How do you break in your motors?

Well we took a thread off track on this subject, and it got a little argumentative in the fact that some think this is a cut and dry right and wrong thing.

Before we go into it more, let's just post the methods each of us use individually. Rather than argue as to what is wrong or right, I'm really just looking to see who does what method and there results.

I use the ride it like you're planning to run it. So, i warm it up on first startup, for about 5 minutes i let the engine get to temp. Then i get on and go through all the gears making sure to decellerate when slowing down through all the gears. AFter about 5 minutes of that, i open it up and ride it like normal. I've only done 3 pistons and 2 full rebuilds so i don't have hundreds of motors that i've used this method on. So far it has worked fine for me.

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Originally Posted by 2001400exrida

Well we took a thread off track on this subject, and it got a little argumentative in the fact that some think this is a cut and dry right and wrong thing.

Before we go into it more, let's just post the methods each of us use individually. Rather than argue as to what is wrong or right, I'm really just looking to see who does what method and there results.

I use the ride it like you're planning to run it. So, i warm it up on first startup, for about 5 minutes i let the engine get to temp. Then i get on and go through all the gears making sure to decellerate when slowing down through all the gears. AFter about 5 minutes of that, i open it up and ride it like normal. I've only done 3 pistons and 2 full rebuilds so i don't have hundreds of motors that i've used this method on. So far it has worked fine for me.

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I wouldnt say Ive done hundreds but Im well into the double digits of full motor builds and use almost your same method. Idle just enough to make sure everything is tight. A steady cruise from the garage to the back field doing some engine braking along the way and once i get to the field its WFO. A few minutes of WFO and back to the garage for an oil change. After that im ready to ride. Now ive also bought several brand new quads off the showroom floor. When they come off the truck they are fired up and WFO from the time they fire basically. If its gonna happen under Honda warranty i want it to happen ASAP.... A story behind my break in method. In 2002 I bought a brand new 400EX. it stayed stock its whole life, It was broke in WFO as soon as it hit the dirt at my parents place. A good friend of mine bought a new one about the same time. It also stayed stock most its life. With 2 guys close in weight and riding skills on each quad. My 400EX would eat the pants off my buddies every time in a drag race. He broke his in putting around the yard for about 5 hours. As far as ppl saying you cause premature wear breaking one in that way. My 450's dont get to the point of NEEDING rebuilt anyways. They are rebuilt for preventive maintenance based on how many hours and what kind of riding they have been thru......and that ol 2002 400EX....well its still running, as far as i know its only had the rocker arm caps off of it. I sold it at 2 years old and still see the current owner every now and then

I've been told to run it on a full tank of gas under half throttle or around half throttle through all of the gears. Then after that, change the oil and "ride er like ya stole it."

blacknblue, your story matches what I have found in my limited experience with motor builds but also what I have read. Running them WFO after a 5-10 minute warm-up period seems to make the motors run stronger. Maybe it will slightly reduce the longevity (maybe) but as you said most everyone on this forum is looking for performance over longevity anyway.

When I was younger I rebuilt the bottom and top end on a bored and stroked, fully built big valve 500cc 350X motor. I was attempting to break it in slowly but it developed an air leak on the intake and it would run lean and when this happened it would rev up to the moon before I could grab the clutch, brakes, and kill switch. Of course it took going through this several times before I figured out what the problem was and it scared the **** out of me that I was accidentally screaming a brand new motor that I had just spent thousands of dollars on. Well after I got the air leak fixed that motor pulled VERY hard and is the strongest quads I have ever ridden. A year or two later I cracked a case on that motor and bought another low hour 500cc 350X motor and even though it had the exact same bore, same stroke, same cam, same pipe, bigger valves and even a better FCR carb it never pulled as hard as the one that was literally broken in at WFO. I bought it used so didn't break it in myself but I did tear the head off and inspect it before I ran it and it was indeed a very low hour bored and stroked motor but didn't run as strong as my other one.

good info guys.