When I brought my 19 plate Multi 1260 Enduro last year I was told by the vendor that it was fitted with an 'Exhaust Flap eliminator', which to be honest I had to work out what that was. I immediately realised there was some sort of minor issue with the bike, as there was a flat spot between 3500 and @4250RPM, right where the valve is doing it's bit to cut noise at the 4K test. I dug around and found a Healtech unit plugged into the loom where the valve servo should have been plugged in, which should have been a good thing, but this one had been resting on the exhaust and was melted: I brought another one expecting the issue to go away, but it had no effect at all, I took the exhaust silencer off and found the valve was fully open and the cable from the servo disconnected. Having heard about plug leads on these breaking down I replaced all 4, dropped new plugs in as well, and the flat spot got a bit better but didn't completely dissapear. I then sort of got used to it, and avoided that part of the rev range thinking perhaps the Healtech was causing it. Anyway, fast forward to Friday afternoon I was doing a little bit of tidying on the bike, had the exhaust cover off and thought, 'haven't I seen somewhere that you should wire the flap open not just leave it disconnected?' So added a lockwire to hold it open: Managed to out for a short ride this afternoon and what a difference, no flat spot at all. Obviously the exhaust gas flow at that revs was closing the valve. I'm sure everyone apart from me already knew this, but I'm now a happy bunny this evening.
Now, this is where I struggle in my comprehension. The default position for the valve is open. The servo motor, when activated, closes it by pulling on the cable. Once activation has finished the spring on the valve pulls the valve open again and resets the servo motor. It’s a strong spring. How could the exhaust flow cause it to close? Even if the exhaust flow was powerful enough to close the valve against the spring why would it become less powerful as the revs rise beyond 5000rpm such that the valve can spring open again? I suggest your flat spot is more due to the fuelling map also leaning out at the same point the valve closes ie 3500-5500rpm in order to get the bike through the then emissions tests. ESE’s are there to overcome the fact the valve invariably rusts and seizes and to trick the ECU into thinking all is hunky dory and stop it from throwing an engine management light.
Paul, Honestly, the difference wiring it open was really noticeable. I made no other changes at the same time and the flat spot I've been putting up with was gone. The spring, on mine at least, really isn't very strong at all, the disconnected valve is very easy to move with very little pressure and I doubt there is enough force in it to drag the servo motor back to it's rest position.
You already have your solution now but i thought the most effective and zero cost method was to remove the 2 screws that hold the butterfly valve onto the spindle that the servo acts upon. The control electronics can then do its thing against a serviceable servo ( or not if its rusted) /cable seized. etc and it makes no difference.
Yep. I had a look down the hole and thought removing the flap has got to be the plan for the future, but locking the flap open has proved a point. It looks easy to undo the two screws and remove the flap, however they are a few inches down the hole and have been in there 7yrs now so are unlikely to come out easily. I can see at least one screw and the flap itself disappearing down the hole and me having to remove the whole exhaust to tip them back out. I don't know how long the original Healtech was fitted to the bike, or why it was fitted. The cable looks completely seized, and I don't know if the servo works any more. If I'm ever deep enough into the bike fixing something else I might see what state it's in, but it's so buried I'm not going looking for it unless I have to. Perhaps if I change the exhaust, or remove it to clean it up, which it desperately needs, I'll have a look.
Many years ago when I first got my 1098 i looked into methods of overriding the exhaust valve. A free method i found was from a chap on ducati.ms. remove the cables and thedrum from the servo and fit a bar on the servo motor in place of the cable drum. I ran that for a long time but then went to healtech because I removed the servo and used its location to mount the reg rec and a power supply for phone etc. 1098 has gone now but the servo is buried in the garage somewhere. If i find. It i will upload a photo
I'm surprised the valve still moves given the visible corrosion. I had a car with an electrically operated valve on one of tailpipes to make it quieter at low speeds etc. I had read on various forums that jamming it open liberated a small amount of extra power whilst not making much difference to the noise and, that the recommended method was to disconnect the piston that pulled it and fit a jubilee clip around the pivot shaft to hold it open and that by leaving the piston free to move it wouldn't show any faults. I had it like this for 12 years with no bother until I sold the car, at which point I decided to put it back to standard but the flap was now seized in the open position so I left it. That said, I think the best way to eliminate it is to change the pipe for something straight through which is definitely what I would do on a bike.
When I got my 899 the valve was seized shut (no wonder the last owner crashed it) so I cut the lot out and welded in a bolt where the spindle hole was. Job done. Ps. I read the title and thought you’d had your ears done
I was actually hoping for more from my thread title, but at least a couple reacted. There is a classic Viz strip where Finbar Saunders and his mother are camping. The neighbour wants to lend them a piece of equipment and says to the mother "Open up your flaps I'm coming in" A proper ooeeer fnarr, fnarr, moment.
