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04-01-2021, 08:13 AM | #1 |
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Location: 36 miles north of Albany NY
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Backfire all the way home
I drove my ‘41 from the storage unit to home about 4 miles, once warmed up it backfired all the rest of the way. It also backfires while it idles. I had Skip rebuild the coil and Charlie NY do the carb two years ago, Tubman condenser, helmet has not been touched. Previous owner put new plug wires. I suspect a valve hanging up as the Reds headers have the paint burning off the driver side but not the passenger side. I have a vacuum gauge and a pressure gauge to check fuel. It has an electric pump and mechanical pump.
As soon as it stops snowing I’ll get it out into the driveway to trouble shoot). Is there a checklist of where to start? |
04-01-2021, 08:50 AM | #2 |
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Re: Backfire all the way home
Faulty condensor if I was a betting man.
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04-01-2021, 09:04 AM | #3 |
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Re: Backfire all the way home
>>>I suspect a valve hanging up as the Reds headers have the paint burning off the driver side but not the passenger side.>>>
Do you mean a backfire sound or pop from raw gas igniting in the exhaust system, not back up thru the carb? Jack E/NJ |
04-01-2021, 09:47 AM | #4 |
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Re: Backfire all the way home
Sounds like thru exhaust.
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04-01-2021, 09:59 AM | #5 |
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Re: Backfire all the way home
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04-01-2021, 10:33 AM | #6 |
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Re: Backfire all the way home
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04-01-2021, 10:59 AM | #7 |
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Re: Backfire all the way home
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04-01-2021, 07:15 PM | #8 |
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Re: Backfire all the way home
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04-01-2021, 08:08 PM | #9 |
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Re: Backfire all the way home
Run a QT of MMO or AT fluid thru it before you try anything. KISS
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04-01-2021, 08:23 PM | #10 |
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Re: Backfire all the way home
A back fire is where the fire comes back through the intake plenum and carburetor. An after fire is where fuel gets past an exhaust valve and ignites in the exhaust with a loud report. A sticky valve or more is generally the cause. Engines don't like to set for too long. MMO down the carb with some in the fuel might do the trick.
Back fire is generally caused by a lean condition in the carburetor. Occasionally a carbon tracked or cracked distributor cap can cause a cross fire to the wrong cylinder at the wrong time. A bad condenser generally causes a miss fire of one or more cylinders with poor or no idle. |
04-02-2021, 02:12 PM | #11 |
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Re: Backfire all the way home
Clean and check points for gap. Run Carb Cleaner through carb also.
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04-03-2021, 01:18 PM | #12 |
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Re: Backfire all the way home
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04-03-2021, 01:25 PM | #13 |
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Location: 36 miles north of Albany NY
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Re: Backfire all the way home
Here’s what my plugs look like.
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04-03-2021, 02:23 PM | #14 |
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Re: Backfire all the way home
Mixture rich. Clean plugs and it'll prolly run fine again. Jack E/NJ
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04-03-2021, 05:38 PM | #15 |
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Re: Backfire all the way home
Basic mechanicals seem adequate. Missing is likely ignition related problem. Plugs are indicating miss firing or over rich condition.
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04-03-2021, 06:29 PM | #16 |
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Re: Backfire all the way home
__________________
The only thing nice about being imperfect is the joy it brings to others.... "Silver rings, your butt! Them's washers!" "We shot our way out of that town for a dollar's worth of steel holes!" - from 'The Wild Bunch' - 1969 https://www.youtube.com/watch?v=7NReUd2_0u0 |
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