depends on what engine it is normally for first five hours dont ride over haif throttle, keep the load down and vary your speed, the next 5 hours keep it under three quarter throttle it takes a min of 10 hours to break in a motor some go as far as 15 hours , i would be changing your oil as well after the first 10 hours of use and refill with correct grade and dont overfill remember a carefull run in period will extend the life of the motor up to 3 times longer than a motor that was pushed hard from brand new dont over rev it allow it to slowly bed itself in and youll be rewarded in years to come
The myth is that it takes about 1000 miles of "babying" the new engine. Then change the engine oil again.
The best article I've read on the web concerning 4-stroke engine break in, can be found here: http://www.mototuneusa.com/break_in_secrets.htm--Rayengine break in is very important, proper break in will help ensure long engine life.
Break it in as if it is a new engine start by setting all your carb needles back to factory settings, even a bit richer if possible as long as the engine stays running without flooding. heres a good guide to go by http://www.rctech.net/forum/australian-racing/143096-nitro-engine-break.html
After the break in period it is not an issue.
This might not help... Get a new one.
For the first 1600 km's or 1000 miles on a new engine just use regular oil. The reason being is that you want MORE friction in the engine to help the parts wear properly for a good "break in", synthetic oil has such good lubrication properties that it can interfere with proper engine break in.
It is not the speed that will ruin a new car engine, it is too much heat. Do not drive fast or rev up the engine for more than a minute or two, then let it cool off. This is actually a good way to break in an engine.
To break a bad habit or get a new healthier one takes about thirty days.
With any car, it would be better to buy a new engine. You do not know where the used engine came from and how long it will run. Unless you have a very trusted repair person, a new engine is recommended.
3 weeks
It is a slang term for a brand new or rebuilt engine. It is also used to describe the break in period of a rebuilt engine during which you take it easy on the engine for the first 500 to 1000 miles.
Engine crankshafts usually break when there is too much pressure on them. Some have flaws and may break under normal use.