Buccaneer
XS400 Enthusiast
Hi all,
My XS400SE ('US Custom', UK, 1981, 4G5, it is similar to the Specials) has starting problems as detailed in the carburetor thread. Oddly, once started it seems to run perfectly well. Gummed pilot circuit in the carbs is highly likely the major factor but I'm keen to check all the easier things /first/, then pull those complicated carbs apart for a thorough boiling at the weekend.
Valve clearances and points gaps have been checked and were all perfect. I recently did the static timing very carefully, one side was virtually perfect already and the other side was a few mm late of the mark. When this was put right it definitely made starting a bit easier.
1./ What is the acceptable range for ignition coil resistances? Mine measured PRI 3.6 Ohms and SEC 13.3k, exactly the same on both sides to 1 LSD of the meter. This was measured with a Fluke 75 according to the Haynes manual: Primary the Red / White bullets were pulled out of the loom and resistance measured to the orange cable. Secondary the caps were pulled off the plugs and resistance also measured from the caps to the orange cable. Haynes manual says it should be PRI 4 Ohms +/- 10% and SEC 9.5K +/-20%, so it seems a ways off but since both sides are the same my guess is the coil's OK?? Anyone else got figures from a 32 year old bike?! Should I rush out and buy new caps?
2./ Haynes says the symptom of condenser failing would be 'excessive
o) sparking at the points', not very helpful as it happened! By the time I was looking at this it was getting towards dusk, I could have ridden the bike safely at 30mph with the headlight off, but it might not have been legal, if that gives some clue to the light levels at the time... occasionally, say once every 2 to 10 seconds, I would see quite a big spark at one or other of the points, the rest of the time nothing or only very small sparks were visible. Has anyone any idea if this seems normal? I think I'm going to replace the twin condenser as a precaution anyway because it is fairly cheap and very easy, but interested in input on this to improve my knowledge.
I have access to a scope, presumably the waveform at the points would conclusively identify any condenser problems, if I knew what to look for... anyone know about that?
My XS400SE ('US Custom', UK, 1981, 4G5, it is similar to the Specials) has starting problems as detailed in the carburetor thread. Oddly, once started it seems to run perfectly well. Gummed pilot circuit in the carbs is highly likely the major factor but I'm keen to check all the easier things /first/, then pull those complicated carbs apart for a thorough boiling at the weekend.
Valve clearances and points gaps have been checked and were all perfect. I recently did the static timing very carefully, one side was virtually perfect already and the other side was a few mm late of the mark. When this was put right it definitely made starting a bit easier.
1./ What is the acceptable range for ignition coil resistances? Mine measured PRI 3.6 Ohms and SEC 13.3k, exactly the same on both sides to 1 LSD of the meter. This was measured with a Fluke 75 according to the Haynes manual: Primary the Red / White bullets were pulled out of the loom and resistance measured to the orange cable. Secondary the caps were pulled off the plugs and resistance also measured from the caps to the orange cable. Haynes manual says it should be PRI 4 Ohms +/- 10% and SEC 9.5K +/-20%, so it seems a ways off but since both sides are the same my guess is the coil's OK?? Anyone else got figures from a 32 year old bike?! Should I rush out and buy new caps?
2./ Haynes says the symptom of condenser failing would be 'excessive
o) sparking at the points', not very helpful as it happened! By the time I was looking at this it was getting towards dusk, I could have ridden the bike safely at 30mph with the headlight off, but it might not have been legal, if that gives some clue to the light levels at the time... occasionally, say once every 2 to 10 seconds, I would see quite a big spark at one or other of the points, the rest of the time nothing or only very small sparks were visible. Has anyone any idea if this seems normal? I think I'm going to replace the twin condenser as a precaution anyway because it is fairly cheap and very easy, but interested in input on this to improve my knowledge.I have access to a scope, presumably the waveform at the points would conclusively identify any condenser problems, if I knew what to look for... anyone know about that?
