I have a 2001 Road King Classic and just did the 98" big bore. With the big bore I installed a PCIII, had the heads done, and the throttle body bored and had it dynoed. I was surprised at the dyno results, 89.7 HP, 103.1 torq., 14.7 AFR., thought the HP and torque were a little low and the AFR high. The shop that did the dyno told me the only way to get more was to go with a better exhaust. I kept the stock headers and have V&H classic slip-on mufflers. They suggest a 2 into 1 exhaust but I like the two pipe look. Is there any other options?

 

For sure lose the stock headers and go with a dual, or 2 into 1 system. For duals, Hard Krome (below), no clamps or slip-ons, fantastic performance, sound and looks. Favorite 2 into 1 would be, Bassani Road Rage. Your AFR looks lean compared to most!

 

Thanks for the feed back. The dyno shop said to stay away from true duals cause it hurts torque. The shop I bought the kit from said the AFR should be about 13.25. How's that sound to you?

 

You won't lose much with duals, if any, unless it's a drag bike or ya ride WFO all the time. 13.25 looks about normal.

 

14.7 is waaaaay lean

Any dyno number can be subjective. Run you rear tire pressure up to 50 and see what happens to your dyno numbers
Even the operator can be late on the throttle and give funny numbers. Was the bike in 4th gear during the pulls

 

I thought the higher the number, the richer it is? No? Correct me if I'm wrong!

Thanks!

 

That's what I thought too. I thought 14.7 meant I was running too rich. Man this stuff can be confusing.

 

Stable combustion conditions require the right amounts of fuel and oxygen. The combustion products are heat energy, carbon dioxide, water vapor, nitrogen, and other gases (excluding oxygen). In theory there is a specific amount of oxygen needed to completely burn a given amount of fuel. In practice, burning conditions are never ideal.

When air and gasoline are mixed together and ignited, the chemical reaction requires a certain amount of air to completely burn all of the fuel. The exact amount is 14.7 lbs of air for every pound of fuel. This is called the "Stoichiometric" Air/Fuel ratio. It's also referred to the Greek letter "lambda."

When lambda equals one, you have a 14.7:1 Stoichiometric Air/Fuel ratio and ideal combustion. When the Air/Fuel ratio is greater than 14.7:1, lambda also will be greater than one and the engine will have a lean mixture.

Lean mixtures improve fuel economy but also cause a sharp rise in oxides of nitrogen (NOX). If the mixture goes too lean, it may not ignite at all causing "lean misfire" and a huge increase in unburned hydrocarbon (HC) emissions. This can cause rough idle, hard starting and stalling, and may even damage the catalytic converter. Lean mixtures also increase the risk of spark knock (detonation) when the engine is under load.

When the Air/Fuel ratio is less than 14.7:1, lambda also is less than one and the engine has a rich fuel mixture. A rich fuel mixture is necessary when a cold engine is first started, and additional fuel is needed when the engine is under load. But rich mixtures cause a sharp increase in carbon monoxide (CO) emissions. When the relative proportions of air and fuel are "just right," the mixture burns clearly and produces the fewest emissions. The trick is balancing the mixture as driving conditions, temperatures and loads are constantly changing.

 

RINEHARTS!

 

14.7 means 14.7 parts air to 1 part fuel. To make the mix richer, the number of parts of air have to be decreased. So 13.2 to 1 would be richer than 14.7 to 1.

Hope this clears it up a little for you.