Flapper Valve disconnect on 2013 equals no starting from hot rest

Jul 2014
18
0
Crab Country
So for a week I had played with the exhaust flapper valve disconnected under the seat (wires harness only.)

I liked the way it ran, and it appears to be smoother in the low revs.. But during our heat wave this week 102F.. I started the bike from a days rest and it kept stalling gout as the RPMS dropped below 1000.. I plugged the harness back in and no issues.. So I assume this flapper controlling back pressure actually does something other than control sound at low revs.. Not knowing to much about engine combustion i can only assume the flapper closing as the revs drop maintain back pressure which keeps the engine happy..

I did notice the last time I had it unplugged I pulled over in the rain.. turned the bike off waited 10 minutes and she didn't want to start.. Plugged back in and no issues..

Anyone else experience this? I am happy I didnt pull the exhaust and remove the flapper permanently.. I would have hated to have this problem then and have no solution for it
 

RSL

May 2015
913
1
Dallas, Texas
Doesn't the added back pressure tune the exhaust for better performance?
 
Jul 2014
18
0
Crab Country
I don't know, but I do know lots of guys deactivate it or remove it completely..

But I would assume it's there for a purpose other than to make it sound quieter at low revs

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Mar 2013
2,334
4
Naples, IT
The only trend of stalling was related to an early ECU update. My flapper has been disconnected for 10K miles and never had that issue, and most of that was in SE USA, with summer air temps in the 90's-100's.

I will say a disconnected flapper normally is performed with some kind of flow performance upgrade: can, intake, tuner, etc.
 
Jul 2014
18
0
Crab Country
The only trend of stalling was related to an early ECU update. My flapper has been disconnected for 10K miles and never had that issue, and most of that was in SE USA, with summer air temps in the 90's-100's.

I will say a disconnected flapper normally is performed with some kind of flow performance upgrade: can, intake, tuner, etc.
My bike is bone stock other than farckles.. it's a 2013 recently completed all recalls (throttle and cam bus)..

so are you saying that if I want to take advantage of disconnecting the flapper I would need to rune it or do some other mods like exhaust and or air box?

Sent from my Pixel 2 using Tapatalk
 
Mar 2013
2,334
4
Naples, IT
My bike is bone stock other than farckles.. it's a 2013 recently completed all recalls (throttle and cam bus)..

so are you saying that if I want to take advantage of disconnecting the flapper I would need to rune it or do some other mods like exhaust and or air box?

Sent from my Pixel 2 using Tapatalk
No, you should be able to disconnect without any harm. It's full open at idle so definitely not the cause of your stalling. Also defaults to open via spring tension. I just think the benefits are negligible until you start doing some basic tuning items. It controls back pressure and noise level. Mostly just a DB killer for noise emission regulations.