Break in

[juci2728]

Can anyone tell me if this sounds right. I just got done putting my top end back together and wanted to make sure I'm breaking it in correctly. First time out I ran it in and out on throttle till it got nice and warm. I then parked it and let it cool completely while I made sure all the nuts and bolts were still good and tight. then did the same thing 3 more times. I've got no smoke and no tapping grinding or leaks. Should I change the oil and call her good to go. Thanks

 

[1998yamahawarrior]

ya change the oil and run her but not wide open for long periods of time for just a little bit long and then have a blast

 

[warriorgirl09]

yall break engines in funny :/
but then again 95% of my work is 2 stroke race bikes

 

[bomber315]

yall break engines in funny :/
but then again 95% of my work is 2 stroke race bikes

how do you break in your two strokes?

 

[ratchracing]

yall break engines in funny :/
but then again 95% of my work is 2 stroke race bikes

how do you break in your two strokes?

In about 5 minutes ;D

Pretty much one heat cycle then your good to go. I usually break engines in pretty hard. When I rebuilt my 350 I rode it easy for about 10 min, let it cool, change oil/clean filter, then it was balls to the wall.

 

[warriorgirl09]

no you crank it and put put around for one full tank of gas, let it sit and cool. fill it up again and ride it that tank of gas put putting around THEN let it cool and fill it up and then balls to the wall.
the first 2 tanks are for seating the rings and bearings. then for the 3rd and 4th tank you ride it the way it'll be rode ( if you ride it light then break it in that way) if you ride heavy but break it in light then the first handfull of throttle you'll be rebuilding the engine.

 

[yamarider]

I don't know about 2 smokers, but for 4 strokes all the tests i've seen points to a hard break-in yielding better compression. It takes pressure on the rings to seat them against the cylinder walls, and if you spend the first 2 tanks of gas puttering around most of the cross hatching will be gone and the rings will be pretty much seated as good as they're going to get. After a rebuild i'll keep it around 1/4 throttle until the engine is close to normal operating temp and then run it pretty hard. Not bouncing it off the rev limiter or holding it wide open for more than a few seconds, but thoroughly running it through the rpm range and letting the engine slow itself down instead of the brakes, that's how I broke in my warrior, raptor 700, and a few other rebuilds and they all seated perfectly and to this day don't burn oil. The whole running it through heat cycles concept really doesn't have any science behind it, I think at one time somebody thought it was similar to hardening metal by heating it and cooling it quickly and would therefore strengthen the piston, but an engine's normal operating temps don't get nearly hot enough for that to actually happen the slightest bit.

 

[warriorgirl09]

2 strokes are alittle diff the 4 strokes... i break 4's in about like you do yama rider. but since a 2 stroker doesn't have as much lube as a 4 stroke you cant run it hard till the rings are seated good or you'll be re sleeveing the cylinder

 

[baddawg]

I think at one time somebody thought it was similar to hardening metal by heating it and cooling it quickly and would therefore strengthen the piston, but an engine's normal operating temps don't get nearly hot enough for that to actually happen the slightest bit.

You're right on that ,you would have to get that up over 600 F
before you start to get any changes.We cook carbon pipe at
1150 F and hold it there for 1-2 hours to stress relieve it.

 

[hatfield44]

interesting read
http://www.mototuneusa.com/break_in_secrets.htm

 

[bassballs818]

Thats a crazy article but very persuasive. Have you subscribed to the news link?

my only question to that whole thing is; does this method only apply to newer engines or will it work on older engines with new parts?

 

[dswwarrior350]

Break ins are often argued.... One big secret is not to lug the motor, break ins should be done on a flat surface and you should keep it up in the rpms.

For the first start up i would take it easy and ride around for maybe 10 mins or 15 mins But make sure during this first period that you do open it up a few times. Stop and make sure nothings leakin or etc.

After that you need to start running it through all the gears and revving it out. A huge secret is to let the motor slow the bike down. The vaccum created in the cylinder on deacceleration sucks all the shavings and **** out of the cylinder. Naturally dont beat the piss out of it, just get on it once in a while.

Dont change your oil till after the first tank of gas, changing it in 10 mins is just wasting money. Do not use synthetic oil to break it in

After the first tank of gas, ride it normal, change the oil (really i usually waited longer than this)

 

[ratchracing]

no you crank it and put put around for one full tank of gas, let it sit and cool. fill it up again and ride it that tank of gas put putting around THEN let it cool and fill it up and then balls to the wall.
the first 2 tanks are for seating the rings and bearings. then for the 3rd and 4th tank you ride it the way it'll be rode ( if you ride it light then break it in that way) if you ride heavy but break it in light then the first handfull of throttle you'll be rebuilding the engine.

Putt around for two tanks????? That would be 6 hours on my KTM. Crazy talk. I've always broke in a 2 stroke by going easy for 5-10 min, cool it, then go nuts. I've had 5 bikes and broke them in this way, no issues. Hell, my IT200 has about a gazillion hours on it and it was broke in this way.

 

[warriorgirl09]

i broke the blast in the way... wsm said 9:1 compression even on that piston and size bore... i got 9.5:1 on it i've ALWAYS broke my 2 strokes in that way... thats how my dad taught me and his dad taught him. hell i broke a yz 125 in for a kid like that a few years ago and he's still riding on that top end. he was out here the other day with it for me to clean the carb and rejet it and i put the compression gauge on it for kicks and giggles and it was reading 8.75:1 and it was a wiseco 10:1 piston.
anyway we all break em in diff and it all works and as long as it works there's nothing to fight about just throwing my way out there for anyone that wants to use it.

 

[hatfield44]

as long as it works

^that's all that matters

 

[bomber315]

mmmmm i dont mean to be an ass warriorgirl but im not too sure how your checking compression ratio with a guage.... maybe i am missing something here but the pressure shouldnt DIRECTLY relate to compression ratio... sure you can say something that has 180 probably has a higher compression ratio than something with 105 but that i dont believe that is right in all cases... if the porting sucks then you wouldnt beable to draw enough air to make the psi... i dont know tho maybe you have a different tool than what i have... enlighten me

 

[warriorgirl09]

i've got a screw in gauge that goes in the plug hole and tells me the psi and one of my friends at a machine shop does all the math crap for me to tell me my compression ratio

 

[91warrior]

im still confused, because you can have two identical machines side by side with the same compression ration piston in them but the cylinder psi pressure are not going to match identically so how would you calculate the pistion compression ratio from just knowing the the cylinder psi pressure? if an engine loses cylinder psi pressure over time from wear, how would you calculate that loss in pressure in the equation to figure out the exact compression ration piston that is inside the the particular engine? im not trying to be smart or anything im just wondering on how that is possible

 

[warriorgirl09]

hell if i know dude lol.... all i know is he told me to give him cylinder psi and he'll figure out the compression ratio for me :/ so i've been giving him the psi and he's been doing it for me.
idk anyway i gots treatments tomorrow ugh i dont wanna go!

 

[ratchracing]

If you know exact engine displacement (bore and stroke), as well as the size of the combustion chamber (volume in CC's of the engine when the piston is at TDC), then measure compression (in PSI with your guage) you can figure out the compression ratio.