The definitive break-in procedure thread.


New Member
Aug 29, 2008
Tucson, AZ USA
No, I do not mean burglary! :p I am looking to lump the ideas of all of you experienced riders to outline what you beleive is the proper method for breaking in a china girl engine and if possible tell why it should be so.

What I've managed to scrounge up is as follows:

Use Valvoline 2-cycle oil for the first 2 gallons of fuel then switch to synthetic.

Idle the engine for 10 minutes and let it cool before riding with it.

Do not run the engine more than 10 minutes at a time for the 1st 50 miles.

Do not run the engine full throttle or for more than 20 minutes for the 1st 500 miles.

Run the Fuel:Oil ratio at 20:1 for the 1st 500 then you can lighten up on the oil.

Am I right, wrong, or totally wacked?


Master Bike Builder & Forum Sponsor
Dec 28, 2007
Duvall, WA PNW
There is nothing wrong with getting on it hard fairly early in life. Some of that is whacked.....sure bogging it or constant RPM is not good early in life. OTOH, babying an engine too much just extends the time to properly seat the rings. I read this stuff about people taking 400+ miles for the engine to break in, and that tells me something isn't right.

MAYBE 20:1 for the first tank, but even....

In my case I never did that. My first tank was 30:1 or so, I was battling the usual HT tuning and set up issues, once I got that stuff out of the way, second tank 32:1 the engine started getting more power, maybe third tank power got up to the point where it is now. Nice and well broken in.

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
up north now
Now, for break-in.

24:1 fuel oil mix for a tank, then run 24-32:1 thereafter.
Don't beat on the engine, but don't baby it, and don't be afraid to rev it either.

VARY THROTTLE POSITION AND ENGINE SPEED REGULARLY (A LOT) during the first 10 minutes, and still use a lot of differing throttle settings/engine speeds for a couple hundred miles thereafter.

Idealy, for the first 10-30 minutes you should allways decellerate slowly, taking about twice the Amount of time in seconds you used to accellerate. ie 10 secs. speeding up, 20 seconds to slow it down ect.


May 25, 2008
Sad but true. To break in a chinagurl, I use what ever oil is in the shop. 6oz to a gallon, then 4. Keep it under 20 mph until the engine kicks up on power and check the mounts just as soon as they fall off. I have never replaced a stud but lots of nuts.
It just gets worse, so I digress.

In the great words of Mark Twain; "No man is a complete waste, he can always serve as a bad example"


minor bike philosopher
Jan 15, 2008
north carolina
I live in an area with hills. I broke mine in full throttle up hill and half throttle down hill. I changed the oil mix otherwise I ride it the same now.


Custom MB Buiilder
May 7, 2008
Houston, Texas
32:1 and common sense go a long way. A constant throttle for a new motor will not hurt it, it will not help it either. Vary your speed for the first 2 gallons if you can. Change the mix ratio after a few hundred miles. 20:1 is cool. Abuse is not a warranty issue. Use your common sense. That's why you have it. I use amsoil. others will work, I have never lost a motor using it. I use Castrol GTX in my other bikes. At 200 mph oil is something you don't need on your mind.


New Member
Mar 23, 2013
central western nj
Warm it up then ride it like you normally would.Any 2 cycle motor would blow up after being ran WOT for to long,,just use common sense,,keep an eye on the motor temp and how she is responding,,also lean up the mix after a couple tanks,,but all this running it no more than 10 minutes is horse hockey.Get on it and ride!Ive been racing and building 2 stroke engines for over 35 years and always broke em in like I was gonna ride em,,never had a problem.Did you break in your weed eater,chainsaw,or blower when it was new?
Nope,,you brought it home and ran it WOT right out of the box and it never mattered.I have the same weed eater STIHL FS-74 from 1995 and ran it WOT from the start.It runs like a champ and I cut alot of grass in the Summer with it every year.Life is too short to be breaking things in like mentioned earlier in this thread,,get out on that motorized bicycle and have fun,,let me know how it runs :)



Well-Known Member
Feb 28, 2010
I like 25:1 then 32:1, 2/3 Cup and the 1/2 Cup per gallon respectively.
Generally it's a ride around the block with a little WOT in the middle and then idle for awhile.

After that it is just give it a rest after 15-20 minutes for a tank or two, especially here in the summer desert heat.


New Member
Mar 23, 2013
central western nj
Just got back from a ride around town,,still in my first ten miles on the motor,,I ran it WOT for a few bursts but other than that just kept it at a respectable cruising speed,,I would not recommend running these china girl motors WOT for long periods of time,,especially with a 44 tooth or larger sprocket,,,you could possibly get away with it on a 36 tooth for a while longer.Just cruising around town I can see this little motor lasting pretty long as long as you snug everything up once in a while and keep up on it.Lots of fun so far.I plan on selling this one after she is broke in,,and building more.
Good Times!



Active Member
Mar 17, 2012
North Bay
Kart racers break in their newly jugged 50-125cc engines usually within one practice session of 25 minutes or so. The big concern is getting the rings to seat well.


Old, Fat, and still faster than you
Oct 8, 2011
memphis Tn
Originally Posted by 2door
I have to concur. When I first started with this hobby I tried to follow the manufacturer's recommended break-in procedures with my first engine.

Not anymore. They get rode hard and put away wet, right out of the box. And you know what? All of my later engines have performed much better than the first one that got treated softly. Never had an engine/bearing/piston/ etc. failure of any kind.

Ever see a woodsman baby his new chainsaw? Ever see a yardman running his new weedwhacker at 1/2 throttle? Bet ya ain't.


Could not have said it any better.
Ride it hard and put it up wet.
40+ years of two stroke riding, tuning, racing and generally messing with every kind rind dinger you can think of, from tiny rc glow engines to huge industrial and marine two stroke diesel powerplant engines.
Owners manuals don't care HOW your engine runs, just HOW LONG your engine runs. They totally overdo their instructions to reduce warranty returns from inexperienced users.
Any real two-stroke old timer will tell you the same thing.
At least the fast ones...

I want to find any weak parts right away, not 75 miles from the house.


Jan 7, 2012
San Francisco, CA.
Oh boy not another break in thread... : )

I agree; my engines get driven as I am going to ride them from the very beginning. Now I do have to say that a lot of high rpm isn't great before the parts sit but full throttle is fine.

I have a massive 5 mile hill/loop which is great for breaking in... full throttle but not high rpm. You can FEEL the rings wearing in perfectly against the cylinder when you drive up it.

I run non synthetic cheap oil for break in at 24-1 for break in. Once broken in I switch to 32-1 red line synthetic but some say thats a lot... I like a lot of oil! -MOTO