Join Date: Mar 2009
Location: near Charlottesville, VA
Drops out at 4,000 rpms
First time poster, but I've been spying for a while. Lots of great info. I bought a 99 vn750 a couple months back. Immediately ran a couple tanks of Seafoam. No real problems, except the decel popping. Did the coaster mod. It helped a little, not much. Last week I took a ride and at about mile 50 the bike starting acting like it was out of gas. Had to pull off the road. Opened the fuel tank and there was no "swish". Tried to start it back up and bingo. Everything was fine the rest of the ride. Two days later I went out to start it up and it's been messing up since. Starts fine, idles fine, but when you get up to around 3500 to 4000 rpms, in any gear, you start losing power like your starving for fuel.
So I pulled the fuel stem: its clear and clean. No vacuum on the tank. But I drilled out the holes in the cap just in case. I pulled and cleaned the carbs, but everything seemed clean, no rust, no gunk, no debris. Put the carbs back on, sync'd, etc. and still have the problem, and have more popping now. If I keep it under 3000 rpms it runs great. But if you push it, it just starts to jerk and hesitate.
The plugs are almost new and no fouling. The float level of the rear carb is square on, the level on the front is about 1/8in low. Is that enough to matter?
Petcock inspected. All the parts look fine. I'm stumped at this point and pissed, 'cause its above 70 this weekend and my bike is sick. I'm looking for ideas if anybody has time. Thanks.