Break In Break In



I'm about to receive my bike + engine kit. I was wondering if anyone wanted to do a best-effort controlled break in comparison test. Here's the idea:

There are a variety of philosophies as to how our engines "should" be broken in. The proponents of each of these different camps could step forward to create a break in protocol. As detailed as possible: warm up time, fuel mixtures, choke position, terrain to drive on, etc.. No protocol should be so strict that reasonable users would never do it.

A user will then select one of the protocols based on what he or she judges is the best. Users report back over time. Ideally, we would measure some quantity, but who knows what that would be? These should be simple: Time to first failure, Speed (how to measure?) Power (even more difficult), MPG (I have no idea how this would be done.)

Over time, say we have 10 long term reports in each camp, we might be able to actually determine which break in method is the best. Sadly, the time to actually accumulate this information will probably be significant, and who knows if these kits will continue to exist, two, three years down the line.

What do you think?
I bet tests like this have been done with similar engines in labs and you could probably find the results online. There are so many variables such as gas, oil, mixture, temperature, storage location, driving conditions, etc that could affect the test results that it would be nearly impossible to be acurate.
Well, I know how I did it wrong on the second GEBE 25 cc I installed, have not repeated that mistake again. That second engine is on my goat chasing/pasture bike, never quite as fast as the rest.


1. I always use 93 octane major brand gas (Standard usually)

2. I mix 50:1, even have a felt pen mark on my plastic gas containers.

3. When everything is right, I put the bike on my rack, and burn 1/2 to 3/4 a tank out at idle speed.

4. I take the bike on long straightaways, for the first two tanks, no jackrabbit starting, always assisting the engine on any inclines to the max.
I vary the speeds some, but not as much as a 40 cc or bigger, where the breakin is more like a motorcycle.

5. This is a fact: when they hit 120-150 miles, (3rd or 4th tank)you can "feel" a ooomph in performance.
The following is my own break-in proceedure. I have broken in several 2 and four stroke engines including some ultralight aircraft 400cc+ two strokes.
I am not a certified expert, but I do have some knowledge with engines and the interviening 35 years of playing with them.

Having said that, I'll also say I haven't got one of the two prevalent Chinese manufactured engines just yet, but the following info pertains to most engines in general.

Break-in is a combination of heat cycling parts and allowing the rings to seat. This is taken care of by riding at moderate speeds followed by short periods of wide open throttle. Wide open throttle is necisary to seat the rings to bore properly. I saw a rather spirited discussion about this on the forums...this is not that kind of post.

A couple of observations- I see reading the forums that a lot of people are finding that these engines run better if the carbs are adjusted, and the intake gaskets are in order. If I were to break-in one of these (dax) e-bay engine, I would go ahead and set the carb and check the gaskets first. More on that later.

Another one is that the engines are suggested to be broken in with a 20/1 fuel mix. That's crazy, but I understand warranty issues. I'll just say use a good two stroke oil like Penzoil for 2 stroke air cooled engines, or one of the name brand synthetics (available at places like Wal-Mart in the lawn and garden/chainsaw/weedwacker area) and mix it in the 40 or 50/1 area AFTER BREAK IN.
If the carb is correctly set and the intake gasket(s) in order, begin break in....

To do an easy and proper break in, warm the engine until it will run with no choke then start down the road. Open the throttle to 1/4-1/3 and let it pick up speed for about 10 seconds, now back off the throttle and let it coast for about 10 seconds. Do that a few times. Next open it up to 1/2-3/4 throttle and let is gain speed for about 10 seconds, repeting the slowing proceedure as well. Do that several times then take it up to full throttle and let it gain speed for about 20 seconds, taking approx 30 seconds to decellerate each time. Increase the time you spend at WOT and decellerating until you are holding it wide open for longer than 30 seconds and you are about done.

Ride at moderate speeds with short runs of WOT until break in mileage is completed. You should notice an improvement in power and smoothness during the break in proceedure, and a gradual increase in performance for the next 100 miles or so.
You are correct BikeGuy Joe,

Thus far I'm a minority of one with the 25cc, I just like to pipe in sometimes on a technical JUST IN CASE another weedwhacker shows up one day.

BUT, 25 cc IS the exception to the rule, 50:1 from the get go, 20:1 will not do anything good to the smallest engine.

Glad you are aboard, quality info from the start, you won't take much breaking in yourself !!

Thanks for that!

I'm un-officially saying that all of these should probably go with 40 or 50 to 1 mix from the get go. But that's completely off the record.

I'm actually more concerned with the reports that a lot of these are having some lean carb/jetting as well as intake gasket issues.

NOTHING will kill a two stoke faster than a lean run via a bad intake gasket, except for running one wide open with a lean mix for too long.

Too much oil is just plain bad, and compensating for a lean mixture with extra oil is covering up a problem that will only get worse.

Did I mention that too much oil is as bad as too little oil?
Too much will cause plugs to foul and with that poor starting and low power, (not horrible, but not good) exhausts to plug up with carbon (bad enough and a pain to clean) and rings to stick (bad, or kiss it goodbye soon).

Also key with two strokes of any size is to allow a proper high idle warm up period to avoid "cold seizure".
I'll also add that 20/1 is probably O.K. if you were using old tech straight 30 weight oil, or the stuff they pass as oil in the country of origin.... :D
this is a little guide as what the guy that im buying my engine from
has instructed to do.

the following is in accordance to a 48cc 2 stroke engine
The engine is a 2 stroke design, therefore a petrol/oil mixture is necessary. During the first 500km break-in period, the ratio for engine is 16 parts petrol to 1 part high-grade 2 stroke motorcycle oil (65ml Penrite 2 stroke motor oil to 1 litre of 91 octane unleaded petrol). After the break-in period, the ratio is increased to 20 parts petrol to 1 part oil(50ml Penrite 2 stroke motor oil to 1 litre of 91 octane unleaded petrol).
Be sure to mix fuel and oil before adding to tank - don't add separately.
Do not exceed 20km/h during break-in period. Speed may be increased to 35km/h after the first 500km.

i have also seen a breaking in period chart which tells you what to run a different reached km.

going from what you guys are saying here it looks like the break in period is a crucial part to the engine as it determines how long your engine will last.. providing you take proper care of it
My bike now runs, a wire was broken and not easily spotted. Anyhow, carby is set and I have found what I would define as a "sweet spot" where pickup is a lot quicker and the engine barely vibrates. No shuddering at all once its warmed up.

I was going to ask if a little shudder, as if the engine was hesitating was normal, however, now that it has gone through a few runs, it seems to have settled. I must say, im impressed :) Starts quick and easy, and boy does it want to go.

After the engine is well and truly warm, I let it go a bit, open it up and get some speed up, then back off, letting it coast. I havent run it "hard" at all, although it seems to run much better at faster speeds.

I am running Valvoline 2 stroke oil for high stress/racing engines in the 16:1 ratio, is there any way to check if the engine is getting just enough oil? I know more about 4 strokes, theres no telltale smoke or anything.

Fox said:
is there any way to check if the engine is getting just enough oil? I know more about 4 strokes, theres no telltale smoke or anything.

Good oil doesn't really smoke in two strokes either with a 40/1 mix like most use. With the 16/1 mix, I can't say, but imagine it will be smokey!

If you are getting "just enough oil" you shouldn't see much on your plug. I'm still saying 16 to 1 is insanely high with modern oil.

Going back to the "wide open for short periods" thing during break engine is designed to run at wide open throttle and higher RPM. The "red line" on an engine is actually the maximum RPM the engine was designed to run at continuously. I know I will hear some argument on this one, but a true "red line" is one that the ebngine should be able to run at for it's entire "TBO" period. (hours be fore overhaul)

Also, a brief warm up period before loading the engine is essntial to a healthy (for a long time) two stroke. Once you fire it up, you should pull the clutch and let it run at a high idle for a couple of minutes before really putting a load on it.