Welcome on board Dan. Really sweet looking XTX you got there – low miles too.

Plenty of mods you can do to reduce the surging, a lot of which are either free, or cheap and easy to do. Here's where I’d suggest starting...

Join XT660.com supporters to access the “Ask Kev” 1:1 technical help section - http://www.xt660.com/payments.php

You’ve done the first one already – good move!

Check you haven’t got a bad TPS - http://www.xt660.com/showthread.php?t=948 Yamaha Recall

Check you haven’t got a bad ECU - http://www.xt660.com/showthread.php?t=519 Yamaha Recall http://www.xt660.com/showthread.php?t=8546 (How to recognise the different ECUs)

Twist-grip mod - http://www.xt660.com/showthread.php?p=154983 No Cost Mod

Cush drive rubber mod - http://www.xt660.com/showthread.php?t=12422 No Cost Mod

Adjust your CO - http://www.xt660.com/showthread.php?t=55 No Cost Mod

Adjust your TPS - http://www.xt660.com/showthread.php?t=56 No Cost Mod

Kev’s fuel mod - http://www.xt660.com/showthread.php?t=194

Good luck!

__________________