Re: How to know when broken in? Fuel ratios?
Most these engines are poorly balanced and will shake themselves... and the rider to death... I usually buy bottom ends with balanced cranks and upgraded bearings which helps a lot. Thatsdax.com sells really nice balanced bottom ends and engines and I've ran these at 10,000+ rpm with no serious vibration issues... some of the ebay specials I've used tho are a totally different story and shook like crazy at just moderate rpms.