stock exhaust mod?

Different maps do not help, the problem is that the ECU runs closed loop in a certain rpm range that means it adjusts the fueling depending on the O2 sensor reading. While that works well with the O2 sensor plugged into the ECU it creates problems when you block the O2 sensor because you want to use the PCV and do not want that the ECU changes the fueling to compensate for the PCV adjustments. At high temperatures it works without flaws but fails at low temperatures. Somehow the ECU adds to much fuel when it is cold and that seems to be adjusted by the closed loop operation.

Autotune would be a possibility but that would mean that the pcv had to correct the fueling very much and autotune would have to run in closed mode all the time. I am still not sure how to set up autotune so it does what I want the description on the DJ website is not very helpful and thus I did not buy it.
In addition I realized that the bike is not running so well anymore (since adding the PCV) when at high altitude (8000 feet and more). This might be related to air pressure compensation of the ECU. I am not sure how to adapt the auto tune to use the air intake pressure and compensate for the altitude. Well in principle one could make a fueling cube depending on intake pressure, outside pressure and temperature but the PCV only allows a 2d map.
Again it should not be difficult to add another dimension but I am not sure that Dynojet will do this. Anyway it is a bit frustrating that there is no easy way to have an always nice tune just taking the PCV and autotune. It would help if Dynojet would describe in more detail the possible wiring and programming features on their website. Most information you have to find yourself but some (W-Beast and SoCalRider) did this and found their way to use it. I just have not enough time to try it myself, too busy riding ;).
 
:funpost: I hear you guys that live in the US that have to adjust for altitude and variations in temp. I live in the UK where I don't have to account for that, as the weather is crap all year round, and its pretty flat! :)
 
Don't assume you will lose power down low. I have modded my bike with full exhaust, PC3, 16T front sprocket, cut air box and his flow air filter. My bike picked up noticably starting at 4000 RPMs. When I first started with the mods, I did the free mods and removed all the cats and used a long sharp steel rod to punch a hole all through the stock inner baffles. It worked, but it still weighs over 15lbs. I replaced it within Ixil Extreme Black Shorty slip-on. I really like it, but switched to the Yoshimura TRC that came with the headers. The headers did the most for the lower RPMs, but it was my last addition.
 
Just buy a cheap used can and rework it to suit. They are often free, since no one wants to offer much or pay for shipping. This way, you can experiment without loosing the ability to put things back to stock if like it. You also have little down time.
 
bigbaddave43 said:
Just buy a cheap used can and rework it to suit. They are often free, since no one wants to offer much or pay for shipping. This way, you can experiment without loosing the ability to put things back to stock if like it. You also have little down time.
Click to expand...

:tup: :tup:

This is exactly what I did with the header and CAT. Bought a header with the CAT in-tact to sit on the shelf then proceeded to knock out my CAT. But I can go back to stock.... Best plan to have.
 
There is plenty of info on this site and the other one about modifying the GenII for performance. This bike has been around for eons . . .If you search and read up you will find that with proper mods there is nothing but gains to be made in both performance and driveability. You are worried about loosing bottom end grunt? A well modded GenII will make more power than a stock one from as low as 3krpms. By the time you reach 7k you are making around 25hp more. A full exhaust system like the Yoshi will dramatically fill in the stock bike's 7k dip the power curve. The stock exhaust system is a packaging compromise with short tubing to fit the catalytic convertor and is a major culprit in the midrange dip in power. The corked up muffler is another culprit. Basically if you really want to improve both power output (throughout the rev range) and driveability, you should not be afraid to mod the GenII. It responds shockingly well to the right upgrades . . . .That said, fuel mileage on my "full package" gen II isn't great but it is liveable. I average around 35mpg.
Here's a good old thread for you to look at: Full Yosh system tested-dyno charts - FZ1OA Message Board. Here's also one of Ivan's dyno charts showing stock vs modded genII (this one does not include the Full exhaust system and you can note the mid range dip in both plots . . .)
 

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There's quite a difference there in the graphs! I'll have to do a bit if pricing up for parts and do a bit more studying. Looks good to me. Thanks guys.:unworthy:
 
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