View Full Version : Fatshots disc question

02-07-2010, 10:19 AM
I'm ordering some Fatshot slips for my 09 Street Glide and wondering if you use different number of discs on each side to compensate for difference in flow from each side ? In other words since there is less flow from left side do I use less discs to even things out ?

02-08-2010, 07:49 AM
On a bike equipped with the stock cross-over headpipe...A 2:1 ratio (right:left) is a good rule of thumb, beyond 6-8 discs as a babseline.

02-08-2010, 09:03 AM
Sounds like a pretty inexact science , would a guy just be better going supermeg to cut down on the "guesswork" . The whole process seems rather un precise anyway ? Thanks

02-08-2010, 11:28 AM
Wondering if an actual flow measurement has been taken on each side or are we just guessing with the number of discs on each side . Seems like it would be easy to actually hurt the performance of the bike with misadjusted back pressure . ?

02-08-2010, 01:54 PM
Take two bikes, same model, came off the assembly line right after the other. Put them through the same dyno pulls and you will most likely post different numbers. If you tear the machine down you'll find minor tolerance discrepencies/differences.
Throw in Geography (altitude) and nature (temp.) not to mention Minor/Major modifications and you can see the variables/combinations are endless.

We can provide suggestions or starting points for tuning from experience; however any combination can be tweaked and that is usually accomplished via experimentation and trial & error.

02-08-2010, 03:18 PM
I totally understand that but trial and error success can't really be accomplished by most without a dyno . Are you saying to install 6-8 fewer disc in the right side compared to the left . Again would the Supermeg eliminate this "guesswork " ? Thanks

02-09-2010, 07:09 AM
After installing 6-8 discs per muffler add 1 to the left for every 2 you install on the right.

02-09-2010, 08:41 AM
Fair enough , anxious to get them . Love to get the Supermeg but lots more $$$ . Thanks

02-09-2010, 11:15 AM
Correction to my answers involving you questions regarding the '09 touring model. The answers I gave are for '08 and earlier model stock cross over headpipes; however the '09-10's have a headpipe which comes together into a collector prior to seperating into duals. With that in mind '09-10 models run equal amount of discs both sides.

02-09-2010, 04:30 PM
Thanks , even though the 2010 is single muffler correct ?

02-10-2010, 07:19 AM
Some models have one...some models have two.