I got a good one. First, I have worked on Hondas for 43 years with my first being a Sport 50 C110.
I have a real problem issue right now with a 1970 trail 90. Background: The bike was rebuilt 1000 miles ago with bore and new piston, New valves and valve job, carb rebuilt, and clutch replaced. It has run great until reciently. I was riding it home the other day and on throttle, it slowed and felt like it was siezing. I thought maybe something might be in the carb abd leaning it out. Carb was spotless inside, fuel flow is excellent from the tank to the float bowl. I tried another test. I ran it up into 4th and when it started to slow, I shut off the gas and immediately stopped. I opened up the float bowl drain and waited until the fuel all drained out. It took 30 seconds or so, so I know that the carb is NOT starving for fuel. What is wierd is that the engine will bear down to almost a stall in fourth gear. I can push the shifter forward to disengage the clutch without letting off of the throttle. The engine won't pick up speed until I let off of the throttle and open it up again.
Well today I pulled the top end off expecting to find a gauled piston...No such luck! Piston looks good, valves look good, crank and rod feel
fine. Could this be an ignition issue? I was wondering if a condensor was bad or the charging system was somehow feeding the coil AC instead of DC. The engine doesn't miss, it just drags down. Any help MUCH appreciated!