Part Number: 441-729 in 09 JP Cycle Catalog page 219.
$34.99 sold in pairs.

"These high temperature steel cones have fully radiused edges for a greater imporvement in engine responsiveness, especially at low end torque. They offer correct back pressure for more horsepower".

I have never heard of these and just curious as to their function. Does anyone use these? Would they require a different map? Do they work? or just another BS wannabe or impractical modification?

Thanks and ride safe!

 

They are used to help create back pressure so you dont loose your bottom end torgue. I have them on my bike as i put the fullsac duals on mine.

 

I had em' in my samson short slashers, and they make your straight pipes sound more "tinny". Didn't like em', They are too restrictive for flow IMO.
You will get more from Thundermonster baffles from BCT, or at least I did.

 

jdreed520 how do you like the fulsac duals I have been looking at them
as they are not expensive

Leon

 

i don't recall the reference but it seems i remember that Twin Cam heads are designed to function like the cones therefore are not needed.

 

the fullsac duals are really good. I have been running them on my bike for about 2 years or so. Nice full sound and i don't feel any lack of low end torque...

 

Been used for years on drag pipes.

 

Save your money. They go in the wrong end of the pipe to do any good.....Think about it...Even HD sells thinner SE gaskets not to inhibit the flow of the exhaust outta the head. Power chasing guys look for ways to get the exhaust flowing and out of the head. The last thing they want to do is restrict the flow at the exhaust port....If you are looking for back pressure to increase bottom end, you would be better off with a bolt, lollipop baffle, or even shorty baffle in the other end of your pipe.

 

They stop the pulses that try and come back up the exhaust pipe and reenter the head, this pulse is very strong on pipes that are to big for a particular engine or drag pipes.
The old twin cams didn't need them because Harley had a big old step in the exhaust port that would have definatly slowed that pulse down, but the 96" Twin Cams don't have that step in the port anymore.
I have a set of heads that I had worked over for one of my Spotsters by Head Quarters and they send a set of those cones alone and want them used no matter what kind if exhaust you have, I would guess they are using them to excelerate the exhaust flow out of the combustion chamber and add to the scavenging effect.