My 81 CB650 is on the fritz, stumping the best wrenchers I've met. I solved a number of probs recently, but keep making more it seems. She is still down for the count. Here are the probs, starting with the strangest...
- In 1st gear, I'll get a loud decompression hiss sound once or twice. Sounds very bad. Haven't met anyone yet whose even familiar with this. This is not the continuous engine hiss. This is a loud 1 second long air leakout noise.
- In 1st gear, bike drops dead zones erratically. Very jerky stuttering acceleration. Higher gears seem to cruise until I shift down and try to idle.
- In idle and 1st gear, requires a little throttle at all times or will stall out.
- Requires full choke to start for one second, dies, then requires closing choke to successfully turn-over. Will not run at all with choke out. Idles erratic, idle screw in makes it go wild, idle screw out makes it stall out. Finding good idle is possible but not for terribly long or consistently, especially when hot.
I've tested compression. All 4 good. Replaced an ignition coil and both ok. Replaced CDIs / igniters. Cleaned carbs, even the pressed slow jets. Dynamically synced. Plugs dark, dry, and sooty. :/ 4 hot cylinders. 80% avg battery power. Set pilot/mixture screws to factory setting; 2 1/4 from seated. Cannot get a great idle to get out of factory setting.
I cannot live without her.
Please help. Anything will help and teach this newbie a thing or two. Thanks!!! - Andrew
- In 1st gear, I'll get a loud decompression hiss sound once or twice. Sounds very bad. Haven't met anyone yet whose even familiar with this. This is not the continuous engine hiss. This is a loud 1 second long air leakout noise.
- In 1st gear, bike drops dead zones erratically. Very jerky stuttering acceleration. Higher gears seem to cruise until I shift down and try to idle.
- In idle and 1st gear, requires a little throttle at all times or will stall out.
- Requires full choke to start for one second, dies, then requires closing choke to successfully turn-over. Will not run at all with choke out. Idles erratic, idle screw in makes it go wild, idle screw out makes it stall out. Finding good idle is possible but not for terribly long or consistently, especially when hot.
I've tested compression. All 4 good. Replaced an ignition coil and both ok. Replaced CDIs / igniters. Cleaned carbs, even the pressed slow jets. Dynamically synced. Plugs dark, dry, and sooty. :/ 4 hot cylinders. 80% avg battery power. Set pilot/mixture screws to factory setting; 2 1/4 from seated. Cannot get a great idle to get out of factory setting.
I cannot live without her.
Please help. Anything will help and teach this newbie a thing or two. Thanks!!! - Andrew