I recently bought an '03 VFR800 about a couple weeks ago. It's only got 10K miles on it, and has obviously been parked for most of it's life. The bike looks like it just rolled off the showroom, so I'm going to guess that previous owner kept it garaged. Since I picked it up, I changed/flushed the clutch fluid, changed the oil (it was originally overfilled), changed the thermostat (and consequently, flushed/changed the coolant), switched to 87/89 (whatever is cheapest at the pump), ran a fuel system cleaner additive through a tank, and changed the battery. As of right now, it runs ok at idle, it just smells like it's running rich, until it gets up to operating temperature (180 deg F). Once it gets warm, the smoke out the exhaust is very thick, and then the engine idle starts to slow down and eventually dies/stalls. When riding, I don't know if it stops, or if I'm just going too fast to let the smoke plume accumulate, but my gas mileage is horrible. I only made about 70 miles on almost an entire tank. Tire pressure was good. When I bought the bike, it had thick white smoke coming out of the exhaust, and there actually appeared to be fuel leaking from the cat. After 1 gas up with 87, the smoke had significantly reduced, for a time, but then later resurfaced. Tearing the bike down to the thermostat was enough of a headache for me, and I will continue repairs most likely through the local mechanic, but I want to have a good place to direct them towards instead of just throwing parts/money at the bike. I don't think it's the spark plugs, the engine sounds like all cylinders are firing. The service manual says either a pinched or clogged fuel hose, or a faulty pressure regulator. This doesn't entirely make sense to me, because if fuel flow was restricted, wouldn't that cause the bike to run lean, not rich? There's no smell of gas or sign of fuel leaks from the front of the bike. I feel there's some reason/something that is causing an excess (abundantly excess) amount of fuel to get dumped into the engine. Looking at Honda's breakdown on their computers, even the sensors shouldn't cause this much fuel to get dumped. Does anyone have any experience with this or at least a sound logical explanation on how this might make sense? I changed the thermostat on the whole engine running rich to warm up premise. The old thermostat was fine, and the problem persists, even with a new thermostat. I don't think it's the O2 sensors, and again, researching seems to show they would fail in a manner which would indicate the bike was running rich, and should get the computer to lean it out. I really think there's something mechanical going on... something that is bigger than what the sensors/computer can compensate for, I'm just not sure what. The mileage is so low, and the condition of the bike leads me to believe that most of the components are in good shape/in spec. It just a matter of figuring out which one isn't. Any help appreciated, but please provide some sort of explanation for your solution. Again, even if I end up going to a mechanic, I want to be able to pinpoint where they should focus their efforts to minimize the time the bike's in the shop, and how much they lighten my wallet. Thanks in advance! UPDATE: So I'm replacing the Fuel Pressure Regulator next, hopefully the parts get here before next weekend. If the issue persists after that, I'm probably going to just take the bike to the local mechanic and have them check/replace the fuel lines and filters and the vacuum lines, or whatever other further troubleshooting required to sort this thing out. I'm feeling pretty good about the FPR being the culprit, but I felt the same way about the thermostat too... Will update with results. UPDATE #2: The FPR was the issue. The old one had fuel in the air vacuum line side, and installing a new one immediately resolved all of the listed symptoms. The bike smoked a lot at first, probably clearing out residual fuel in the exhaust system, but after a warm-up and a good test ride, the smoke was gone, and did not return.