from most places. they will check all the throttle positions from 0-100% and check the fueling. it's worth it for peace of mind, and cheaper than a rebuild.
  5. Cheers everyone.
    I think a dyno run is in order.
    Better to be safe than sorry.