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Yz 125 break in

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I just replaced my top end and am trying to break it in properly, I let it idle two times for 10 mins with a long cool down period. The part im stuck on is that ive been reading about break ins and people say they run at 50 60 70 80 90 then 100 for the break in with cool down periods between all of those. Is that necessary? what is your break in method? 

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Run it hard for about 20-30km without over revving or lugging the motor. i.e wide throttle openings at mid range revs. don't rev the tits off it. Don't go wide open from idle in top cog.

 

Then ride like normal.

Heat cycle and gentle break ins are just bullshit.

 

Seating the piston rings is your main objective and riding like a grandma aint gonna do it.

Edited by SatansReverence
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I've heard someone that works in engine development at a major auto manufacturer say that with modern plated cylinders, coated pistons and alloy piston rings, engines are 95% broken in in the first minutes of running. 

My opinion is a couple of heat cycles, one ride under moderate load, then have at it.

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Run it hard for about 20-30km without over revving or lugging the motor. i.e wide throttle openings at mid range revs. don't rev the tits off it. Don't go wide open from idle in top cog.
 
Then ride like normal.
Heat cycle and gentle break ins are just bullshit.
 
Seating the piston rings is your main objective and riding like a grandma aint gonna do it.

What do you mean by 20 - 30 km? And what does top cog mean? Thank you

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As in distance ridden. 

 

Basically about half an hour of riding on open tracks.

 

top cog = top gear.

 

Just keep the revs at mid range and open the throttle right up.  go through the gears a few times.

 

 

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As in distance ridden. 
 
Basically about half an hour of riding on open tracks.
 
top cog = top gear.
 
Just keep the revs at mid range and open the throttle right up.  go through the gears a few times.
 
 

After the rebuilt it has really good compression, will the aggressive riding during break in hurt that?

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NEVER BEAT IT LIKE YOU STOLL IT IN BREAK IN.

Couple 5 minute heat cycles, cool between, then a ride it easy load heat cycle, then BEAT IT!

 

I have over 25 engines out there going strong with this method. 

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NEVER BEAT IT LIKE YOU STOLL IT IN BREAK IN.
Couple 5 minute heat cycles, cool between, then a ride it easy load heat cycle, then BEAT IT!
 
I have over 25 engines out there going strong with this method. 

Ok since I already let it idle twice should I just ride and not go past half throttle for a bit? Then will I be good to ride normal?
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2 minutes ago, mritch8 said:


Ok since I already let it idle twice should I just ride and not go past half throttle for a bit? Then will I be good to ride normal?

Exactly. Go on a putt and run through all the gears with light load. Let cool again, and then let her rip. 

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12 minutes ago, P84ONE said:

Exactly. Go on a putt and run through all the gears with light load. Let cool again, and then let her rip. 

by let her rip can I go full out after I putt around for a bit and let it cool?

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3 hours ago, mritch8 said:

I just replaced my top end and am trying to break it in properly, I let it idle two times for 10 mins with a long cool down period. The part im stuck on is that ive been reading about break ins and people say they run at 50 60 70 80 90 then 100 for the break in with cool down periods between all of those. Is that necessary? what is your break in method? 

Rebiuld, start let warm up clean out. Then balls out 👍 the best it's going to be why waste it. When I was racing full time is do alot of them night before then practice right into racing.  If it old cast bore or steel sleeve then alitte more break in procedure but not much. Giver some gas man:ride:

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23 minutes ago, mritch8 said:

by let her rip can I go full out after I putt around for a bit and let it cool?

Exactly. Remember to ALWAYS let it warm up before EVERY ride. 

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16 minutes ago, Motox367 said:

Rebiuld, start let warm up clean out. Then balls out 👍 the best it's going to be why waste it. When I was racing full time is do alot of them night before then practice right into racing.  If it old cast bore or steel sleeve then alitte more break in procedure but not much. Giver some gas man:ride:

Yes, if you are a racer, and money in your pocket, and the top end will be rebuilt by next race, GO FOR IT. 

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1 minute ago, P84ONE said:

Yes, if you are a racer, and money in your pocket, and the top end will be rebuilt by next race, GO FOR IT. 

Yes good point I actually thought about that after I posted. I'm all about being safe and tell customers let warm up cool down couple times . Normally their not fast enough riders to have any worry about long as not a wide open road runner lol hey why the change of name doc? Jw. 

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2 minutes ago, Motox367 said:

Yes good point I actually thought about that after I posted. I'm all about being safe and tell customers let warm up cool down couple times . Normally their not fast enough riders to have any worry about long as not a wide open road runner lol hey why the change of name doc? Jw. 

Figured I went from PALMER84ONE, to Gary YZDOC, to P84ONE to change things up. The CA forum guys usually haunts me with all the jerks in there. First one I had since I started here years ago. I'll probably just go back to something like The AZ YZDOC when I move to AZ. 

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9 minutes ago, P84ONE said:

Figured I went from PALMER84ONE, to Gary YZDOC, to P84ONE to change things up. The CA forum guys usually haunts me with all the jerks in there. First one I had since I started here years ago. I'll probably just go back to something like The AZ YZDOC when I move to AZ. 

Ahhhhh ok . Change is good sometimes for sure 

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I'm another believer in let bike get good and warm then go beat on it 

 

Never had an issue usually actually get better ring seat that way. Proven with 5-10 psi better on compression gauge on my 125s since I started the beat on it method ,discovered due to topend rebuild overnight between racedays.

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I have one for you. I heard of a guy that believes in not running coolant in it for the first two heat cycles, and letting it get egg fry hot. Needless to say, he rebuilds engines frequently (same engine, top ends). 

I just follow the same process that my senior racer told me, and it has been fantastic since. 

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Pretty sure they are run at the factory no coolant for break in before engine is even put in the frame?

 

could be urban myth though

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