Break in new cylinder



  • How would you guys do? Obviously have to start it, let it idle to bleed the rad. But then what? Just a careful 500 km? Some say you should start it, let it idle to operating temp and then shut it off, repeat up to three times. To expose it to the heat cycles. (I don't mind spending a bit of extra time breaking it it).



  • You'll always get differing answers depending on who you ask.

    I guess that means there really is no proven way to break in new engines.

    What we do know is that you need to take it gentle to bed the rings in to the cylinder wall, to avoid glazing.

    How long it takes for the rings to have bedded in I guess is the arguable part.

    I think first off and foremost you would want to do a 100km just taking it easy to ensure you have assembled it all together correctly.

    From there, varying revs but no load for the next 100km.

    At this point you've proven that the engine is assembled, the rings should have had time to bed in properly, which means it is technically run in. Give it another 100km before I would be satisfied all is well with the world, but that doesn't mean you can't thrash it. Just within reason.



  • @calum how about letting it idle to operating temp, then very carefully riding 500 km in one or two days? I personally have always let my bike warm up idling before each ride, something I will probably remain doing. Overkill? Perhaps, but it shouldn't cause any damage right?



  • @irongamer727 So risk of riding like your nan on a two stroke is fouling the plugs, clogging up the exhaust, powervalve and all of that.

    Unfortunately, two strokes are filthy machines. They burn the oil that they need. It gets everywhere and they absolutely must be opened up fully more often than not. It's not a fourstroke, forget reliability, these are high revving oily machines. As such, they need to be opened up.

    The dilemma then, you're trying to break in a new cylinder and thus do not want to open her up...

    Sorry, but there comes a point where it's actually worse for the machine driving it softly. You will have to open it up to clear the dirt.

    Breaking in engines isn't something I can answer. I have far too little experience to tell you what for. You will see people say three heat cycles is enough. YOu will see others say heat cycles and then a full chat blast up the road. Something about forcing the rings outwards against the bore.

    Ultimately, if you really want a definitive answer, you'll have to look past this forum as it's simply a minefield out there. Experience is all I have to go on. And I just do what I described about. You may want to do your idea and it works out perfectly, but as you begin to tune two strokes, you'll realise they can't be ridden softly for extended periods of time.



  • @calum I understand, however riding it 500km softly will definitely not clogg it up. It is routine maintenance to clean the pv and such. I might do it a bit more often then. Do you simply ride away with the engine cold and slowly increase revs? Might have to consider doing that as well.



  • I always warm bike up first, rebuilt or not. Ride sensibly at first after rebuild, as Calum says, to make sure all is well before stressing the engine. Personally increase demand as the miles rise and then ride "enthusiastically" , gotta reach that power band! Imho hot engines stay cleaner than Luke warm ones.



  • @irongamer727 It's not just the powervalve though mate, I'm talking about the piston rings, the piston crown, combustion chamber, exhaust port and even the exhaust. All of that gets clogged with carbon due to the excessive oil not being burnt through low riding.

    I would always warm my bike up before riding, without a doubt. Especially when using forged components.



  • Add a bit of extra oil, ride gently for the first tank.
    After that, ride the bike normally, without redlining it for the following tank.
    Done.

    You should be ablo to just about flog the bike after its warmed up, but the above helps me sleep at night



  • @calum what's you standard procedure? Idling for a couple of minutes?



  • @irongamer727 Refer you to my first post, but Jens method sounds legit to me.



  • @calum oh sorry I didn't mean during the break in. Let's say you take your Dt out for a ride. How do you warm it up? Idling? Calm riding?



  • @irongamer727 What I did, was leave my house. Start the bike up, always needed choke, let it idle. Walk back to my gear, put my helmet on and gloves on, by which time the idle was drastically dying and I needed the choke of. Ride off. I never rode it hard until it was up to temperature, but the RE's don't have a temperature gauge.

    Put it this way, these are commuter bikes, in stock form they are designed to be ragged from cold, excuse the expression.
    They are meant for jump up idiots, for which I wasn't one, to go on and obliterate. They were designed to do countless miles with minimal maintenance.



  • @calum pretty much sounds like my every day routine



  • @irongamer727 I always warm mine to a warm radiator then I start revving to clear the smoke then by the time that’s done and I’ve pushed it up the garden it’s good to ride just put your hand on the rad and if it’s like warm you can start revving to clear it out it avoids fould plugs, as for break in there’s a lot of bull sorrounding it with my bikes I always do heat cycles then I take it easy not for a specified time or mileage usually two rides then I start riding normally but no redlining and then it’s pretty much when you feel comfortable riding it properly it’s all down to you but just remember hard break ins are bollocks and so are soft break ins the answer is in the middle you don’t want to lug the engine but you also don’t want to create excessive heat and wears during the break in, that said on my project bike I just finished on it’s first ride I rode it normally up to redline no issues it’s only a 70 so not a beast so you kind of have to ride it like that I only paid 50 for the barrel and head piston full endgame gaskets and silicone sealant so it’s not exactly an expensive thing to have go wrong I wouldn’t ride a dt or any other bike like that though



  • @declan Ye, well I can monitor the temperature exactly since i have fitted a gauge. (Best choice I have ever made) so overheating shouldn't be a problem. Just extremely frighten something bad will happens during the break in.
    Like it won't get enough oil.
    Running to lean etc.
    Even though I have almost everything covered and fixed.



  • @irongamer727 By the time you notice any change in temperature, the damage is going to already be done.

    Just ensure that the oil pump is bled and pumping oil. Since it is not a closed system, I dont' bother bleeding it, I just add oil into the petrol and run through a tank rich on oil



  • @calum I have not messed with the hoses to I should be good. Wounder if I should turn up the pump just ever so slightly.



  • @irongamer727 I did on the stock barrel just cause.



  • @calum yeah I did the same if you want I can link you Calum’s video so you can run the same settings as us two?



  • @Irongamer727 https://youtu.be/WwFUzgr2xnA there it helped me a lot