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Discussion Starter #1
I have a Boulevard C90 2005 with aftermarket pipes, a K&N air filter and a Dynojet PCBIII Power Commander.

The bike seems to burn rich. It does not like stop and go traffic conditions, backfires when you idle down a hill on occasion and has been known to cut out once I open the throttle to pull off from a traffic light if I have been idling for a while. The map that is loaded on the bike since I got it with the modifications described above already in place, was pretty much a default map that the notes indicated was for a stock filter and stock pipes. Over the winter I tried loading a few different maps using after marked pipes and after market air filter, however that did not seem to make much difference to the performance of the bike in the traffic this year and on the on occasion when accelerating hard, I noticed the bike would splutter and die back and then sort itself out once I released the accelerator a bit. In the cold weather I have noticed the bike spluttering as well. With the dense air I would have thought that if the bike were running rich, that the cold wet air would have helped, not made it worse.

As the maps did not seem to really have any conclusive affect on the performance I loaded the original map back onto the bike and have left it like that. I have put up with the spluttering and backfires but it bothers me as I felt there was something wrong and the bike should not be that sensitive.

Last week things went suddenly worse and the symptoms became exaggerated. Opening up the throttle while riding at speed resulted in what seemed to be a miss fire on one or both cylinders (?) and then pulling off at a traffic light would most often result in the bike cutting out. Even light acceleration resulted in mis-firing. Starting the engine again would result in a back fire and it did not want to start very easily.

After the bike cooled down I tried starting it again and now it's idling about 500 RPM faster than normal and a slight acceleration to change into second gear when riding down the street would result in a mis-fire and spluttering.

I took the plugs out and noticed that the front cylinder plug was pitch black and sooty, not wet but covered in soot. The rear cylinder plug was black and sooty at the base and the thread was dark but the tip of the plug was burnt white. I am not sure but it might have seemed that it was too white and indicated that the rear cylinder was running very hot.

I had initially thought that this bad behaviour was as a result of the PCBIII not being mapped correctly. But now I am wondering if there could be something else wrong. I had replaced the plugs when I changed the oil in December so they should not be a problem, maybe one of the plugs I put in was bad to start with?

Perhaps there is something wrong with one of the injectors?

I'd appreciate any thoughts anyone has on the above. Any ideas on what the problem could be and also if anyone has some knowledge of how the maps can affect the performance would be very helpful.

Much appreciated.
 

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Discussion Starter #2
For anyone interested in a solution to the above.

I replaced the plugs to no avail. Obviously not the problem.

Looking further under the air filter I happened to notice that the rubber hose that was attached to the lower part of the air intake manifold was tightly mounted, but the clamp seemed to run off at an odd angle. I then realized that the rubber hose was actually buckled under the clamp, exposing a gaping hole, thus allowing air to pass into the intake of the rear cylinder.

Apart from the fact that unfiltered air is passing into the rear cylinder, I imagine that this would severely unbalance the two cylinders when it comes to air/fuel ratio. I would imagine this would result in the rear cylinder getting more air and therefore burning hotter that the front cylinder. Im not a mechanic so anyone who has a better explanation please do correct me.

The bike had been serviced by a dealer at the time that I purchased it and I suspect that the dealer did a poor job in re-assembling the bike, and this would explain the rough running I experienced which was exacerbated by very hot days (like on Friday) and very cold days like in early spring.

Put the bike together and it's running smoothly and sound a lot better. Will see how it goes when it gets hotter.
 

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I have the same power commander but what i didnt see is did you put the timing retarder module in you bike and also did you block off you pair valves with the power commander you should do both
 
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