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I've been playing around with my fuel and VE tables to try and get rid of a steady throttle hesitation at speed, and I think I've gotten it about as good as I can with my limited knowledge.

After each change I've taken the bike out and ridden normally for 100 miles or so to check the changes, and then once it cools off I've checked the plugs.

My rear plug is a nice even tan/light brown color, but the front is almost completely white. I've actually got the front cylinder running a bit richer than the rear, so I'm kind of confused as to why the plugs look the way they do. I thought whiter meant leaner. Is it normal, or at least okay, for one plug to be so different than the other?

Bike is running good at this point so I hate to change anything more in the map if I don't need to.
 

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For one thing the plugs burn whiter these days with todays unleaded gasoline. Especially on the cars.
I have noticed different readings from front to rear on both my bikes also..
I have a 71 Chevelle with Hot 454 and I noticed the plugs are burning lighter in color, and its not lean with a Huge holley..
 

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Snaps said:
I've been playing around with my fuel and VE tables to try and get rid of a steady throttle hesitation at speed, and I think I've gotten it about as good as I can with my limited knowledge.

After each change I've taken the bike out and ridden normally for 100 miles or so to check the changes, and then once it cools off I've checked the plugs.

My rear plug is a nice even tan/light brown color, but the front is almost completely white. I've actually got the front cylinder running a bit richer than the rear, so I'm kind of confused as to why the plugs look the way they do. I thought whiter meant leaner. Is it normal, or at least okay, for one plug to be so different than the other?

Bike is running good at this point so I hate to change anything more in the map if I don't need to.
The only "real" way to know is to AFR sniff each cylinder during different operational schemes.
 

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The front will always run leaner on a 45 degree V-Twin with a common intake manifold (plenum). If you were to draw up a intake event chart for each cylinder and then overlay them with a 45 degree offset you could see what is happening on every other intake cycle.

It would show the rear intake event just about to end as the front intake started to open. The flow into the rear cylinder at that point has built up considerable inertia (high velocity = low pressure) and doesn't want to change direction toward the high pressure area of the opening front port.

On modern bikes with so much cooling capacity this rarely shows it's ugly head, but back in the day of big iron head Sportsters running and setting world records (Warner Riley) at Bonneville on fuel this was a huge problem. Those big iron top Sportsters were converting energy at a rate that would produce five times the heat of a stock twin cam with less than a quarter of the Twin Cams cooling capacity and when the front went lean they would melt the front pistons.

The way around this was to mill a 4 degree angle on the intake manifold that would bias the flow by aiming the carb toward the front cylinder.

A 2 into 1 with a longer rear primary pipe goes a long way to alleviate this problem (dyno numbers). For reasons that are very hard to explain, the collector of the 2-1 pipe and the common intake plenum communicate sonically very well and in harmony with the common manifold V-Twin.

:cheers:
 
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