Finished a boat-load of work on my bike completing essentially all I want to do as far as custom work goes ... just need to paint everything. I would post pics but I keep getting some stupid error message saying something about a security token ... whatever that means. Last night and this morning it ran like a Swiss time piece ... this afternoon it ran like a piece of ... something else. Kept backfiring intermittently... I've been through the carbs twice, re-jetted them the day before yesterday since I put glasspacks and UNI pod filters on but it's running precisely the same as it ran back in April/May when I put it down for renovations. It'll start up just fine but if I let go of the throttle for more than 2-3 seconds, it's dead. It'll hiccup like a backfire and sputter down and die. I went through the timing back in April and set it to perfection. I balanced carbs back then and found a vacuum leak which made significant improvements but it still backfired then and now. Only thing I haven't done is valve adjustment as I figure that if valves were the problem, it would backfire every single revolution, not intermittently. I ride along Lake Shore Drive on my commute ... it's getting increasingly tempting to send it to the bottom of the lake. I've had three Harleys (one was 1/2 owned), two 1980's Hondas (4 cyl), and this Yamaha. I've rebuilt carburetors on all of these machines and never once had a single issue ... until this XS400. Any advice would be appreciated. Thank you for taking time to read this.
- J