Low RPM backfire from one cylinder

jamesp said:
I understand your point, but there was way too much drama. Not sure what I did to make it better, but it’s much better now. Looking back, the tickler on the left carb would have fuel running out of it when used that was sometimes hard to stop. After adjusting the float a bit lower, that is not happening now that I have seen.
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Well! There's the rich causing the exhaust bangs! Should have mentioned that long ago! A flooding pilot circuit obviously will cause the 0-1/8 throttle to be wrong and will have little to no effect on larger throttle openings!
 
marshg246 said:
Well! There's the rich causing the exhaust bangs! Should have mentioned that long ago! A flooding pilot circuit obviously will cause the 0-1/8 throttle to be wrong and will have little to no effect on larger throttle openings!
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Now tis has got me thinking I want to recheck my float heights. I did perfprm a round of bowll flatting recently...could have altered float height enough I guess.
 
Tornado said:
Now tis has got me thinking I want to recheck my float heights. I did perfprm a round of bowll flatting recently...could have altered float height enough I guess.
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AMAL says: "Although the Concentric carburetter will function across a wide range of fuel levels, an accurate fuel level is the foundation of the overall jetting of the carburetter and makes a significant contribution to the smoothness and performance of an engine."

To me, fuel level and especially both carbs being the same is step one. Step two is slide sync. Without those, you cannot expect to have a properly running AMAL-equipped bike.
 
marshg246 said:
Well! There's the rich causing the exhaust bangs! Should have mentioned that long ago! A flooding pilot circuit obviously will cause the 0-1/8 throttle to be wrong and will have little to no effect on larger throttle openings!
Click to expand...
So is what you said a possible result of a float set too high?
 
jamesp said:
So is what you said a possible result of a float set too high?
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Yes, it's why I said more than once to check the float height (fuel height) and carb sync. Reread my posts #30 and #65.

It has been all over the place in this thread, but explosions in the exhaust (what you had) are unburned fuel for whatever reason. Multiple things can cause that but continual flooding at idle is sure to!
 
marshg246 said:
Yes, it's why I said more than once to check the float height (fuel height) and carb sync. Reread my posts #30 and #65.

It has been all over the place in this thread, but explosions in the exhaust (what you had) are unburned fuel for whatever reason. Multiple things can cause that but continual flooding at idle is sure to!
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Then I would suggest, that those who buy new carburetors, even from reputable sources, should go through them before installation to verify that what they are buying will live up to their expectations.
 
jamesp said:
Then I would suggest, that those who buy new carburetors, even from reputable sources, should go through them before installation to verify that what they are buying will live up to their expectations.
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Yes, of course you must setup the carbs. As far a fuel height, Premiers in the last 2-3 years are factory set and I've not found any wrong. These are the carbs with the test cable installed and the note about factory testing. Also, I'm happy to go through them but it's not right for me to mess with brand-new carbs before selling them unless asked.

You will find MANY on this site talking about the need to go through new carbs before installing. That was absolutely true before the Premiers and still true of the Premiers before AMAL started testing each one (have the test cable installed). AMAL added staff and a facility to do that testing as they were getting a bad name over adjustments and swarf.
 

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