i realize more with my new sprocket but i get to 8500 quick and it seems thats where my fuel cut is.  i feel like the engine pulls hard up to this point and it seems abnormally low.  My buddy's bike is a 620 and revs to 10500 without issue.  I realize its a smaller engine and revs physics says it should rev more freely but i feel like 8500 is low for redline for my bike.  is this normal?  i thought i remember seeing someone say their redline was higher on an S4.  can i safely raise fuel cut (power commander perhaps)?

i dont think that 10500 is correct. the reve limiter on the 620 should be is right around 8700 rpm. thats what mine was, with a 14t sprocket. same is true for my s2r1000.
regardless, there is no reason to go way up there, as you have passed peak power long ago.

not sure on your s4, but i would guess it is a little higher than 8700 when stock.
these bikes dont have the same huge high end revs that UJM's have.

4vs should still be making power at 8000rpm. Whats the redline on those 916s?
2vs are done at 8,000rpm and rev limit is very close to that. It shouldnt even be able to rev up to 10500.

Quote from: He Man on October 08, 2008, 09:35:47 AM
4vs should still be making power at 8000rpm. Whats the redline on those 916s?
2vs are done at 8,000rpm and rev limit is very close to that. It shouldnt even be able to rev up to 10500.

hmm...as far as teh 620 goes, i test rode the bike for him and noticed it revving like that so i'm not really sure whats going on.  I pretty sure i saw the tach spining over the 9-10k range.  i'll ride it again this weekend and double check though.

i would think my bike would spin higher than 8500 ish rpm since its a sbk sourced engine but could be wrong. i'll wait for more input from folks, hopefully someone knows whats going on.

Surprising enough, your S4 has a low red line for a 4 valver, 9K RPM.  Before doing anything, check your tach against a good handheld tachometer. 

The rev limiter on my S4 cuts in sharply at 9,500.
The owner's manual says to not go over 9,000.

620 owner's manual says to not go over 10,000.
Brad Black's Moto-One test report shows a 620 hitting the limiter at 10,500.

Subject to tach accuracy, as Howie said.

Quote from: Speeddog on October 08, 2008, 10:16:42 AM
The rev limiter on my S4 cuts in sharply at 9,500.
The owner's manual says to not go over 9,000.

620 owner's manual says to not go over 10,000.
Brad Black's Moto-One test report shows a 620 hitting the limiter at 10,500.

Subject to tach accuracy, as Howie said.

sweet, thats the info i was looking for.  is there any way to safely bump up the rev limit on my S4?  I'd love to get it to spin a little faster

Ducati Performance ECU or FIM/Ultimap U59 ECU are the only ways you'll bump the redline.

DP ECU bumps it to 10,500, I think.
FIM/Ultimap U59 ECU is adjustable, you can set it to whatever you want.

Neither are cheap.