Author Topic: Break in! (Read 2095 times)

doordie · « **on:** December 19, 2004, 03:42:40 AM »

Hi Guys!

How to break in a new piston/ring cylinder wall?

Teory is:

Ringtension only skrab the oil and let no oil in combustion chamber,not seal.
The real seal is when the gaspressur go over the top of the ring and gets behind it and force it outward against cylinder wall.
New rings are not ?perfect? and have to worn in quite a bit in order to seal all the way around the bore (360*).
New cylinder have honed crosshatch pattern who is like ?peaks? and have to wear down to get proper seal.

So, if you want to have a engine who has a ?works? sound and power and no ?moped? with 10% lower hp.

RUN IT IN HARD FROM FIRST START!

Why so?

If the rings aren?t forced against the walls soon enough, they?ll use up the roughness before they fully seat around the bore. And the force is from air/gas mixture ,so you have to ?open throttle? to get enough of pressure for proper ring seal.

This is my break in:

Go to a racetrack if you can, the best break-in enviroment.
Warm the engine up completely.
Go for a easy lap and then into pit and turn off the bike for check-up leaks.
Then you go for a 10-15 min practice session.
Stop and let it cool down for 15min.
Do it over again.
And again.
Now race ready!

Why is the race track the best enviroment to break in, because of the combination of acceleration and decelerartion.
So with a birst of accelerartion followed by deceleration for short times make the rings press good against cylinder wall and let it cool nice afterwards by deceleration. THIS is the best break in procedure you can have on you new rebuild topend.

Never ,never start the engine in garage and not followed by this loaded break-in after a good warming up!

You will get a poor seal and slow engine.

Just my 2 cent !

//doordie

KXcam22 · « **Reply #1 on:** December 20, 2004, 11:31:10 AM »

Doordie,
Well said!!!! I couldn't agree more. In addition to ring sealing, I have always felt that it is important for the engine to get those short peak power runs to heat the piston so the high spots will wear down earlier and not seize later (when racing). Cam.

doordie · « **Reply #2 on:** December 23, 2004, 06:21:29 AM »

Have to say a "few" words more about rings.

They have more work to do then only seal.
It`s transform heat from piston to cylinder wall.
This is just so importent as the sealing.

Some tips:

The place were the pistonpin is located is were
the ring have easiest to sieze.
(This because of less mass of the ring just there).

If you have black spots on piston below rings
(over wristpin).You have a blow-by just there
and the ring haven?t sealed 360* correct and
this because of wornout rings(or not properly
breaked-in).

Do not take away the second ring and think
it will run better with less friction,It`s only over
8000 rpm you gain something,and you lose very
much sealing below that rpm.

//doordie

doordie · « **Reply #3 on:** January 08, 2005, 11:45:36 PM »

HI Guys!
I?m just to "START" my new rebuilt iceracer(new design of head,lighter wristpin,new modified KIPS and of course new piston) and I will share some more of my thoughs in "breaking in".

You don?t need to agree!

I will NOT use more twostroke oil then normal (3%)!

Why?
It effective lean the jetting and your previos "safe" jetting set-up is F..K`up

I will start the engine and as soon is run rideable I go for my previous post how to break-in and will not stop before it`s finnished.

Wish me luck please with my TOO many mods at the same time!

//doordie