purplefury said:i just finished rebuilding my rm 125 motor was wondering if anyone can tell me the best way to break it in as i have never done it before. I was thinking of just cruising around till i used like 2 tanks of gas, then slowly work my way up to full throttle with with the third tank.
wake_rider said:You just need to heat cycle the new piston a few cycles while running rich premix ratio.
-Run 16:1 premix
-Run your bike 1/4 throttle until it's well warm (15 min or so) then shut it off.
-Change oil.
-Run your bike up to 1/2 throttle till warm (again 15 min) then shut off.
-Change oil.
-Run bike normally with incremental runs of full-throttle until hot (20 min or so), shut off.
-Change oil
-Now drain remaining 16:1 premix, mix premix to your normal mixture, put in fresh sparkplug, and enjoy your fresh top-end!
BTW: While running through the heat-cycles, don't allow your bike to idle for any extended period of time. You're trying to saturate your piston rings with pre-mix oil and allowing them to seat into place while your piston goes through it's first expand/contract cycles by heating and cooling.
ellandoh said:regular mix
fresh oil changes are for the trans not the piston so no need to change
start it up, blip the throttle til its warm, let it cool completely.
start it up, ride it normally under 3/4 throttle til warm, let it cool completely.
start it up, warm it up as normal, LET IT RIP
everyones version is probably a little different, this one has been flawless for me for decades :cool:
wake_rider said:I'm simply listing what my factory service manual states the break in procedure should be. Ostracize all you wish, I'm simply following what the professional mechanics who work for Yamaha decided is the proper break-in procedure.
2005 YZ125 Service Manual said:BREAK-IN PROCEDURES
1. Before starting the engine, fill the fuel tank
with a break-in oil-fuel mixture as follows. (graphic not included but they recommend 15-1)
2. Perform the pre-operation checks on the
machine.
3. Start and warm up the engine. Check the
idle speed, and check the operation of the
controls and the “ENGINE STOP” button.
4. Operate the machine in the lower gears at
moderate throttle openings for five to eight
minutes. Stop and check the spark plug
condition; it will show a rich condition during
break-in.
5. Allow the engine to cool. Restart the engine
and operate the machine as in the step
above for five minutes. Then, very briefly
shift to the higher gears and check full-throttle
response. Stop and check the spark
plug.
6. After again allowing the engine to cool,
restart and run the machine for five more
minutes. Full throttle and the higher gears
may be used, but sustained full-throttle operation
should be avoided. Check the spark
plug condition.
7. Allow the engine to cool, remove the top
end, and inspect the piston and cylinder.
Remove any high spots on the piston with
#600 grit wet sandpaper. Clean all components
and carefully reassemble the top end.
8. Drain the break-in oil-fuel mixture from the
fuel tank and refill with the specified mix.
9. Restart the engine and check the operation
of the machine throughout its entire operating
range. Stop and check the spark plug
condition. Restart the machine and operate
it for about 10 to 15 more minutes. The machine
will now be ready to race.
Cheap ATF, couple of heat cycles, ride! I can change the tranny oil every ride at a 1.39/qt. The contamination from the clutch is gone after every ride. The Pro rider/mechanics that I know personally recommend consistancy and clean fluids over what the manual discribes for PRO riders.whenfoxforks-ruled said:Wake rider, there was a time I used to do the same anal/overkill things. A rm125 brand new, by todays standards needs minimal break in/heat cycles. More oil causes a lean condition/ unless you bother to jet for it. Breaking in the same as when it was brand new is not needed. The ring seats in minutes, just do not over heat it, or over due it! By the book, that ring is shot in hours! The oil, pay 25 dollars a quart and change it every weekend/race. Otherwise, no sniveling! Oil is cheap, other than Xamax! Then its just better insurance. ATF fluid is widely used, and cheap as it gets.
purplefury said:thanks for your help guys I will break in the motor next time i go riding. i cant break it in now because i live in a residential area and someone would call the cops.
BSWIFT said:Should have been more specific. Non pro riders need not follow the recommended hours as closely as a pro level rider. :think:
Nope. Aside from a truck full of parts available, and an adequate mechanic, what is the difference between the pro racing it and the guy out on the fire road? That book is sold with every bike in mind, not who buys it. It is the only true base line for keeping it safe, and running as it was bought. Some schedules this, that, or what ever. I can get more time if needed, but I also know the compromise, and I prefer to keep that on me, not someone else. A person can get 100 hours out of a ring, too what purpose? The ring may still be pushing adequate compression? The skirt is another story? How long does it take to push a cylinder out of round? Who gulped twice when they read that YZ break in, and the old rings went back into the mix, seemingly. It did not specifically say to use new ones? The pros top ends, 30 minutes plus 2 laps, not the 5 hours of bliss. I ask the guy that did the cylinder, with consideration! Break in, is break in, regardless of the operator. 100 hours from 1 rider to another, of course it is different, and regular maintenance plays a huge part. The books may not be perfect, or up to date, but its a start, and all we have.IndyMX said:However a non-pro rider should probably break in his engine a little more carefully than a pro rider.
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