As a few 1200 Muttley owners have, or will have, found out, there is an engine management fault that pops up as EXVL. This is a butterfly valve in the cat which is just before the end can goes on (EXhaust VaLve). Whip the heat shield off and you'll see it on top of the short pipe coming out of the cat, it's a quadrant+spring+cable affair (like on a throttle) and serves no purpose apart from giving a bit of back pressure when the engine chugs along at low revs.
Due to it's position and our climate, the mechanism falls foul to the infamous rust beetle and seizes up giving the EXVL error. At first a generous squirt of WD40 and manual manipulation will free it off and away you go.
One sure fire symptom of it jamming is engine revs limitation, ie it will only deliver 7000rpm in 3rd, 6000 in 4th, 5000 in 5th etc. This is due to the ECU thinking it's broke and going into 'limp home mode', causing much frustration and swearing as you'll normally be well on your journey by time it crops up.
I spoke to Ducati Manchester today about a possible ECU flash to ignore the valve but they don't know of one and to cure the issue they suggested a new one. The sticky bit is they don't come on their own, you need to buy a whole new cat for £700ish. Balls to that! After a fair bit of tinterweb searching I found that you can't simply take the end of the cable out of the quadrant because there are sensors that look for the cable being pulled back into position. The problem isn't with the butterfly, the quadrant or the cable, it's the shaft they are mounted on (with the 8mm thread on the end) becoming rusted up and not turning. Some forum threads suggest removing the shaft and replacing with a stainless steel one without the butterfly, this involves some tricky grinding as the original butterfly is fixed with 2 small screws which are spot welded in place so you need to get a grinder inside the exhaust to remove it.
This is how I overcame the problem:-
1. Remove heat shield, end can and rear foot rest hanger off (for ease of access but no real need to).
2. Remove the 8mm nut and tab washer, 12mm spanner as it's a fine thread.
3. Remove cable from quadrant.
4. Remove quadrant (the spring isn't under loads of tension but be careful).
5. Drill out centre of quadrant to 8mm (opening out the oblong hole already there).
6. Build back up in reverse order (apart from the heat shield).
The quadrant should now turn freely on the shaft without the butterfly moving.
7. Drill a 2mm hole through the shaft (on the flat part) above the nut (to accommodate some lockwire).
8. Position the butterfly in the open position and secure the shaft in position with lockwire using the hole you've drilled (there's a handy bit of bracketry there perfect for this).
This serves 2 purposes, it stops the butterfly working it's way round and closing the exhaust off and it also stops the nut from coming off.
9. Replace end can, heat shield and peg hanger.
10. Test. Quadrant should turn easily and then return when ignition is turned on.
This procedure took about an hour without any problems, swearing or blood loss, I hope this helps anyone who suffers from EXVL. Please feel free to share on any other forums.
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