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breaking in pistons


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hi.

my shee is bored over 0.30 over with Wiseco pro-lites and a new bore. the engine is basically stock except for the bore and pipes. what process should i use to break it in properly? are there some general rules i should follow? i mixed my gas pretty thick just to be safe thx

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True...but there are quotes in there about breaking it in.

You will find it varies just as much.

 

Some will say, mix more oil, keep the RPMs varying for the first tank of gas, and don't go wide open throttle for more than a few seconds.

 

Others (myself included) will say heat cycle it a couple times, check the torque specs....and beat the living tar out of it....

 

And it varies between those ways.

 

You will find there are lot of opinions on this and other boards. Obviously, they vary from one extreme to the next. There is no one clear cut way for anything anymore...

 

I use what's worked for me from my years of experience....and I'll stick to that...just as anyone else should from their own experience.

 

Sorry for the open ended response...but, with a little searching, you'll find I'm dead on about no one being dead on...:)

 

:lol:

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The heat cycling is definately a good idea, then check the torques. After that, just ride it around a little blip the gas a few times first, before nailing it. The next time I do a rebuild I am going to run the oil a little rich the first tank, not sure if it matters, but I have some reasons to think it may. Basically the main thing, definetly since you have forged pistons, is to make sure it is fully warmed up before beating it. Aluminum expands more than metal, so your psitons should be set with larger PTW clearence than a stock one will, once it warms up it is good to go. Now if they are cast pistons, still warm it up, but it is not as critical.

 

I agree with above you are going to get no one best way to do this, just personal opinions. Even a reputable shop is someones opinion.

Edited by fastcar01
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Others (myself included) will say heat cycle it a couple times, check the torque specs....and beat the living tar out of it....

Agree 100%! Did this when the bike was new, First teardown 2 yrs. later showed zero problems.

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Heat cycle is a whole other can o worms with differing interpretations. Some guys think that by letting the motor warm up (gentle riding) then cooling down over and over will temper the metal parts in the motor. Obviously, this is BS- the manufacturers tempered the parts in the production process, a method which uses scientific formulas to dictate a slow and precise heating, then cooling of parts to optimize the strength and flexibility of a particular type of metal part.-Which varies widely as determined by the type of metal, thickness, and strength vs. hardness requirements. In no way will a bike motor recreate these conditions nor does it need to; it's been done before the parts were installed, at much, much higher temps. I do believe in a heat cyle as a way to properly seat gaskets (namely, the head gasket), causing it it to soften and conform, which then will usually require a retorque. This being a quick ride with some rpms and temps, then back to the truck and hitting EVERY available bolt or nut with a torque wrench or good rule-of-thumb tightness to make sure nothing is going to leak or rattle loose later. Then you are done, ride it hard. Tho it doesn't hurt to run the mix and jetting a bit rich when new!

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My take on heat cycle is warm it up, blipping the throttle slightly...and letting it idle too, until my pipes AND head are very, very warm.

 

I shut it down, have a smoke, drink a coldie, and do it again.

 

I might go for a quick, quick rip...then park it and retorque.

 

I agree...that whole heat temper thing is BS....

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Ya, the whole heat temper thingy is crap.............. :flush: . I agree with the above add a little more oil than usual warm it up a few times to get the metal's expanded and seat the rings, and check torqe specs. Then after about half the tank start blipin' it around and then the second tank ride it like ya stole it.................. :headbang:

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