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14 Posts
1983 Shadow 500
Bike starts fine when cold, but after warming up gradually loses low-end power to the point I have to baby the clutch and throttle much more than normal in first from a dead stop. Eventually, it will start cutting out in overdrive if I ride it long enough. If I do several short runs, it starts cutting out even quicker. When hot, it is a bit stubborn to start.
At first I thought it was overheating. I can't tell by the gauge, since it doesn't work. But the fan doesn't seem to be running more than normal, coolant isn't boiling out and there's no coolant in the oil. Then I thought it was the carbs, possibly the enrichment circuit or low speed jets, but that really wouldn't be temperature related that I could see.
Finally I decided to test the ignition system. The coils tested fine, 2.6 resistance on both which is a sign they're getting old from what I've read here and on other sites. All other ignition tests passed within specs listed in the manual. Since it only acted up when hot, I took it for a fairly long run. By the time I got back, it had reached the sputtering stage, so before it could cool down I tested the primary resistance. This time the front coil tested 9.5 ohms and the rear tested 8.2.
This seems to tell me that the coils are bad, cutting out after heating up, but since there is no mention anywhere I can find of the coil resistance being different after heating up I wanted to make sure before I handed over the money for new coils. On a side note, sometimes when it's hard to start hot I smell gas, like I've flooded it a bit. I just figured that was unburned gas from the spark not being hot enough.
So are my coils definitely bad or are there other tests I need to do before I spend the money?
Bike starts fine when cold, but after warming up gradually loses low-end power to the point I have to baby the clutch and throttle much more than normal in first from a dead stop. Eventually, it will start cutting out in overdrive if I ride it long enough. If I do several short runs, it starts cutting out even quicker. When hot, it is a bit stubborn to start.
At first I thought it was overheating. I can't tell by the gauge, since it doesn't work. But the fan doesn't seem to be running more than normal, coolant isn't boiling out and there's no coolant in the oil. Then I thought it was the carbs, possibly the enrichment circuit or low speed jets, but that really wouldn't be temperature related that I could see.
Finally I decided to test the ignition system. The coils tested fine, 2.6 resistance on both which is a sign they're getting old from what I've read here and on other sites. All other ignition tests passed within specs listed in the manual. Since it only acted up when hot, I took it for a fairly long run. By the time I got back, it had reached the sputtering stage, so before it could cool down I tested the primary resistance. This time the front coil tested 9.5 ohms and the rear tested 8.2.
This seems to tell me that the coils are bad, cutting out after heating up, but since there is no mention anywhere I can find of the coil resistance being different after heating up I wanted to make sure before I handed over the money for new coils. On a side note, sometimes when it's hard to start hot I smell gas, like I've flooded it a bit. I just figured that was unburned gas from the spark not being hot enough.
So are my coils definitely bad or are there other tests I need to do before I spend the money?