RPC3
XS650 Addict
Hi Guys,
Fall season wrapped up with a little riding, most of my time was focused on my wedding and some other house projects. Bike is put away for the winter in my shed, but accessible to be worked on, which I'd like to do.
When I last worked on my bike it was to fix some carb issues I was having, and they were never really solved. Through some trouble shooting on the forum it was determined that my throttle shaft seals were bad. I replaced them with OEM seals, but my bike still seems to have fuel issues AFTER the bike is warmed up and has been ridden for 10-20 minutes.
A short recap on my fuel system/updates:
1978 standard, bs38 carbs, stock tuning with aftermarket mufflers (installed by prior owner, similar to stock but a hair shorter), main jets are 145s, idle jets are stock. New fuel lines, fuel filters in place. I've set cam chain tension, valve height, timing per manual (95% this is all set). Carbs were completely rebuilt and gone through TWICE, with compressed air and new gaskets/seals, including the throttle shaft seals. New springs on the mechanical advancers, advance rod freshly greased, advance timing happens within acceptable spec. Bike is completely re-wired with a new harness, new battery, new regulator/rectifier. Only old components left in my ignition are the stock coils, stock condensers, and stock points. Carbs were bench synced, then balanced with a homemade manometer, I did not have issues balancing them. Charging system is perfect (brushes, rotor, battery - all working great).
I fully understand that there is a CHANCE I've done some of my maintenance incorrectly, but I did it very by the book, researched the forum extensively, asked and received help multiple times, and believe I followed the correct order of operations.
So back to my current issue - the bike will idle cold perfectly well at 1,100-1,200 rpm, it does not backfire, it does not hiccup or have any flat spots when riding for the first 10 minutes. After the bike is warmed up the idle will start to climb a bit (wants to sit around 1,400-1,600 rpm), it will occasionally die when I come to a stop in first gear and pull in the clutch, and ONCE WARM it appears to still have an air leak by my throttle shaft seals. The bike is low miles (12,000) and a New England bike, so it seems like a worn out bore where the shaft seals sit would be unlikely, but I'm sure it isn't impossible. Aside from idle, even when warm, the bike seems to drive perfectly fine - though it has felt "faster" in the past, meaning I think my performance is probably suffering due to either the air leak or inadequate combustion. I will *rarely* get some popping on decel, but it is not the norm.
Quick side note - I did make the mistake of getting into a discussion about this with a non-xs650 person, he was convinced my diaphragms looked shot (they seal and they don't have any tears - but I think he was saying the rubber didn't look as pliable as he's used to seeing. I haven't seen many posts addressing diaphragms as being a common issue from being "tired", so I'm not sure if his claim is legit or related to my problem).
My question is - what would you attack next? I really wanted to put in a pamco in with an optical advancer, but I don't want to ignore the carb problem. I'm sure the pamco would help (along with the new coils, lack of condensers, lack of points, and perfect advancing), but it'll be easier to tackle the carb issues first. I'm expecting to hear people say my carbs are shot, or probably that I've done something incorrectly (I'm not claiming to be an expert mechanic, but I can follow instructions as good as anyone and I go slow and careful). Since we've already gotten snow a few times this year I don't think my next drive will be until early May, but I'd like to get some of the work done over the winter months. If this was your bike, what would you do next?
Fall season wrapped up with a little riding, most of my time was focused on my wedding and some other house projects. Bike is put away for the winter in my shed, but accessible to be worked on, which I'd like to do.
When I last worked on my bike it was to fix some carb issues I was having, and they were never really solved. Through some trouble shooting on the forum it was determined that my throttle shaft seals were bad. I replaced them with OEM seals, but my bike still seems to have fuel issues AFTER the bike is warmed up and has been ridden for 10-20 minutes.
A short recap on my fuel system/updates:
1978 standard, bs38 carbs, stock tuning with aftermarket mufflers (installed by prior owner, similar to stock but a hair shorter), main jets are 145s, idle jets are stock. New fuel lines, fuel filters in place. I've set cam chain tension, valve height, timing per manual (95% this is all set). Carbs were completely rebuilt and gone through TWICE, with compressed air and new gaskets/seals, including the throttle shaft seals. New springs on the mechanical advancers, advance rod freshly greased, advance timing happens within acceptable spec. Bike is completely re-wired with a new harness, new battery, new regulator/rectifier. Only old components left in my ignition are the stock coils, stock condensers, and stock points. Carbs were bench synced, then balanced with a homemade manometer, I did not have issues balancing them. Charging system is perfect (brushes, rotor, battery - all working great).
I fully understand that there is a CHANCE I've done some of my maintenance incorrectly, but I did it very by the book, researched the forum extensively, asked and received help multiple times, and believe I followed the correct order of operations.
So back to my current issue - the bike will idle cold perfectly well at 1,100-1,200 rpm, it does not backfire, it does not hiccup or have any flat spots when riding for the first 10 minutes. After the bike is warmed up the idle will start to climb a bit (wants to sit around 1,400-1,600 rpm), it will occasionally die when I come to a stop in first gear and pull in the clutch, and ONCE WARM it appears to still have an air leak by my throttle shaft seals. The bike is low miles (12,000) and a New England bike, so it seems like a worn out bore where the shaft seals sit would be unlikely, but I'm sure it isn't impossible. Aside from idle, even when warm, the bike seems to drive perfectly fine - though it has felt "faster" in the past, meaning I think my performance is probably suffering due to either the air leak or inadequate combustion. I will *rarely* get some popping on decel, but it is not the norm.
Quick side note - I did make the mistake of getting into a discussion about this with a non-xs650 person, he was convinced my diaphragms looked shot (they seal and they don't have any tears - but I think he was saying the rubber didn't look as pliable as he's used to seeing. I haven't seen many posts addressing diaphragms as being a common issue from being "tired", so I'm not sure if his claim is legit or related to my problem).
My question is - what would you attack next? I really wanted to put in a pamco in with an optical advancer, but I don't want to ignore the carb problem. I'm sure the pamco would help (along with the new coils, lack of condensers, lack of points, and perfect advancing), but it'll be easier to tackle the carb issues first. I'm expecting to hear people say my carbs are shot, or probably that I've done something incorrectly (I'm not claiming to be an expert mechanic, but I can follow instructions as good as anyone and I go slow and careful). Since we've already gotten snow a few times this year I don't think my next drive will be until early May, but I'd like to get some of the work done over the winter months. If this was your bike, what would you do next?