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Running better than ever!

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CBR >> Past CBR Models >> CBR 1100XX "Super Blackbird" >> Running better than ever!

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Running better than ever! - 8/18/2007 4:05:23 PM

Flickthebird

Posts: 11
Joined: 7/6/2007
Status: offline

   I bought my '98 bird a couple of years ago from a friend of a friend. The bike was stock except for an Erion Racing exhaust, a stage one jet kit, and new irridium plugs. It seemed to run very well although when hot, it would "cough" occasionally at idle and had slight off idle hesitation that I attributed to the header. I removed and thoroughly cleaned the carbs and adjusted the idle circuits per the manual but the problem persisted... Any ideas?
A month ago, I noticed one cylinder seemed reluctant to fire when starting (in the morning) but cleared by the time I turned off the choke. The next morning the same thing, but this time, the "dead cylinder" wouldn't clear. By the time I returned home (about a mile, round trip) it was running on two cylinders! I shut the engine off and began to look for signs of tampering or damage, but found none. When I tried to restart, the motor cranked slower than normal, so put the battery on charge. My first thought was a spark-plug had failed. But TWO plugs within a day of each other??? No way!   Figured it out yet?
When the battery was topped off, I tried again. Nothing but an incredible backfire out the tail pipe! I pulled the plastic, tank, and airbox to gain access, and began checking everything I could:

1.   The first problem I noticed was the wires going to the rectifier / regulator looked burnt (then I remembered I had been stranded once before as a result of a rectifier wire corroding off. I had to do a quickie roadside repair that seemed to be fine... until now!). The culprit seemed to be the rear tire of all things! When I replaced the rear tire I up-sized to a 190, and that extra width rubbed a small hole in the fender, just in the right (or wrong!) place to allow water spray from the tire to "wet" the rectifier wires every time I hit a puddle! As I contimplated the repair to the wires I realized the male plug that mates with the rectifier had been removed by the previous owner! The wires were terminated with cheap "crimp" terminals and plugged directly into the rectifier. This aggrivated the water spray condition as the ternimals had no protection at all. Additionally, the heat produced by the degraded wires caused the terminals of the rectifier to "lean over" to the point that two of the stator wire terminals touched, effectively shorting out the stator and allowing the battery to discharge. The lower voltage caused the next problem to rear its ugly head...   Guess what?
2.   As I checked the ignition coils I found that one had secondary resistance of 145,000 ohms when read from plug wire to plug wire ( spec. is 32-34K ohms). The manual states further disassembly is required to isolate the faulty component. After removing the ignition leads, the coil tested good. Next, I removed the plug boots and the ignition leads tested good... The plug boots contain a removable 5000 ohm "supressor" resistor for some reason but they tested good too!  The last piece of the puzzle was the plug boot itself. The 90 degree metal piece inside the rubber boot had cracked or otherwise failed and had a resistance reading of 105K ohms when it should have been 0! This part must have been broken before I bought the bike and the resistance slowly increased (probably due to corrosion) untill finally with the reduced available voltage from the discharging battery, both plugs on that coil quit firing (I'm not sure why both?).

The fix:
1.   Purchased harness repair kit on Ebay for $3. It included new male plug and higher quality brass crimp terminals (that I soldered also). Fortunately, there was enough extra wire on the pigtail to allow removal of all damage with no splicing n