wow thks all for the advice..
what temperature in celsius shld i warm the bike up to, before starting the break in?
so i'll put in some high rpms (ie: 8-9000?) for each gear change.. then engine brake down to a stop..
do this maybe a couple of times for the first 20miles..
get a change of mineral oil to flush out all the iron bits..
then after that it will be just taking it easy on the engine until the 1600kms are up..
before going with synthetic oil..
anything fundamentally wrong with this?
It's more about making the engine work hard, rather than high RPM. Engine load is what you are after. Snap the throttle wide open with ~4000 RPM on it, and accelerate to 8-9000, then snap it shut, and coast back down to 4K on engine braking. I would do this in 3rd, or 4th gear rather than 1st.
You want the motor to have to work hard, for a short period of time...... you also want to avoid super high RPM for extended periods, until the bearings have gotten smoothed out.
The rotating parts of the motor (crankshaft, cams, transmission shafts) don't run in the dead center of the gaps between bearings.... they ride on a wedge of engine oil, that rides on those bearings. Sort of like dough in front of a rolling pin. The oil film is thinner where the pressure is highest. That can be very thin, indeed.
So thin, that the high spots on the bearings, and rotating parts can stick through. If the contact is VERY short duration, the high spot gets knocked off, and flushed away with the engine oil. Longer metallic contact will weld some of the bearing material onto the roatating part.... which blocks oil flow, which causes more heat.... which welds on more metal.... like a snowball going down hill.
If you only go into the high pressure/highly off center region for a few (2-3) seconds, you will 'get away with it'..... that is plenty of time to make the rings work against the cylinder wall, and make the best seal possible.
30 seconds, you could do some more serious metal transfer. So you do the 'hard' runs; then go back to something very much like what the owner's manual says..... don't make it work too hard, and don't run it at the same RPM for any great length of time.
Most go through engine break in on traditional dino oil.... that's almost certainly what Yamaha put in there when they put it together. There are motorcycle manufacturers who run synthetic (mineral) oil from the very start. I run dino, because it's less expensive. If you are going to change the oil at 600 miles, and again at some point less than 3,000 miles..... Dino will cost you less, and do the job adequately.
