How To: Break in an engine

[700xxmaniac]

Originally posted by stumpjumper_09
When I bought my sportsman 700 I flogged the crap out if it from day one........ big mistake!!! before it had 500 miles on it i was tearing it down, deglazing and installing new rings. I'm gonna try to break in the Brute a little more gently in hopes that it will last me a long time.

it wasnt the break in.. the polaris engines are **** i only had 50 hours on mine (with the right break in) and it needed new piston and cam

[wingnut548]

I have been running drag bikes and cars for years.Some of the top engine builders in the world have told us on our drag motors to start them up and run them about 2000 - 3000 rpm for about 20 minutes and then shut it down recheck all fluids and go at it. Now our drag car runs about 900 horse power with 500 additional horse on three stages of nitrous. I have about 120 1/4 mile passes on our car and when we tore it down it all looked brand new inside. Now I have broke in both of my banshees in this manner and have never had a failure in an engine with probably around 150 builds over the years. The one thing that really make or breaks the build is attention payed to tolerances and always use quality fluids (like royal purple oils etc.) during the life of the engine. I have also seen alot of engine failures fail during the break-in due to people not properly setting up the jets and carbs to the right mixture ratios. They have an engine failure, rebuild and put it right back the way it was and have another failure becouse they did not correct the initial problem that caused the failure to begin with. Just my two cents on the subject. Not that anyone is right or wrong there are just many ways of doing things.

[flyjum]

Seizing is from the piston ring end gap being to small and the rings pushing against the other end of the ring making it push outward.

It can also be from a forged piston not being sized right.(too tight)

Piston slap in many GM v8's is the reverse of this. (to loose making it slap when its cold on startup)

On atv and race engines you need to run LARGE piston ring end gaps due to them expanding so much.( your gap on a wiseco should be the second or first largest ring end gap on the chart it should say turbo/race or turbo/nitrous ring gaps.)

Best way to break in an engine is to vary load and rpm.

That means 5% to 100% throttle usage and 2000 rpm to redline rpm usage normaly in higher gears (3-5 on atv 2-4 on car).

This will seat the rings with out glazing the walls. On all new cars they break the engines in this way before you even get the car.

[Thumpin440ex]

Kinda of old but thread, I got a good laugh out of the thread.. True story. Back when I first bought my bike NEW in 2000, my buddy had the same bike.. He did the baby break in method. I was just a bit harder on my bike, but still changed the oil and checked the valves after the first tank of fuel. My 400 would walk past his on the top end all day long.. So we thought it could be the rider. I hopped on his bike, he hopped on mine, same thing. Like stated earlier, there is many diff ways people break there engines in... I have done cam swaps in performance engines( cars, boats) where it is right in the guide to break a cam in @ 3-4k for the first 20 min.. Key to the engine living is to change the oils, use a good break in oil, keep changing the engine R's during this.. Run it hard, just not to hard off the get.. It is true, if it is going to take a $hit it is going to do it...


TO FLYJUM

Another reason for piston slap in the lsx engines is mostly due to the fact of the piston design.. They have really short skirts on the pistons, have what is called piston rock at the bottom of the stroke..

John

[265 sleeper]

i never run my bike more than 5-10 min before the 3rd heat cycle then after that i dont go no more than 10-20 mins but always letting my bike cool in between rides never holding wot in till ive let it cool 5-8 times never had a problem from banshees, blasters ,and 250rs as well as 4 polks that ive built and owned . my first blaster i built still running after 2 years of me riding it hard and i sold it to a kid that i know didnt take care of it he still riding it to this day and is trying to sell it has not goin through top end still holding psi at 155 after 5 years of use

[Honda4life05]

i just rebulit my honda 450r 15 hrs. ago and broke it in easily with heat cycles. THAT WAS THE WRONG MOVE! it is now in the shop getting new rings put on. It had such low compression that it wouldn't run right at high rpm. this time i'm going to brake it in just like i ride it. HARD.

[firefighterjosh]

Originally posted by Honda4life05
i just rebulit my honda 450r 15 hrs. ago and broke it in easily with heat cycles. THAT WAS THE WRONG MOVE! it is now in the shop getting new rings put on. It had such low compression that it wouldn't run right at high rpm. this time i'm going to brake it in just like i ride it. HARD.

How did you do it?

You need to let the engine warm up, and put a load on it for the rings to break in properly. Takes about 3 cycles.

On race engine we normally put it on a dyno and rev the engine to about 3k and put a load on the engine. Let it cool down over night and do the same in the morning.