I now have a soon to be running 1976 Yamaha YZ400. It fired right up when I bought it, but it is in pieces all over the house; will be re-assembled in the coming weeks. I have some questions about premix oil and ratios. I bought a Yamaha YZ400C factory service manual. It calls for a 20:1 mix. That sure seems like a lot of oil! But I would rather mix a bit more oil than too little. I would also like to use a full synthetic oil like the Bel-Ray MC-1, http://www.belray.com/bel-ray-mc-1-racing-full-synthetic-2t-engine-oil , but it is sure expensive! What favorite oils are you using? Full synthetic or... ? What is the premix ratio are you using, with which bike, and with which particular oil. Any good reference articles, websites, etc.? Yes, let's start a PREMIX THREAD.