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Old 02-19-2013, 09:56 AM   #1
john479 OP
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Honda XL500R starting problem

Hi all,
I'm in need of a little advice on my XL500R restoration.

I can't get it to start or when it does, it only runs for 5 seconds. I've found that if I hold my manual decompression lever on and kick it over to prime it and then kick it, it sometimes does start but for only about 5 seconds. This makes it sound like a fuel problem but I've thoroughly cleaned the carb and used a good rebuild kit. It has a good spark and plenty of compression, so much that when trying a bump start, it locks the back wheel up. Tried a different CDI but exactly the same.

Anyone got any ideas?


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Old 02-19-2013, 11:56 AM   #2
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first off, is your gas tank venting?
Have you left the bowl off and are you sure you are getting good gas flow through the needle? If not could be petcock, carb, tank vent.
Do you have an intake leak (major) typically this would make it race but if it's a big leak it could lean it out a lot.
How old is the fuel?
Exhaust system is not plugged is it?
What year BTW. just the single carb, not that funky dual arrangement of the 600's is it?
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Old 02-19-2013, 12:52 PM   #3
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Might consider posting this in the Thumper section also.

Pull the spark plug, if wet then flooded. If dry and flaky, then going lean. Also check the stator to make sure it is still creating spark.

Set idle to round 2K RPM and adjust polit to 2.5 turns from full seat (IIRC) and then adjust from there.

Sometimes valve adjustments can make a big differance.

None of this will matter if you are trying to run old and/or dirty gas. There are lots of small holes and passages that old fuel can gum up both carb and pecock valve.

Hope this helps.
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Old 02-19-2013, 02:45 PM   #4
john479 OP
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Yes, I'm getting good flow throught the petcock and needle. Can't see I have an intake leak as I've changed the o-rings on the rubber boot and spacer and they''re done up tight. Exhaust is fine as I tried it without the exhaust and it did the same thing - ran for a few seconds if I prime it with full choke, holding decompression lever in. Then big kick and it will start but die after a few seconds. Does behave like fuel starvation.
It's 1982 so single carb thank goodness

I will try fresh gas although it's not that old and no signs of things getting gummed up. Even if the gas was old, surely it wouldn't run at all? Carb seemed ok when I rebuilt it. Probably didn't need new jets but since it came with the kit I changed them anyway. Main reason for the kit was new o rings and gaskets.

Thanks for the help
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Old 02-19-2013, 04:07 PM   #5
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Posted in Thumpers section also
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Old 02-19-2013, 04:42 PM   #6
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take the tank off and check the connections on the right side, I had one jiggle lose under there and gave me similar problems on my xl
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Old 02-19-2013, 08:33 PM   #7
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Does sound like a fuel problem. have you checked the petcock filter screen? Ive got a Mikuni on my Xl500 so I'm not familiar with the stock carb, but I've had to clean old carbs more than once before getting them to run.
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