So you say tyres, rego, a service and a good clean are what is needed to get it up to spec hey!!! Let's look at it mathematically and se wht it looks like???
Rego $500
Tyres $400
Service $180-$320 (depending on major or minor)
Advertising $100
Total $1180-$1320 depending on service.
Plus you need to calculate your time. (if your time is worth something to you?) Let's say 5 hours work for you with cleaning, transport time, ad writing, telephone call recieving time, procrastination time from the buyers, fuckaround time when they don't turn up etc., etc.,
I reckon they will probably pay you 2500 for it as it is! (I hope I havn't offended ya?) and with the spend that's needed on it, I reckon that's about right. Anything more than that and you're having a win. Add the reco costs to that, and you might save yourself $500 to $800 if you spent the time and money on it and traded it.
OTOH, if you tarted it and sold it privately, it might reach $4000-4250 for it if you get the right buyer, which would mean around $3000 real for it after the spend.
To my mind, I would give it a wash ( a clean bike always looks like a bit more money even to a trained buyer, they are human too), and trade the sucker in and just haggle the best deal you can from them.
Make sure you run around a bit before you sign, and see if someone doesn't make a mistake or just desperately need some cash to pay some wages!!!! Sometimes you can hit someone at an opportune time, when they are being hassled to pay a big bill, or are a bit cash poor and need some wages money!!!!!!!
I know at times in a motorcycle dealership I ran years ago, that the owner would sometimes let me know that certain bikes would be happily negotiated on. Especially if I wanted paying that week!!!!!

"I hate to advocate drugs, alcohol, violence or insanity to anyone, but they've always worked for me" Hunter S. Thompson.
There are really only two questions in life. 1.Which way do i go? 2.What is the lap record?