Is it Absolutely Necessary to Break in my new Engine?

Discussion in 'General Questions' started by Gan, Aug 13, 2016.

  1. Gan

    Gan New Member

    In a previous post, I mentioned that I would be purchasing a Predator 212cc engine to motorized a tricycle with. I have seen many people take the engine out of the box, add oil and gasoline, slap it on their go kart or bike and run it.
    On the flip-side, I have seen many people break in the engine for 3 hours before they start using it.
    I live in a densely populated area and I'm confident that my neighbors don't want 3 hours of me running my engine next to them.

    Is it absolutely necessary to break in the engine? Would it be harmful to put the engine directly on the tricycle?

    Any advice is greatly appreciated.

  2. crassius

    crassius Well-Known Member

    depends on how it left the factory - might have been spun in before shipping, might not
  3. CrazyDan

    CrazyDan Member

    Most people break in their engines under load. I've seen it mentioned that breaking in under no load can cause the rings to not seat right and can glaze the cylinder walls. Let the engine warm up for like 10 minutes then take it out and cruise for like a half hour at low rpms, occassionally opening the throttle up for like a half second. Some will do an oil change right after this initial run to empty out any metal shavings that will have been grinded away. Then let it warm back up and take it out for another spin for at least an hour, slowly building up rpms. After around a half hour or more, start doing like 5-10 seconds of wide open throttle, but try to keep your cruising to around 70% throttle. Maybe try to find a little hill to tackle, but don't take on anything too big yet. After this longer ride do another oil change and enjoy your broken in engine. What you are doing with this is forcing the rings to press against the cylinders and seat correctly. This all can't be done idling or reving with the wheels off the ground, you need the engine under load.
    Dustmonkey likes this.
  4. Frankenstein

    Frankenstein Active Member

    I believe solely in running it like hell to break it in, now it might not apply to 2 strokes so well, but 4 strokes definitely. Running it hard and hot gets the lube in all the right places (it is designed to do just that, more oil be with more rpms, add that mystery oil additive to make sure it just gets everywhere) and also gets the rings seated nicely (its forced air cooled, don't worry about overheating a 4 stroke with forced air except for special circumstances) by running it hard to get them driven in well, you only get one chance to do this, and if you plan on using it hard then seat the rings where they will be used, not almost used.

    The engine is a pretty formidable foe to taking on ideal characteristics when you talk 4 stroke vs 2, the 2 stroke is firing twice as often with generally more energy in a smaller box, with less moving parts and to top it off it burns it's oil instead of using it from a set supply of oil that increases it's spread with engine speed, the 2 stroke will use the same relative amount each time in the combustion chamber which changes how much is being applied to the cylinder relative to heat build up, 4's just keep spitting oil in there and if it's running faster just means less has left the area it's needed, and the design pretty much ensures it gets the oil it needs regardless of rpms (up to a point of course)

    I might not tear into the 4 stroke ever, BUT I have broken them in, and maintained them with very astounding results by my calculations (I wouldn't be proud if I was killing my engines faster, I'd be worried and looking for professional help) and wound up having 4 strokes that not only have better gas usage but also have continuously comparable power in comparison to others who's power seems to continually diminish year after year.

    I find a few sites while trying to back up my learnings, but this one is by far the best, I don't ever open my own engines but the mechanics also don't think the odometer/hour readings match the motor either, so I'll call it a fair bet I'm doing it right.
  5. Frankenstein

    Frankenstein Active Member

    I'll also add that one of the highpoints of me working on building a 4 stroke motorized bike in the winter (this state seems to have varying versions of winter, averaging 3 months) is I've got that many months at least to piece together a bike, then when spring and it's wonderful weather (again another shitshot in this particular area, year round actually) come about I'll be able to break in my bikes motor nicely before I plan to give it to the wifey, at least in PA you find plenty of open room between major cities, and if you let the local pd know ahead of time that you'll be breaking the speed limit for the sake of engine lifespans they tend to appreciate it and make sure you aren't bothered too much, if a rookie didn't hear the news from his CO then he ultimately hears it from you and rather than ending up looking stupid he let's it go, especially if the bike is cool looking in general and close enough to legal for his taste at the moment.

    Yeah anyways, 4 strokes have been the most popular type of motor because they are robust and well let's admit it, who hadn't floored it in a new vehicle (or nearly broke the handlebars off during the Uh... Testing phase... If the dealer didn't do that already) and have the ability to completely out perform 2 strokes overall when set up properly (aka: not by the manual, which is outdated, particularly because the manufacturers got so good at building motors that they don't need an easy break in, and the simple properties that make up the parts that actually need breaking in are in need of harsher environments to get them where they should be for best performance and longevity.

    I think I should place a disclaimer right here, where I state my beliefs are based completely on my own experiences and trial and error dealings. Which means no part of my posts should be considered factual, and it is probably just as likely that the manufacturer knows better how to run an engine than to build one at minimal costs and make a profit versus instructing you how to keep an engine running as long as possible so you don't need to buy more cheap engines from them. Yeah, that should be a good enough disclaimer.
  6. libranskeptic

    libranskeptic Member

    Use common sense & normal good practice w/ extra tlc. Dont ride dead cold, ride like a pussy 1st 5 minutes if u can.

    Residual filings are inevitable. Do initially change 4 stroke oil 2/3 times when hot, until no filings glint in sun in used oil. give motor a good oil flush.

    if u were keen u could initially remove plugs; spin it with a drill somehow, & squirt scads of oil on cylinder walls while spinning.
    Dustmonkey likes this.
  7. JunkyardDog

    JunkyardDog Active Member

    Depending on the engine, there are several tricks to breaking it in properly. Most modern engines are built to such close tolerances that an actual break in is not necessary. But you still have to seat the rings. To do that you need to give it several full throttle bursts under load. You have to build up pressure in the combustion chamber to seat the rings. This applies to pretty much any engine. Start it up, warm it up, then ride a couple of miles slowly to make sure things are ok. Then give it about 3 full throttle bursts, shut it down and let it cool off, then repeat that sequence 3 or 4 times. Do not let it overheat. A brand new piston is soft and easily damaged. It gets a lot harder and stronger after several heat/cool cycles. For an American or Japanese engine, that's about it. For a Chinese or Indian made engine, you start off the same way, but once you have seated the rings, you still have to ride them carefully for a long time, as they are not built nearly as well. My Indian made Genuine Stella Scooter had a break in period of 1200 miles. It took me over a month to break it in, riding it 20-30 miles at the time, varying the throttle, letting it cool off for half an hour or so, then doing it over again, gradually increasing the distance ridden as the miles piled up. My Indian made Royal Enfield motorcycle was the same way. I don't know where your engine was made, but if it is Indian or Chinese, it will need a long break in. But it will still need to have the rings seated to begin with. Once the cylinder walls glaze, it's to late to seat the rings. You have to hone the cylinder, replace the rings, and start over again.
  8. butre

    butre Well-Known Member

    the best way to break in an engine is heavy load, full throttle, low rpms. if you've got a big long steep grade nearby, go WFO up it
    Frankfort MB's likes this.
  9. JunkyardDog

    JunkyardDog Active Member

    Wrong. Full throttle and low rpms = lugging the engine, the worst possible thing you can do to any engine, broken in or not. Lugging an engine will pound the bearings to pieces very quickly. It does need full throttle, but only in short bursts, to seat the rings. After that, ride it normally for the next couple hundred miles, varying the throttle and giving it a lot of breaks to prevent overheating. The problem with those China engines is that no matter how you break them in, they have a max lifespan of 1500-2000 miles. A stock 2 stroke 49cc Puch moped engine OTOH has a lifespan of over 50,000 miles. Quite a difference, and all because of quality.
  10. Frankfort MB's

    Frankfort MB's Well-Known Member

    The OP is buying a 212cc predator..... So your wrong
  11. butre

    butre Well-Known Member

    not like about to stall out low, but not revving the rings off.
  12. jaguar

    jaguar Well-Known Member

    Let me ask a question. If all the engines come with excessive ring end gap (it was 3 times normal on mine) then how important is it to try to get the rings to break-in and match the cylinder perfectly? I'm not advocating running it full speed for a long period of time right out of the box but this engine is too sloppy to be treated meticulously in some areas such as break in.
    Frankfort MB's likes this.
  13. Tony01

    Tony01 New Member

    Motoman method. MAKE SURE ENGINE IS WARMED UP before ANY break in or riding!
  14. oliverw123

    oliverw123 New Member

    I agree with your break in method. What I don't really agree with is the max lifespan mentioned. I completely stripped my 49cc china engine for a chekup and it is in excellent condition having endured 5 years of long distance and hard riding. I have done 21 000kms with this one. I've just replaced the piston/rings and barrel because I damaged them whilst reassembling. I had the piston orientated the wrong way and the ring ends clipped the intake port whilst trying to insert the piston. I got too heavy handed with a block of wood.

    In the process of breaking it in again for maybe another 20 000kms of riding?? who knows.