Break In What's the best way to break in an engine?

cmb271

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Jan 5, 2015
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Okay, I'm in the planning process of building another motorized bike but doing it properly, I didn't do enough research in the beginning and I paid for it. My original bike I feel I didn't break it in properly and this bike I'm planning to build will be my daily commuting machine, it has to get me beyond 20 miles : something my other bike was to unable to do without breaking down. Which way is the proper way to break in your bike?

Riding it for a set period of time at a low speed or prop up the frame and allow the rear tire to spin freely at a limited throttle and set time (with a fan at the front to keep the engine cool)

If you have any more suggestions or tips, feel free to share them.
 


Frankfort MB's

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Apr 3, 2016
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I've always had good luck out of giving all my motors absolute hell lol yeah yeah I know

It lets the rings seat properly, gets all gunk out of the way
Just don't rev it too much that's not good on the bearings, give it heavy loads with low RPMs for about 2 gas tanks then you should be broken in
 

cmb271

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Jan 5, 2015
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What happened to your other bike?
I first had a two stroke bike and I snapped the bolt that mounts it to frame, the engine wasn't repairable. The second one was a 4 stroke but the bolt holding the 10 tooth sprocket came loose and I lost the key, (I also think I may of stripped the screws holding the transmission on the engine). The bike is beat to crap due to lack luster maintenance and poor planning so I'm just going to buy a new bike that would handle the load better and ensure I do it properly so I don't have any breakdown issues.
 

Frankfort MB's

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The motor mounts are reparable, just tap the hole to a larger size and that has nothing to do with breaking in the engine. It happened because you overtightened the stud. Doesn't take much to overtighten these cheap Chinese studs

Idk anything about 4 strokes, I'm not smart enough for them:)
 

bakaneko

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Nov 16, 2015
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A 4 stroke might have the reliability you require for your commute. I am at about 800 miles and not a single problem with it. I went 35-40 miles on one trip and no engine troubles but my gas line kept coming loose and my rear gas tank almost fell off, LOL. Those goof ups were my fault and engine performed superbly. I had a 2-stroke and the issue with that was you never know when something is going to %@$^ up, LOL. If you are really handy with tools than a 2-stroke has better power.

But, for folks that just want to enjoy riding more than building I recommend going with a 4-stroke. I broke in my 4-stroke by varying the RPMs for a couple tanks of gas and adjusting the mixture screw. Some say really gun it and others say take it easy; who knows. The mounting plate of the 4-stroke motors seem stronger than the flimsy M6 bolts on the 2-stroke and the 4-stroke has lower vibration meaning less shaking your bike apart. Also, you don't want to let your engine rev without load.

I was able to get my build together for about $250 - $200 gas bike kit and $50 bike. It has been a blast riding. Next build for me would probably be a custom Predator or LiFan fat tire bike.
 

HeadSmess

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May 17, 2010
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Is there common problems with 4 chokers?;)

cheap nasty gearboxes/kits. invest wisely!

not changing oil at least three times in the first few hours.

puttering around and not giving them any load in the first few hours.
not letting them warm up before thrashing them

they are all too wide for comfort!
 

bluegoatwoods

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Mar 23, 2008
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Following the advice of another member, I've started breaking in 2 strokes by using just about the same amount of oil as I had used after break-in. That's about 50:1. Though I did fatten the oil just a little bit on the first gallon. Results seem to be okay. I'm not sure I'm ready to recommend it to others. But it doesn't seem to be bad practice, so far.

I have heard that you shouldn't break in an engine going smoothly at any particular rpm. You should vary the engine speed. Up and down. And I'm told that it's good practice to scream on up a short hill from time to time during break-in. Again, not for too long at any given time.

Almost off topic, but might be useful:

Polyurethane varnish makes a pretty good thread-locker. I put it in one of those plastic ketchup squeeze bottles. You can get the point of the bottle into some pretty tight spaces and squeeze a few drops onto the threads. You won't get much on your hands and it'll keep those screws and bolts from vibrating loose. But it'll also be easy to break them loose when you need to.
 
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