View Full Version : End cap and disk equivelants and tunes

02-19-2008, 10:42 AM
I have a V5 2:1 on a 1250 V-rod. I ran it for a few months with 12 disks and the end cap in place. It ran well, there were spots in the RPM range that were way too rich in the tune. I later decided to run without an end cap and to get it dyno tuned. It runs well now.

I believe I was incorrectly informed by someone that 6 disks is the same as an open end cap. So I now have 6 disks and an open end cap, I figured the equivelant of 12 disks and the closed end cap. I think I have read now that the open end on the 5" is actually the same as 10-12 disks and a closed end cap. Should I drop down to 2 or so disks with the open end? Should I expect better performance if I did? Will this minor change require it to be retuned or is the effect of the disks with open end cap minor concerning AFRs?

Thanks in advance

02-19-2008, 03:59 PM
The 5" open end cap is equivelent to 10-12 discs. I'm a little confused at your comment regarding dynoing with out an end-cap. If that was the case and you dyno'd it without the endcap, it would be equal to flowing the core with no discs or end cap , = 24-26 discs + closed e-cap.

02-19-2008, 04:05 PM
Sorry I was confusing. I mean I had the PCIII tune done on a dyno with no end cap and 6 disks installed. Which I now see means it's the equivelant of 16-18 disks and the end cap on.

I was wondering if pulling 3 or 4 disks out now will require a retune or not.

thanks for the response.

02-20-2008, 07:15 AM
No, the bike should not need a retune. Removing 3-4 discs should get you close to your original flow. If you think your top end is starting to suffer, go back and add a disc or two.