Break in period

[askmrjesus]

Originally Posted by Sean

This is what my piston looked like after 2000 miles with a hard breakin:

Sorry, but you can't automatically chalk that up to a "hard" break in. Any number of things could have caused that damage.

My DR650 thumper was broken in to spec, and the fucker hand-grenaded the bottom end at 16K miles, (I'm pretty sure the shift fork was the culprit). So, what does that prove? Nothing. If shit's gonna break, then shit's gonna break.

I wouldn't rev the ever loving piss out of a brand new engine, but after the first oil change (100 miles), all bets are off.

JC

[Homeslice]

The best method for this to occur is to run the engine right up to the manufacturers listed "red line", BUT with the LEAST LOAD POSSIBLE (remember load = heat and NEW pistons DO NOT like excessive heat!).
How do you do this? Well, with any vehicle that has a gearbox, it's real easy. When the bike/vehicle is brand new, you begin a series of "low load", HIGH RPM runs (right up to red line), but ONLY in FIRST GEAR. This gives the VERY necessary "high RPM wear-in" for the pistons and max "gas pressure" on the rings to press them into the cylinder wall so they can seat WITHOUT high load/heat.

Not understanding the logic here.....Why would a first-gear blast produce "less load" than, say, a second-gear blast? Just because it's shorter? But the accelerative forces are higher in 1st gear, so you would think that would produce more load.

[Tmall]

I've been drinking, so bare with me slice.

The amount of power produced doesn't change. You can manipulate that with gearing, but the forces being applied to the gears should always be the same.

Power out equals power in. First law of thermo.

[Tmall]

Since I can't edit on my phone..

I can however see the forces acting for a longer duration on the piston at higher revs since the same amount of force is being applied over a longer distance/time.

[Homeslice]

Power produced would be the same I agree, but the G-forces are higher in 1st.... after all it is easier to loop a bike in 1st than 2nd or 3rd. So I would think it would put more load on the bearings. But I don't know shit about physics.

[racedoll]

Damn this thread is long. I forgot I posted it on Thursday/Friday before going away.

Originally Posted by fasternyou929

I followed the break-in period for both my new bikes. You'll hear all kinds of arguments from both sides about which is better. In the end, I decided the people that designed and built it know better than anyone else and I've never had any problems.

That's not to say if I took it to the track right away I would have had problems.

You might be better off asking what tires are best for street riding.

I figured this would be a questionable subject but I thought I'd take my chances on the answers.

Originally Posted by OneSickPsycho

I tried... Really I did... It was just too boring!!!!!!!!!!!!!!

I know what you mean. I rode mine per break-in home from the dealer. Hubby asked why I was going so slow (not even the speed limit of 55mph). I told him I was following break-in... so after that he told me to at least go the speed limit.

Originally Posted by fasternyou929

Not looking to recreate an old debate, but if beating the piss out of a new motor were the way to go, why would manufacturers have a break-in period versus saying "here's your new bike, go ride it"?

That is kind of my thought, but at the same time I couldn't not do the speed limit for 1000 miles or whatever break-in suggested.

Originally Posted by askmrjesus

If shit's gonna break, then shit's gonna break.
JC

[Tmall]

I meant at higher gears .

[RedRider2k2]

Originally Posted by Homeslice

Not understanding the logic here.....Why would a first-gear blast produce "less load" than, say, a second-gear blast? Just because it's shorter? But the accelerative forces are higher in 1st gear, so you would think that would produce more load.

Where did you quote that from? I'm not sure I agree with it but anyway...

The reason there is less load on the engine in 1st is because the gear reduction in 1st gear makes it easier to drive the bike forward and reach redline. In higher gears the ratio is not so much in your favor and it takes more work. It's pretty much the same reason that if you have a worn clutch, it's most likely to slip in high gear.

[fasternyou929]

One question for everyone that likes to hit red-line before the first oil change: are you not worried about metal shavings cycling through the engine with the oil? Isn't that one of the main reasons for low RPM's at first, to cycle the oil at a slower rate, increasing the chances metal will stay at the bottom of the oil pan?

Originally Posted by Homeslice

Not understanding the logic here.....Why would a first-gear blast produce "less load" than, say, a second-gear blast? Just because it's shorter? But the accelerative forces are higher in 1st gear, so you would think that would produce more load.

Simplest way to understand this - assuming you've ridden a mountain bike or multi-speed bike. Put your pedal bike in 1st gear and sprint to your maximum speed. You should reach your maximum speed quickly and with little effort.

Now do it again in a middle gear... it'll take a lot more effort to get to that max speed (load to an engine), not just time.

If you're a glutton for punishment, put it in its top gear now (10th, 18th, 24th, whatever) and repeat. Have water handy and be ready for your quads to scream at you.

[Kerry_129]

For a given amount of air & fuel introduced (throttle), a motor will produce the same output & the internals "see" the same thermal & mechanical stresses, regardless of which gear it's in - it's only the reaction (acceleration) which varies. (edit: assuming it's not 'free' revving)

So which oil should I use for break-in?....