Back fire when starting when warmed up

C

CaptCaper

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Joined
Dec 24, 2005
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39
Age
75
Location
Northern NH
Gives one loud backfire when starting. When it's warmed up. Not positive if it does it when cold starting yet as I just got it out of storage and got it going. Starts fast runs good except the one backfire when restarting. I put 91 no ethanol in it for storage.. not sure if that's doing it. Any clues were to start?
 
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CaptCaper said:
Gives one loud backfire when starting. When it's warmed up. Not positive if it does it when cold starting yet as I just got it out of storage and got it going. Starts fast runs good except the one backfire when restarting. I put 91 no ethanol in it for storage.. not sure if that's doing it. Any clues were to start?
Click to expand...

Check compression and make sure the carbs are clean.
 
MrSled said:
make sure the carbs are clean.
Click to expand...
When you do clean them, replace the seats. It sounds as if they leak when warm. Causing fuel to enter exhaust while still warm. Then the fuel detonates once started.
Misadjusted floats would more than likely leave a puddle on the floor overnight. But not necessarily.
 
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Thanks guys... seems to have vanished for now. It's been in storage for so long. Using it like crazy these last days with Grandson starting to ride. Even fresher fuel..some SeaFoam,etc.
What does this Valve show in the photo? On? or Off for heating the carbs. I had it the other way until this morning.. Seems to be On now heating the carbs?
 

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You are currently in the ON position witch will allow anti freeze to flow in series threw the mouth of each carb as to prevent them from iceing up.
 
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Clean the carbs pilots are dirty. Its a lean pop when its cold. Just let it idle until its warm on the heat ex-hangers by hand.
 
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Is the idle set up to high ? Years ago on the SRV's and SS 440's if the idle speed was up to high when you shut the motor off it would leave unburned gas in the exhaust manifold and pipe. When you went to start it the motor it would ignite that gas with aloud bang. Any chance of this happening ?
 
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