Flapper valve mod.

Carried out this mod that a few guys have done on the UK forum. The noise control flap in the can is spring loaded. Under 3800rpm it stays shut, above a servo operated cable opens the valve. Some people have complained of a slight hesitancy at about this rev range. Now, i have removed the cable in it's entirety when i was having a look at the can, however, the quickest solution, and one that can be reversed easily, is to lift the seat off, remove the right side rear cowl (should be explained in your owners manual) and while the power is off, remove the end of the cable from the servo mech. This acts to allow the flap valve to stay open right from the off. The bike sounds more gruff at idle and seems smoother low down. I should add that i try to use the highest grade (98 ron) fuel i can find. A tank of cheap (ish) supermarket fuel today made the bike feel rough and tingly. One person has reported seeing an error code flash up after this mod, so be aware that it might cause issues - however 320 miles today and the bike is fine with the mod.

Speaking of, what's the manual say about fuel octane required?

There's a sticker on the tank that has a small 95 ron indicator and a large 98 ron indicator. Will run on either, but 98 is recommended.

Was the hesitation gone after this mod?

[image: View Post]paul thompson, on 21 June 2010 - 11:13 AM, said:

Carried out this mod that a few guys have done on the UK forum. The noise control flap in the can is spring loaded. Under 3800rpm it stays shut, above a servo operated cable opens the valve. Some people have complained of a slight hesitancy at about this rev range. Now, i have removed the cable in it's entirety when i was having a look at the can, however, the quickest solution, and one that can be reversed easily, is to lift the seat off, remove the right side rear cowl (should be explained in your owners manual) and while the power is off, remove the end of the cable from the servo mech. This acts to allow the flap valve to stay open right from the off. The bike sounds more gruff at idle and seems smoother low down. I should add that i try to use the highest grade (98 ron) fuel i can find. A tank of cheap (ish) supermarket fuel today made the bike feel rough and tingly. One person has reported seeing an error code flash up after this mod, so be aware that it might cause issues - however 320 miles today and the bike is fine with the mod.

[image: View Post]KPerham, on 21 June 2010 - 03:19 PM, said:

Speaking of, what's the manual say about fuel octane required?


In the US and Canada the number you would be looking for at the pump (PON Pump Octane Number) is 91 or higher

The bike feels smoother at low rpm. The hesitancy is still there - but only slight.

I had this done for a little while. The key to not having a code is to turn the servo to its normal position after you remove the cable.

Yes Premium gas is what the owners manual says and what it says on the warning sticker on the bike. I noticed a hesitation in 1st and 2nd gear as well that I attributed to this exaust flapper. It doesnt really bother me too much though. I dont think I will be modifing mine - not without an aftermarket system. In other words I will leave the oem can alone and just replace it when I get the money to do so, keep the oem as is.

I did this flapper mod today and I must say I like the sound of it. It's not a whole lot louder but it's clearly more visceral and audible at lower rpms. I don't think I'll be in the market for an aftermarket can, not only because they look so amature, but also I like the integrated look of the stocker and I've come to appreciate a nice sounding but muted volume. I guess I'm just getting old :biggrin:

[image: View Post]Solomoto, on 30 June 2010 - 12:35 AM, said:

I did this flapper mod today and I must say I like the sound of it. It's not a whole lot louder but it's clearly more visceral and audible at lower rpms. I don't think I'll be in the market for an aftermarket can, not only because they look so amature, but also I like the integrated look of the stocker and I've come to appreciate a nice sounding but muted volume. I guess I'm just getting old :biggrin:


TRY THIS: After disabling the flapper valve... Now remove the chrome cover that houses the 2 exhaust outlets - it is just 3 bolts. Then remove the cover that houses the flapper valve - 3 more bolts. Then replace the chrome cover. You will find that the sound is much better when not going through that funky looking cover with the triangle in the middle of it. And, if you don't like it just put it back.

I also just cut (dremel tool) the triangle out of the middle of the flapper cover. This sounds almost as good - but no triangle cover at all sounds best. Note that the purpose of the flapper cover may be to keep heat from coming into direct contact with the outer stainless steel cover which may discolor with heat - not certain. I am going to try it without the flapper cover for a while and see if I notice and discoloration on the chrome cover.

Overall look better from the back without that triangle cover (IMO).

[image: View Post]VFR12Pilot, on 05 July 2010 - 06:06 PM, said:

[image: View Post]Solomoto, on 30 June 2010 - 12:35 AM, said:

I did this flapper mod today and I must say I like the sound of it. It's not a whole lot louder but it's clearly more visceral and audible at lower rpms. I don't think I'll be in the market for an aftermarket can, not only because they look so amature, but also I like the integrated look of the stocker and I've come to appreciate a nice sounding but muted volume. I guess I'm just getting old :biggrin:


TRY THIS: After disabling the flapper valve... Now remove the chrome cover that houses the 2 exhaust outlets - it is just 3 bolts. Then remove the cover that houses the flapper valve - 3 more bolts. Then replace the chrome cover. You will find that the sound is much better when not going through that funky looking cover with the triangle in the middle of it. And, if you don't like it just put it back.

I also just cut (dremel tool) the triangle out of the middle of the flapper cover. This sounds almost as good - but no triangle cover at all sounds best. Note that the purpose of the flapper cover may be to keep heat from coming into direct contact with the outer stainless steel cover which may discolor with heat - not certain. I am going to try it without the flapper cover for a while and see if I notice and discoloration on the chrome cover.

Overall look better from the back without that triangle cover (IMO).


Ive done the flapper also, 200 miles and no CE light yet.

Sounds MUCH better at idle and @ low rpm. I will probably keep the stock can now. As non of the aftermarkets match the lines properly (cept the ones that dont allow u to use saddlebags)