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Breaking in a new crank

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I plan to put a new crank in my 05 in the winter months and was just wondering what you guys thought of break in procedure? i know that the break it in hard, with the dry rebuild method is well documented for top end rebuilds but what about new cranks with and without, new top ends?:)

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Just ride the bike as you normally would... And when you do tear down a bike to put in a new crank, you always stick on new rings on the piston as a minimum. And hone/do it dry. Each time the piston comes out of the cylinder you need new rings and a dry assembly to get the rings to seat again.

I have done three cranks on CRF250's before, and that is how I have gotten the person to "break in" the bike. Just ride it hard as you normally would with engine breaking...

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but when u r breaking it in i know u want to ride it hard but are u supposed to stay off the limiter or is it ok to hit the limiter?

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Its fine to hit the limiter when "breaking in" :) -- Kinda part of the ride as you normally would/ ride it hard, but use engine breaking. -- Should only need to worry about using some engine breaking for the first half dozen or dozen laps at the track, or a moto, whatever you wish. Then everything is fine.

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Here is the procedure:

Hone the cylinder (ball hone or brush hone) in soap/water. Clean out with break clean and paper towels until there is no black on the paper towels. I have a 3.5” ball hone in 180 grit. --- This hone size is for a 250f.

Wash the piston/rings in soap/water, spray off with break clean and let air dry.

Install the rings on the piston. Use proper ring staggering - follow the manuals staggering method - Be really careful not to get any oil residue on the piston, rings, or cylinder. Keep your hands wahsed

Install one clip on the piston. - the right side one.

Install the piston on the rod, use a light coat of oil on the wrist pin only.

Install the other clip, be sure not to get any oil residue on piston/cylinder.

Install the piston in the cylinder. Compress the rings with your hands and very carefully install it. Be sure that the oil ring doesn't bend over.

With the motor together, and no crankcase oil rotate it 50 times. Then fill with oil and check all fluid levels

Do not start the bike until you intend to ride it. Start it up, let it warm up good, go ride it hard with engine breaking, this will ensure the ring seal.

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dry rebuild simply means don't put any oil at all on the rings and piston when installing...only a dab on the wrist pin like 250f rider stated

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It might be a good idea to pull off your sparkplug wire when rotating the motor, or at least hold the kill switch. You wouldn't want to have your freshly built engine start up with no oil in it.

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you slowly rotate it 50 times without oil to help the rings initially seat to the cylinder. (The bike won't start because of how slow you are rotating it, but hold the kill switch just in case.) As soon as you start the bike the oil mister hits the piston -- so this does not hurt anything. --- do not start the bike until you intend to ride it - then you go ride it hard with engine breaking...

You can also break in the bike on the road if you like. Warm it up - go run it hard through all of the gears (if space provides try and get to or almost to the limiter in 5th) then engine break down, repeat a few times. Then you are set.

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thanks a lot man, it seems like you know your stuff.

ill sure come to you a few more times to ask you some stuff probably cause im doing a full engine rebuild on one of my crf250s.

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