Hello All,
I'm running out of ideas and hope that someone can help. At this point any idea on what to do next would really be appreciated. I have a 2001 Concours C10 with about 18,000 miles on it that I bought about a year ago. For the first 5000 miles the bike ran great, and got very consistent fuel economy (38-40 mpg). Then i decided that it was due for a valve adjustment. Honestly, i wasnt looking forward to doing it the first time, and the bike sat for about 3 months while i procrastinated. Then i finally got around to it, and the bike has run very poorly across the whole rev range ever since. Since the valve adjustment I've chased after anything I could think of and have done the following:
1) I had someone pull and clean the carbs, thinking that they were gunked up from my procrastination. They definitely had some gunk, but the bike did not run much better after the carb clean. It started much easier, and continues to start easily.
2). I've ridden only about 100 miles or so, because I'm really not sure if I'm doing damage to something because I don't know what's wrong. But in that time I've noticed that i get about 15mpg, and very reduced power. I can completely open the throttle on the highway in top gear and get to a max speed of 75 mph on level ground. I need to slip the clutch coming away from a stop sign or I'll stall. The idle is pretty rough, like what I'd expect to hear if 3 cylinders (or 2) were firing. Come to think of it, the power it's making is like only 2 or 3 cylinders are firing.
3) I rechecked the valves today. They were fine. I realized that I had reversed the polarity on the coils when i put stuff back together last time, though. For some reason on my bike the red wire leading to the coil is negative but i had assumed that it was positive. I put it back correctly this time (used a multimeter on the wires to ensure that I had it right) but it didn't make a difference. Still very low power and 15 mpg on the highway.
4) I changed the spark plugs. The old ones were very blackened (all 4, equally), which makes sense because the bike is definetly running very rich right now. I don't know why, it didn't when it was running well, but you can smell strong raw gas in the exhaust. The bike ran 5% better with new plugs, and still runs terribly.
5) My left exhaust can used to be shiny chrome. In the last 100 miles it was turned blueish. The right muffler still is shiny chrome. Any idea why one can turned and the other didn't? I feel strong and equal exhaust flow from both mufflers.
6) At the time of valve adjustment i also added an inline fuel filter. I don't think that this is a fuel starvation issue, though. The bike is running rich, and it runs terribly from the time that i start it. "Prime" for 15 seconds doesn't change anything. I'm assuming that if the fuel filter wasn't flowing enough fuel the bike would run fine for the first minute, and it wouldn't make the bike run rich.
7) I checked my air box and filter. Nothing out of the ordinary. No family of mice, gerbils, or deer have decided to move in and choke the air flow. Previous owner put in a K&N, but I don't think it's related to the problem because the bike was previously running great with it.
8) While the tank was off I tested for damage from hydrolock using the methods posted by Steve In Sunny Florida (Shoodaben Engineering) on YouTube. The pistons are right where they should be, no bent rods.
So, does anyone have any ideas on what to do next? I'm thinking that since all 4 spark plugs were black that helps narrow it down (it's not one bad coil or one carb that's resistant to cleaning). This is the only time that I was actually hoping to find a family of 12 mice in my airbox.... Thanks for any suggestions.
- Adam