I swapped this fzr 1000 exup 1993 for my motor from a Gypsy about four days ago... It has been hacked into some semblance of a street fighter... except it has no.. speedo, rev counter, temp gauge, working lights... When i rode it home the first ten minutes took my breath away... loved it.. the rest of what turned out to be a 50 min journey timefor 20 miles was very dissapointing. I have just read an article written by a fellow yamaha (not fzr) rider which is so exactly what happens when i ride my bike that it's riduculous... EXACTLY the same symptoms.... Two of my plugs are well sooty and coked (plugs 1 &2) the other two are optimal (3 & 4 light tan)... Start off riding my bike everything is heaven, (if i dont increase the load and just poodle, will keep performing well) as soon as i start putting a bit of load thru it, using more of the rev range or higher speed dual carridgeway stuff, i get exactly the same as this fella... I checked the sparks and they all seem similar... is it poss that my left coil is dying and when under load and getting hot? starts to struggle.. therefore not burning the mixture properly.. hence two very sooty/coked plugs??? could it be the CDI ignition ignitor, does this get hot as you start going a bit quicker???? These symptoms seem very specific and the contrast between the plugs is very definitive, there is probably an obvious answer? If you are a bit more clued up than I am about the Yammy. I have included this guys description of the fault, I couldn't have captured it better myself.. [color="#FF0000"][/color][color="#FF0000"] Here's the story so far...[/color] Buy the bike with about 43,000 miles on it at a local shop here in Tucson. Looks and sounds pretty good, but it's got rather loud, after-market pipes (definitely not Cobras or Jardines but maybe HG Krome) and a battery that has been sitting too long. Ride it home. After about 10 minutes, I notice a "miss" in one or both cylinders, at both highway and city speeds. Gets worse as I ride. My first guess is that the battery is preventing the ignition from putting out a good spark. Remove battery and notice fluid in all cells is below the plates. Refill with distilled water, and trickle charge the battery for a few hours. Can't keep it above 12V. Buy a new battery, and take a ride. After 10 minutes or so, the miss returns in all its ugly glory. Sounds like both cylinders, but can't be sure. Miss gets worse. Stumble home and pull both plugs. Black, dry and very sooty -- See http://www.dansmc.com/Spark Plugs/Spark_Plugs_catalog.html (picture #3). Carbon fouled from running too rich? Question => Can an ignition system do that, too? Seems unlikely that both carbs have gone south at the same time? Unless "somebody" tried to rejet them after installing the HG Krome pipes? Ugh!! Question => Would the HG Krome pipes make an XV1100 run rich on stock jetting? Question => What could it cost to have somebody rejet my bike to the pipes? Check each plug for a spark outside the bike (grounded on the cooling fins), and notice a reasonably "blue" spark (considering that the battery has to drive the headlight, the starter and the CDI ignition). But both plugs are "firing" all over the place -- at the gap, between the insulator and the side wall and so forth. OK, so an overly rich mixture (or something?) is eating the plugs. Then I remember that this bike has a choke. I look up at the lever, hoping that I left the choke on. No such luck. Choke is off, and after thinking about it for a moment or two, decide that wouldn't cause all of my symptoms anyway. While I'm standing up, I open the tank and check the gas. Maybe a gallon or so left in there, and only 83 miles on the trip-o-meter. Let's see, 4.4 gallons minus the gallon or so left is 83 miles divided by 3.4 gallons works out to 22.4 gallons per mile?!! Should be more like 35-40, acording to you folks on this list. Beginning to look like carburetion? Install two new plugs (NGK NBR7ES at $3 each). Get up next morning, and ride. The miss comes back after about 10 minutes, and gets worse. Dies twice in traffic waiting for a green light. Restarts each time (new battery?) but runs like !@#$%... Limp home, and pull the new plugs. Black, dry and very sooty. Check both air cleaners, but they look clean, with no evidence of having been wet or anything like that. The shop where I bought it is a good 40 minutes from home. To heck with that, I think, so I order a tow truck. It's coming Monday. Until then, I am very open to all suggestions as to how to fix this problem or remove my head from my sit upon. Hey, whatever it takes![/color] [color="#000000"]p.s. my battery is good. Please oh please master motorbike guru god give me some divine intervention.... Muchos Gracius :) :) :)