I've not had this problem on my 20,000 mile, 2002 but, I did notice that the tickover got a little slower when the engine was getting plenty hot - beyond where the gauge routinely sits.
I decided to remove the spring that holds the throttle arrangement against the CSM operating plunger (this was many years ago, so excuse the vagueness, but I can photo the spring I'm talking about - it's safely stored in the garage).
My bike, without this spring, starts fine, but the engine needs some controlling on the throttle for a short while, to stop it stalling. But, I'm a fair-weather rider, so colder days may be much more, er, demanding, to prevent a stall! But this is only as I remember cold-starting bikes before fuel injection became common.
Also, setting my bike apart from most others, I have my tickover set to 1300 to 1400 revs (Yamaha say 1200 to 1300, I think), because I find it reduces the engine braking a little, making for smoother town progress. Well, for me, anyway.
What I'm thinking is, can you remove the CSM, by-passing (joining together) the coolant pipes, so you can still use/enjoy the bike whist tinkering/fettling the CSM? I've never done this, I should add.
Is it not the case that the fast idle is as keen to lift the tickover as it is, so as to get extra exhaust gas through the catalysts; to get them up to operating temperature quickly, so reducing emissions? I have an idea the cats work best at around 600C, and they are a long way from the engine, so getting them hot from a cold start isn't going to be quick without the engine putting some extra gas (fast tickover) through them.
If you've replaced your exhausts with aftermarket, then the cats aren't there anyway, so the feature, to the extent it works in normal use, is partly redundant anyway, I suspect.
Happy to be corrected of course! I'm an infrequent user of this bike, so not a regular visitor to this site! I've recently rejoined with a new ID, as my sign-on details and email address had all been lost/changed from my original joining in 2006.
Edited by Boosh, 25 July 2023 - 11:45 am.