I went to a 15/47 (520 chain) set up after Kayla suggested it to me and I just wanted to give some feedback.

The acceleration is greatly improved the bike pulls a lot faster and is a lot of fun. If you use your bike for commuting it makes a huge difference in town traffic. We have a lot of 20MPH restrictions around here on top of the usual 30MPH. The bike is a lot happier at these speeds now. Before it was a pain getting a gear that wasn't labouring the engine or revving too high and meant feathering the clutch a lot. Now it is quite happy at both.

The only issue with the Renthal front sprocket is that it is narrower than the OEM (6mm vs 9mm) so I added some washers of the right size each side to compensate. I bought a big bag cheap so if anyone wants a couple give me a shout I'll post them on.

Thumbs up to Kayla she knows her stuff

Phew! I'm glad you're happy with the bits. I haven't found which front sprocket should be used yet, but that skinny one is the one that B&C list for the 400s. There will be one that is the right width somewhere though.

Hi Kayla, more than happy with the parts and the service.

You did offer to make up some shims which was very kind but I didn't want to muck you about, the washers were a cheap off the shelf solution.

Thanks to you I'm loving the bike all over again, feels totally different in a very good way.