Motor break-in period question???

[txsteele]

Just bought a new KX250F and the dealership Service Dept told me to “heat cycle” and baby it for the first 10 hours.

 

I mentioned this to my regular MX mechanic who said that was way too cautious. He told me to heat cycle it 3-5 times and then ride it.

 

What say you?

[CDNSXV]

The rings need to seat to the cylinder.  The only way to do that is to put the motor under load ..... accelerate hard in the higher gears.  

Factory "break in" is a load of BS only designed to stop you wadding up your new bike because you are unfamiliar with it.

[pomoco]

Just ride it. maybe stay off the rev limiter the first two outings.

[William1]

Google MotoTune.

After 15 minutes of run time, the rings are seated, good or bad.

[69fastback]

Yep. If the rings aren'ht seated after 2 heat cycles, they aren't going to seat. Ride the piss out of it. 

[Cullins]

10 hours! We have about 3-4 races on a bike before that!?

Just ride it. 

A real test was done here. 

 

[Hammy.]

Ive had many new bikes...both 4t and 2t...right away rode them full gas. Never an issue. 

[GuyGraham]

Done multiple new bikes and multiple rebuilds the mototune way any never had an issue with any of them.

They all have run strong and burnt no oil

 

This heat cycling thing is another myth. You are not getting the engine hot enough to do anything to the metal (from a metallurgical aspect) inside from the exposure to normal running temps.

 

Lots of short sharp acceleration to load the rings to get them to seat, and your done in a hour

Edited July 7, 2019 by GuyGraham

[GuyGraham]

On 7/6/2019 at 3:44 AM, CDNSXV said:

The rings need to seat to the cylinder.  The only way to do that is to put the motor under load ..... accelerate hard in the higher gears. 

That should be lower gears...higher gears will cause engine to lug somewhat. Engine needs to rev freely

[rodent]

"Break in's"  are overrated    ?

Not a motorcycle, but same same ?

 

 

 

Edited July 7, 2019 by rodent

[UPSWR450]

7 hours ago, GuyGraham said:

That should be lower gears...higher gears will cause engine to lug somewhat. Engine needs to rev freely

If your going fast enough in the higher gears it will rev plenty freely

[UPSWR450]

My 07 wr450 I got new in 07. I think I rode it around the block and back roads a couple times for the heat cycling. Then have been ripping on it ever since 

[BOAB]

Depends on the engine.  A build my son just finished would have been destroyed if he just drove it.  Flat tappet cam in a 4.6 liter Jeep stroker.  That cam and lifters has to be broken in a certain way.  So yes, break in is important, more important on some engines that others.

"Flat Tappet Camshaft Break-in Procedure. As a point of interest, the most critical time in the life of a flat tappet camshaft is the first 20 minutes of break-in during which the bottoms of the lifters "mate-in" with the cam lobes. There are some oils with additive packages that are better for camshaft break-in."

Edited July 7, 2019 by BOAB

[CDNSXV]

8 hours ago, GuyGraham said:

That should be lower gears...higher gears will cause engine to lug somewhat. Engine needs to rev freely

No.  Accelerate hard in a gear or two high.  Engine need load on the rings.  Free revving in low gears doesn't do that.

[Rolls7]

16 minutes ago, CDNSXV said:

No.  Accelerate hard in a gear or two high.  Engine need load on the rings.  Free revving in low gears doesn't do that.

Doesn't combustion pressure provide load on the rings? Lots of combustion going on during free revs. Hard acceleration in a too high a gear loads crank and rod bearings. That's not so desirable.

[GuyGraham]

20 minutes ago, CDNSXV said:

No.  Accelerate hard in a gear or two high.  Engine need load on the rings.  Free revving in low gears doesn't do that.

From Mototune

The main thing is to load the engine by opening the throttle hard in 2nd, 3rd and 4th gear.

Being in a gear or two high will result in labouring the engine where what you want is it to rev, then closed throttle, to suck the swarf off and be washed away by the oil

[pat22043]

Run it thru the gears at maybe 3/4 throttle for the first 10 minutes. Vary speed and throttle. Then quick bursts of WFO for the first hour. After that, go. Change the oil maybe 5 hours in.

[69fastback]

6 hours ago, BOAB said:

Depends on the engine.  A build my son just finished would have been destroyed if he just drove it.  Flat tappet cam in a 4.6 liter Jeep stroker.  That cam and lifters has to be broken in a certain way.  So yes, break in is important, more important on some engines that others.

"Flat Tappet Camshaft Break-in Procedure. As a point of interest, the most critical time in the life of a flat tappet camshaft is the first 20 minutes of break-in during which the bottoms of the lifters "mate-in" with the cam lobes. There are some oils with additive packages that are better for camshaft break-in."

Meh, breaking in a flat tappet cam doesn't share a lot with this scenario. 

[69fastback]

14 hours ago, rodent said:

"Break in's"  are overrated    ?

Not a motorcycle, but same same ?

 

 

 

When I got the engine in my Mustang, I started it up, did a leak check,and drove it about a mile down the road. I pulled in the shop, loaded it on the trailer and went to the track. I made one motor pass and then started spraying the hell out of it. 2 heat cycles and they're good. 

[BOAB]

1 hour ago, 69fastback said:

Meh, breaking in a flat tappet cam doesn't share a lot with this scenario. 

I know, but it was an extreme example of the fact that oftentimes break in is important. ?