Hey dude
OK - well so long as it was running OK when you got it, the mods aren't, in themselves, the problem...
Often the way with an older bike if you can't fix it yourself...
Common problem that sort of thing.
That's a really weird thing for them to do, given that the jetting was right for the filter and exhaust -if it was suddenly running too lean, that would mean a new fault, not that some magic had happened and suddenly the jets had changed size in the night.
Hmm. Sounds like a bodge fix to a symptom of a problem, rather than actually fixing the problem itself...
What points? It's a CDI ignition, no points. Maybe a problem with a pickup coil, that could cause a high engine speed misfire. In fact, my DRZ currently has that exact problem in Mongolia, but that's another story... No surprise it was now running very rich, there's a plastic restriction in the inlet of a bike that was previously jetted correctly!

Sounds like they'd ended up setting it up too lean.
Interesting - I think maybe you have an intermittent intake air leak, which when it's leaking leans out the mixture (hence them putting a restrictor in the inlet as a bodge) and when not leaking, richens it back up again. If they'd leaned off the jetting, it'd then run properly with the restrictor so long as it wasn't leaking, but when extra air was getting in it'd be far too lean.
Yes, but on the over-run (closed throttle) it's likely to be an air leak into the exhaust, I don't know about the SV, but on the TL1000S and TL1000R there is a gasket in a joint between the rear header and the rest of the exhaust system that fails and causes this exact same problem.
Fair enough, let us know how you get on....
Intermittent air leak into the intake (inlet rubber between carb and cylinder head, leaking scottoiler install, balance pipe perished (if there is one, I don't know for sure on the SV)
Only you can answer that question as it's about your piece of mind. To be honest, I'd be more interested in changing bike workshops than changing bike, right now...

__________________