My chain is still way into the green after 55,ooo km's. I wanna go 2 up in the back. Do I have to buy a new chain and front sprocket at the same time?

 

it is strongly recomended that you replace the sprockets and the chain at the same time. otherwise they don't mesh quite right. I replaced the chain without replacing the sprockets on my previous bike (92, yamaha Seca II) and got away with it. it make a little more grinding noise, but other than that, no problems after 2 seasons. but when I have to do it with my SH, I will replace them all at once. due to the much higher torque and HP, I don't want to tempt fate. I'm sure that the stresses on the SH chain and sprocket are much greater than on the Seca. 60hp vs. 105hp.

 

when i went 1down 2up the kit came with a new chain, but i needed a new one anyway.

 

I got a good deal on a 520 conversion, both sprockets a chain from hardracing.com. I forget what I paid but those guys meet or beat anybody's price. They recommend you get a race chain though when putting a 520 chain on a litre bike so it's a bit more money.