Before I get into this discussion I feel I should mention that the 2006 and the 2007 S2R1Ks are different. Initially I thought it was just the check engine light. Removing the O2 sensor on an 06 does not trigger the check engine light, but it does on the 07. Then after many discussions with other DMFers I now belive it's a little more than that. For example, NAKID recently installed a Dynojet PCIII on his 06 and has been having good luck with it with just the O2 sensor removed. I know of someone who's tried that on an 07 and it didn't work. It did at first but after a few hundred miles, the bike started running like crap. Going back to the dyno and redoing the map made it run good again, but then after a few more hundred miles it ran like crap again. I think the bike/ecu does some sort of test and when it finds the O2 sensor is faulty (or in this case disconnected) it changes the fuel map. I guess we'll need to stay tuned to see what the long term effects are on NAKID's bike, but from what he told me last week, it seems to be running great.
Now onto why I started this thread.
As many of you know I have been pretty active here and on TOB trying to find an acceptable solution (other than spending $1200 on a DP ECU) to the poor throttle response/surging issues with my 07 S2R1K. As stated above, I had a check engine light after I removed the O2 sensor. I could have dealt with the light but the bike never seemed to run as strong with the O2 sensor removed. The surging was gone but the lack of power was discouraging to say the least. I did find some of the lost power by backing out the air bleed screws to make the bike run leaner. I kept backing them out and the bike ran stronger and smoother but once I got to a certain point, the idle would increase to over 1500 rpm which wasn't acceptable.
Last year in an effort to find an inexpensive solution I bought a Rapid Bike O2 emulator from Wild Bill @ Rage Moto. He had purchased it for his S4Rs and then decided to go a different route so he gave me a deal on it. I installed it on my bike and reset the ECU by disconnecting the battery and then took it for a ride. The bike seemed great for about the first 40-50 miles or so and then the check engine light came on and then when I would roll on the throttle the bike started bucking so bad it almost launched me off. I pulled over and turned the bike off and then restarted it and continued on my way. A few miles later I encountered the same problem so I carefully (and slowly) rode to my destination which was only a few miles away. When I arrived I disconnected the battery and removed the Rapid Bike O2 emulator. The ride back was pretty uneventfull and the bike rode as it did before with the O2 sensor removed.
A few weeks ago I reinstalled the O2 sensor just for laughs and the bike responded by reminding me how much more power it had with it connected. I have been riding it since then with it connected although I have been getting tired of the surging and popping/backfiring on decel. I tried to tune it out using the air bleed screws and removed most of the popping/backfiring but it was still present during decel from high RPMs.
I had decided to just live with it until last week when I found a thread on another board (don't worry, not TOB) regarding a DIY O2 sensor eliminator.
The basic idea was to install a 330 Ohm resister in place of the O2 sensor. From all the feedback I saw in the thread it seemed to work for them so I thought I would give it a try. As some of you know, I can be a bit anal about my bike and I really didn't want to just stick a resistor in the end of the plug and be done with it. The thought of that and wrapping it with some electrical tape just wasn't an option so I thought I would use the connector from the Rapid Bike O2 emulator and solder the resister to the wires coming off of that and then shrinkwrap the whole thing for a nice clean look and to seal it from moisture.
Before I chopped of the end of the emulator I took my multimeter to it to see if I could determine what exactly it did. To my surprise measuring the resistance yielded a resistence of guess what...........
Wait for it..........
..........330 Ohms!
I was a bit surprised and disappointed as I thought that if it measured 330 Ohms, why bother trying the DIY trick I had found. That is until I remembered the ground wire on the emulator. I'm not sure what the emulator is supposed to physically do when you plug it in but what ever it is, it becomes an active circuit when it's grounded and plugged into the bike.
Not really expecting anything groundbreaking I decided to plug the emulator into the bike without grounding it to see what kind of results I would get. So basically it was just putting the 330 Ohm resistor inline like I read in the thread. I went through all the normal steps and disconnected the battery before plugging it in, waiting for about an hour and then reconnecting the battery.
As soon as I thumbed the starter button I knew something was different. Normally it will start right up, but it would take a few revolutions for it to fire. Not this time, it fired up without any hesitation, almost before I released the button.
Not to mention how smooth it was while it was idling.
Ok so now for a test ride. I let the bike warm up as I put on my gear as I always do and then took it for a short ride. The bike ran flawlessly. I was a bit skeptical at first because of all the problems I had with the emulator last year but I have about 200-250 miles on it since with a bunch of key cycles and I've still not encountered any issues. No surging, no popping or backfiring on decel, nothing. I can even ride the bike at 3K rpm's and it's smooth unlike before when it shuddered and shook at any rpm under 4K.
All I can say is this is the best, most cost effective solution for any of you who are experiencing the surging issues and the popping/backfiring on decel. A simple 330 Ohm resistor is all you need. I plan on putting a about another 150 miles or so on it tomorrow. I'll check back in and let you guys know if there are any problems.
