Hi guys,
Thanks in advance for any help you offer, reading through many of the posts has already been very informative. I am new to riding motorcycles and also a new xs650 owner. I have a '79 special that is all stock except for a new Commando Exhaust system from Mikesxs (bike came without exhaust). A friend did me a big favor and cleaned the carbs for me as well as got it to the point that I could ride it. The jets were stock sizes (27.5 pilot, 135 main) but in order to get the bike to pull through the full throttle range, the needle clip had to be moved to the richest setting. This has allowed me to ride the bike, pass license tests, etc. The more I ride it though, the more I suspect the original lean condition isn't fully remedied. I also recognize that it is not ideal to be n either the richest or leanest needle setting. I will start with what I think are symptoms, feel free to say otherwise.
- Idling - bike starts right up with choke and when I take choke off I have to give it a little throttle to keep it running until the bike gets hot. (Though I figured this is pretty normal) After the motor is hot, if I leave it idling, it does ok for about 30 seconds but then after that the rpms start to drop and it will stall unless I give it gas. If I adjust the idle speed screw/throttle stop to where it stays running, once hot, each time I pull the clutch or come to a stop the rpms stay high at about 3000 rpm unless I turn the idle speed way down. So I basically can't idle without either giving it just a little gas or having it float at high revs.
-Riding - when I first take off, there is a hesitation right off idle after which the bike jerks into motion, but then I can go through the rest of the gears no problem. Once in a while it can feel a little jerky at the ~1/4 throttle range. Also, when riding with a passenger this starvation/jerky behavior happens when just going along.
-I am assuming this all means lean running. Both in other posts I have read here as well as in the Commando Exhaust paperwork, it has been recommended to go 140-145 in the mains and potentially one size up in the pilot jet. (From 27.5 to 30 I assume) In other posts I have read here they say go up one size in the mains per mod, which would move my stock mains to a 137.5, not the 2-4 size jump that is recommended in the Commando literature. I am planning on ordering the 30 pilot jets. My question is about the discrepancy about which mains. If I go for 1-2 sizes up I would order 137.5 and 140 mains, but if I follow recommendations from Mikes, order 140 and 142.5. Does anyone here have experience with this exhaust system or have a recommendation on which range of main jets to order? I would prefer to only order 2 sizes that are most likely to work and narrow to 1. Please let me know what you think as well as if I am on the right track in thinking that my bike is running lean.
Thanks,
-Dustin
Thanks in advance for any help you offer, reading through many of the posts has already been very informative. I am new to riding motorcycles and also a new xs650 owner. I have a '79 special that is all stock except for a new Commando Exhaust system from Mikesxs (bike came without exhaust). A friend did me a big favor and cleaned the carbs for me as well as got it to the point that I could ride it. The jets were stock sizes (27.5 pilot, 135 main) but in order to get the bike to pull through the full throttle range, the needle clip had to be moved to the richest setting. This has allowed me to ride the bike, pass license tests, etc. The more I ride it though, the more I suspect the original lean condition isn't fully remedied. I also recognize that it is not ideal to be n either the richest or leanest needle setting. I will start with what I think are symptoms, feel free to say otherwise.
- Idling - bike starts right up with choke and when I take choke off I have to give it a little throttle to keep it running until the bike gets hot. (Though I figured this is pretty normal) After the motor is hot, if I leave it idling, it does ok for about 30 seconds but then after that the rpms start to drop and it will stall unless I give it gas. If I adjust the idle speed screw/throttle stop to where it stays running, once hot, each time I pull the clutch or come to a stop the rpms stay high at about 3000 rpm unless I turn the idle speed way down. So I basically can't idle without either giving it just a little gas or having it float at high revs.
-Riding - when I first take off, there is a hesitation right off idle after which the bike jerks into motion, but then I can go through the rest of the gears no problem. Once in a while it can feel a little jerky at the ~1/4 throttle range. Also, when riding with a passenger this starvation/jerky behavior happens when just going along.
-I am assuming this all means lean running. Both in other posts I have read here as well as in the Commando Exhaust paperwork, it has been recommended to go 140-145 in the mains and potentially one size up in the pilot jet. (From 27.5 to 30 I assume) In other posts I have read here they say go up one size in the mains per mod, which would move my stock mains to a 137.5, not the 2-4 size jump that is recommended in the Commando literature. I am planning on ordering the 30 pilot jets. My question is about the discrepancy about which mains. If I go for 1-2 sizes up I would order 137.5 and 140 mains, but if I follow recommendations from Mikes, order 140 and 142.5. Does anyone here have experience with this exhaust system or have a recommendation on which range of main jets to order? I would prefer to only order 2 sizes that are most likely to work and narrow to 1. Please let me know what you think as well as if I am on the right track in thinking that my bike is running lean.
Thanks,
-Dustin