Break in new cylinder

[Irongamer727]

I'm getting more acquainted with the brake in procedures. I've always thought you couldn't be too careful running an engine in. Obviously I was wrong. The fact that idling can glaze the bore scares me! I mean you need a good 20 minutes to bled the cooling system of air.
Guess a moderate run in with a bit of variation of revs is preferable.

[Calum]

I always thought it was giving it too much chst before thr rings have bedded in causes glazing.

Either way, get it runing and put some miles intonit before hammeringnit. That's my advice. Two strokes don't last forever so it's a moot point if it lasts +-1k miles. The main thing is getting that fueling spot on.

[declan]

@calum 20 minutes to bleed the cooling it only took mine a few seconds

[oldman]

You should warm the engine thoroughly to make sure thermostat opens and gives full flow to water passages, otherwise pockets of air could remain

[Irongamer727]

@declan after 20 minutes there were still air left. But at that point I felt satisfied.

[Calum]

I don't think I've really actively bled the coolant system on any of my builds. Fire her up rad cap off, just top it up. Quick blip round the block top her up jobs a goodun

[Irongamer727]

@calum works for some

[declan]

@calum well I took my cap off started the bike and after a little bit the coolant expanded and started overflowing so it only took me a few seconds maybe 30s tops

[Irongamer727]

@declan ideally you want to warm it up to operating temperature with cap off. That way you know there won't be excessive amounts of air once you're out riding. My radiator started pissing out coolant through the overflow hose due to improper bleeding.

[declan]

@irongamer727 so I just let it spill out?im pretty sure I managed to get all the air out of mine

[Irongamer727]

@declan lucky you! I'm only telling you what I experienced with my bike.

[Irongamer727]

@calum you think it's possible to glaze the bore of a plated cylinder? (Nikasil)

[Calum]

@irongamer727 Yes

[Irongamer727]

@calum got dammit. I just want to start the bike, listen to it, set the idle and bleed the coolant. I have had it running for roughly 20 minutes on idle before so now I'm thinking of waiting until the snow disappears and then start braking it in.

[Calum]

@irongamer727 Don't worry so much about it. Just go out and ride it. It's not going to cause it any harm.

Glazing the bore is going to happen if you literally build a fresh engine, then take the engine to the max non stop for the next thousand miles. You're talking about shortening the life of a two stroke whose top end should be rebuilt every 10k anyhow. So it really makes no odds. Stop worry about it so much.

[Irongamer727]

In theory, would a new cylinder and piston be run in after non stop 500 km riding. (We're assuming the engine runs rich with plenty of oil and is ridden carefully) or would it need some cooling down at times?

[declan]

@irongamer727 providing you have done your heat cycles and that the ride in question isn’t it’s first ride then I see no reason why you shouldn’t be able to without letting it cool down

[Irongamer727]

@declan I'm meaning the first ride. No heat cycles involved

[declan]

@irongamer727 then no I wouldn’t advise it

[Jens Eskildsen]

I've never seen anything scientific about heat cycling after a bore job, so I wouldnt worry about that one.