Hi guys, I would like to change out the stock 18 inch rear wheel on my gsxr400 .....for a more popular 17inch size with a view to using it for track days. Can anyone offer advice on which wheel would be the most suitable......,with the least modifications......e.g......would and XV650 rear wheel slot in????

I don't think any wheel is slip in with no buggering around. I used a 400 Bandit wheel (17x4.00) on my '87 gixxer and had to make up a different spacer on the brake side and take 3mm off the sprocket carrier and new spacer. The big issue with wider wheels is the sprocket alignment and tire width. You can make up an offset front sprocket but too wide a tire means a new swing arm (BIG hassle). One of the newer 250's might be worth looking into.

You need the braced swingarm, with 17" wheel spacers and bits and bobs. Otherwise your bike will ride too low, and they are already far too low as std!