Hi there, I've just bought a Yamaha TDM850 and before I bought it the previous owner told me he had just had it serviced and that the needle jets were worn and would need replacing soon. Searching around the TDM forums and the like, I found that it's a common problem for these things to wear quickly with these bikes. I think Yamaha calls them emulsion tubes. I'm assuming they are the same thing. What I want to know is, how hard is it to replace these things? Do I need to rebuild the whole carby (x2)? Everything I know about bikes has been learnt in the last few weeks but I have rebuilt and pulled apart just about everything in my car and have a good mechanical understanding. The last time I had a car with a carby however, was a long time ago and the only thing I did was tune it (very easy to tune a quadrajet with dual exhaust that doesn't combine anywhere). Will I need to get the carby's professionally balanced after doing this work? Can I do it myself? If so, how? Thanks guys.