I had no EXUP at all for a couple of years on my Gen 1, I just got used to it, just don't expect any power below 3K, it will pull away below that, but it is limp. Seizing open is a lot better than it seizing closed.
It sound's like you're saying - if it's broke don't fix it, it'll perform like shit at low revs, but don't worry as you won't know any better, there are two levels of shit performance you may be lucky enough to have a less shit experience !!!
In terms of advice for a new owner I'm wandering how beneficial this is, did you get your EXUP fixed, would you reccomend getting the EXUP fixed or leaving it seized?
Given that a major part of the appeal of these bikes is the ability to pull from low revs thanks to the EXUP (Ivans kit & 4 degree advancer also help) there is no way you're experiencing the bike as it was designed if you have a non functioning EXUP. If you got the bike cheap as a hack to faff around on then sure leave it as is and get your moneys worth but there are probably better options out there.
At the time I was in one of two riding modes, either just getting around, or going for it. In the first mode I didn't care about having little bottom end because I didn't really need it, I just rode around it, in the second, I spent all of the time above 6K so it didn't matter that the EXUP wasn't there. I just got used to riding around the lack of bottom end in the first mode.
I did eventually get the EXUP sorted but it was expensive, around £200 from what I remember, I know the EXUP cover plate was £145 on its own. Then £35 for the pulley, etc, etc. Please note, i'm not moaning, it is what it is.
What im saying is you just get used to it, just like riding a two stroke which has no bottom end till you hit the power. It isn't that bad, I only fixed mine because of the worry it gave in
very specific circumstances, like being in a bar in Belgium, after having parked on a very cambered road with a rucksack with so many beers in it, it had to be put on my back after id mounted the bike, a couple of beers which may have been drunk were involved too. I just knew that I would have been happier if I had the confidence to open the throttle at 1500 rpm and it would just go. I had the money to fix it well before this time, but I really didn't have a good enough reason to do it.
Plus (and I know that this flies in the face of popular opinion on here) my experience of an Ivanised bike is not as good as my dynojetted bike, Ive had both. But I'm hoping that I get to have a go on someone else,s Ivanised bike so I can join in the praise of this modification. It must be good, I just think I had a not so good one (no slight on "Ivan" here, just a "slow" engine). All bikes are slightly different I know, but side by side, my dynojetted bike had more grunt all through the rev range than my Ivanised bike. I sold my dynojetted bike to a close mate, and we did many roll on tests, I lost every one on the Ivanised bike.
I've since bought my old bike back and sold the Ivanised bike, even though it was a much nicer bike in much better condition.
Please note - I'm note after a row here, just saying what I have experienced.