Anyone ever seize a 4 stroke with new piston?

Im currently putting a new piston and rings in my yzf 450 and i know break in techniques can be debated for hours but ive heard many stories of people absolutely thrashing the life out of a new piston and then saying it turned it into the best biike they have ever had. Every piston ive run in ive taken the slowly slowly 1/4 throttle , 1/2 throttle approach but this time im thinking of just taking it to the track and letting it rip.

So basically my question is has anyone ever actually seized there bike from doing an improper break in?

its not going to seize. The big debate is how to wear the rings perfectly not weather its going to seize or not.

I heard let it warm up take for a short ride enough to get to operating temp staying below 50% throttle change the oil ......... then ride it like you intend to ride it the rest of its life. change the oil after the next few rides.

Cranks and gearboxes are more of a concern on new bikes.

As mentioned above , bedding in the rings is essential. If the piston is sized correctly then small initial break in is all that is required.

DO NOT use top of the line fully synth oil for break in, a quality semi or mineral is best initially, then drain and replace with your usual type.

DO NOT use top of the line fully synth oil for break in, a quality semi or mineral is best initially, then drain and replace with your usual type.

One of the oldest automotive myths left alive (along with several regarding high octane gas). The only reason a non-synthetic is better is because it's cheaper to change it right away. Otherwise, there is no reason not to use the best oil you can in the engine at all times, including, and perhaps especially, when breaking in. Within the first 30 seconds of run time, there will be no oil on either compression ring, anyway.

One of the oldest automotive myths left alive (along with several regarding high octane gas). The only reason a non-synthetic is better is because it's cheaper to change it right away. Otherwise, there is no reason not to use the best oil you can in the engine at all times, including, and perhaps especially, when breaking in. Within the first 30 seconds of run time, there will be no oil on either compression ring, anyway.

there should always be assembly lube in the cylinder, the rings pick up off the cylinder,this protects it from the first 30 - 1 min, very true about the mineral oil, having built a 500 hp small block ford we used cheap 10 30 in the first 3 oil changes given they stayed in the motor for less than 3 hrs run time, also used break in oil additive but I would be careful ( not use ) on a bike as the clutch is a wet setup.

One way to get it to seize is not to hone the worn cylinder, the rings may not seat and you get alot of blow by and then seizure is a posibilitiy. I think that happened to me.

I'd just go ride the thing.

One of the oldest automotive myths left alive (along with several regarding high octane gas). The only reason a non-synthetic is better is because it's cheaper to change it right away. Otherwise, there is no reason not to use the best oil you can in the engine at all times, including, and perhaps especially, when breaking in. Within the first 30 seconds of run time, there will be no oil on either compression ring, anyway.

Well I have to disagree on this statement based on Redline's statement. Basically says NOT to use they're oil during break in unless you are putting the motor under a heavy load right away. Probably geared more towards a daily driven street car. The group V Polyolester base oil is a different animal than any other oil.

Q: Can I break-in my engine on Red Line motor oil?

For peformance engines, we recommend using conventional 10w30 motor oil to ensure proper piston ring seating. We recommend using this oil in combonation with our Engine Oil Break In Additive, which features the antiwear chemicals necessary to protect valve train components like camshafts, rollers, and tappets. Though most conventional oils are missing the important antiwear components that you find in Red Line's synthetic motor oils, the conventional oil is not as slick as Red Line and will allow the piston rings to seat more quickly. If you allow 1500 to 2000 miles in a street engine or 20 to 30 minutes on the dyno at low rpm, the rings will have had sufficient time to seat and the high initial break-in wear will have occurred. For new road cars, always follow the manufacturer recommendations and initial oil change recommendations for break-in.

From website

Edited by Gunner354

Many new cars come with synthetic oil from the factory these days.

Don't care what Redline's site says, or for that matter, really what anyone has to say about the matter, and the question of whether it's an ester oil or not has even less bearing on the subject than whether it was pumped out of the ground or built in a lab. The idea that synthetics will prevent modern compression rings, or oil rings, either, from seating is patently ridiculous. I would be afraid to estimate how many engines I've built over the last 45+ years, but it's multiple 100's, I assure you. Of those, not one failed to seat the rings by any measurable indication. All of them were built using the same oil that either I or the shop I worked in at the time recommended for normal daily operation, and from 1982 onward, this has always meant a top tier synthetic.

Chevrolet, Cadillac, Mercedes Benz, and Porsche, to name only four, build top of the line performance cars in which the engines are factory filled with synthetics from day one, and most of those will void the warranty on the car if any oil other than that is used.

The idea turns on the concept that synthetic oil lubricates better, or "it's slipperier" than petroleum oil. This, they say keeps the rings from wearing to match the cylinder. Not true. Synthetics are more durable, and will maintain their lubricity under more extreme conditions, but the oil for a wet clutch bike is only allowed to be as "slippery" as the JASO T90 standard associated with MA rated oils, anyway.

Do whatever you like. Believe whatever you want. Won't change anything. There is no reason besides price not to use a synthetic for break in.

There is, however, a very good reason to avoid "babying" your new top end. It should be warmed up a bit more gently than the typical 17 year-old normally does with a dirt bike, but following that, it should be subjected to short, but significant bursts of load to create enough pressure to ensure seating. After the first 15 minutes the loads should be longer and harder, approaching the kinds of riding you'd normally do, and after the first 25 minutes, it should get a reasonably hard run or two.

One of the oldest automotive myths left alive (along with several regarding high octane gas). The only reason a non-synthetic is better is because it's cheaper to change it right away. Otherwise, there is no reason not to use the best oil you can in the engine at all times, including, and perhaps especially, when breaking in. Within the first 30 seconds of run time, there will be no oil on either compression ring, anyway.

Your probably correct Gray, after years of building some very fast race engines I will just stick to what I know and has worked for me.

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