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Discussion Starter #1
Lately my bike has been sluggish to start, and when it's a cold start, it always has to backfire once. Today it was about 2℃ (34℉) and it started, but I couldn't get any power. Eventually, it just quit altogether, and I flattened the battery trying to get it started again.
I'm inclined to think that it's lost compression, but how can I know? I don't have any gauges to measure it. I'm wondering if I should just call the repair shop and have them look at it.
 

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Sounds more like a weak battery and/or poor fuel mixture, to me. Batteries are weaker in the cold, and if your choke or enrichment circuit isn't up to it, you'll get the exhaust pop.
 

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Discussion Starter #5
Definitely not a battery problem. I was able to turn it over an awful lot when I first sat on it. But the mixture: why not? I'll have to look into how to tweak that.
 

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A battery can make the engine turn over, but not have enough voltage at the same time to make a good spark. Only way to tell is with a voltmeter, while cranking.
But, since you say it runs for a time on full choke, I guess balancing the choke may be the problem. When I start my CB450 in the cold, I have to pop the choke off as soon as it fires, and try to keep it running with the throttle, because full choke will kill it, and it won't idle when cold.
 

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It doesn't sound like compression.
However, that is a good reason to make friends with other bikers. To share tools and work on bikes.
I have all the compression tools, gauge, and fittings for m c sizes.
dc
 

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A battery can make the engine turn over, but not have enough voltage at the same time to make a good spark. Only way to tell is with a voltmeter, while cranking.
But, since you say it runs for a time on full choke, I guess balancing the choke may be the problem. When I start my CB450 in the cold, I have to pop the choke off as soon as it fires, and try to keep it running with the throttle, because full choke will kill it, and it won't idle when cold.
+1 a bad battery can still start the bike but will make it run poorly.
 

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compression test

if you really want a compression test that anyone can do is take the spark plug out and put your thmb over the hole and hit the starter button like you are going to start it ( i need a second person to do this) if your thumb is easily blown away from the hole you are prolly ok.
 
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