Jump to content

04 Cr125r break in

Recommended Posts

Start and warm to the touch, check for leaks whilst running or off, then let it rip.

Share this post


Link to post
Share on other sites

or like many believe....do multiple heat cycles thinking that it breaks a piston and rings in. Hopefully, 5 or 6 more methods will chime in too.

Share this post


Link to post
Share on other sites

go for a 30 minute mild ride slow preferably a trail ride. let cool down warm up properly, now let it rip

 

Going too slow on a new piston/ring is a sure way not to seat them properly in the cylinder (glazed)

and have lots of blow-by for the rest of the piston and ring's useful life,

coating the ring with too much oil during re-assembly as well, a small dab of oil to the cylinder's surface is plenty.

 

Warm it up to the touch, then ride with moderate loads on the engine (no lugging / no super high rpm) varying engine rpms (not steady speed constant riding)

ride for 10-15 minutes, then let it completely cool off. 

 

Repeat above procedue once more and your engine is now ready to ride normally.

Edited by mlatour
  • Like 1

Share this post


Link to post
Share on other sites

Hopefully you checked for lower rod bearing for slop when you had the top end apart. Last weekend I freshened up the top end on my 01 cr125. It had 124psi before new top end install. After up too 130psi, good and tight. Break in was a few slow/mild laps at OMC in Norman, OK. After 3 5 lap runs I figured rings were good. The were a lot of A riders out that day so I figured I'd stay back and chase them down. Running a 15yr old 125 against -5yr old thumpers was a blast. On a 125 it's all about keeping momentum, rim the berms and drag the straights. The motor doesn't have the grunt like the 4strokes to park it on the inside line and come w speed. After 60 laps turning 1:10-1:15 lap times at the track, got home and my son wanted to ride around our backyard track so we did. 3 laps into our session the motor ingests a lower rod bearing roller. It ate the cylinder, head, and piston, but never seized. now I get to split the cases and do a full rebuild. And I'm down to my house bike 2003 klx110..

Share this post


Link to post
Share on other sites

130psi after a rebuild is quite low.

 

Anything under 150psi on a rebuilt or 'refreshed' 125 and I would have investigated why.

 

(actually closer to 170-180psi on late model YZ125's)

  • Like 1

Share this post


Link to post
Share on other sites

Hopefully you checked for lower rod bearing for slop when you had the top end apart. Last weekend I freshened up the top end on my 01 cr125. It had 124psi before new top end install. After up too 130psi, good and tight. Break in was a few slow/mild laps at OMC in Norman, OK. After 3 5 lap runs I figured rings were good. The were a lot of A riders out that day so I figured I'd stay back and chase them down. Running a 15yr old 125 against -5yr old thumpers was a blast. On a 125 it's all about keeping momentum, rim the berms and drag the straights. The motor doesn't have the grunt like the 4strokes to park it on the inside line and come w speed. After 60 laps turning 1:10-1:15 lap times at the track, got home and my son wanted to ride around our backyard track so we did. 3 laps into our session the motor ingests a lower rod bearing roller. It ate the cylinder, head, and piston, but never seized. now I get to split the cases and do a full rebuild. And I'm down to my house bike 2003 klx110..

how can you check?

Share this post


Link to post
Share on other sites

[quote name="dietch" post="13002452" timestamp="1458739

how can you check?

Side play of con-rod, visual/probe inspection thru oil slots, check rollers if they have dislodged from the cradle. I'm religious about mixing oil heavy to prevent smoking a motor, castor 927@32:1 if not a hair thicker. And as far as refreshed compression I've never had more then 130psi after a couple rebuilds. We'll see what it is after I get the motor rebuilt.

Share this post


Link to post
Share on other sites

Ive read that a hard break-in is good for some bikes, speeding up and gearing down so it "engine brakes" is good for seating the rings. Please correct me if im wrong

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×