My thoughts on chinadoll break-in procedure.

maniac57

maniac57

Old, Fat, and still faster than you
I run 40:1 right from the start, riding normally with no full throttle over 5 seconds or so or going above about 6k rpm for more than a few seconds the first tank, gradually holding it open longer second through 4th tanks.
On the first tank I make sure to do LOTS of full throttle pulls from fairly low speed, just little blips up and down through the rev range but not going all out.
I gradually hold it wide open a bit longer and higher up in the rev range 2nd thru 4th tanks, at which point you're good to go usually.
As the engine loosens up and seals, you will feel the difference in midrange torque.



Notice the nice even wear pattern on the ring faces and the minimal blow-by discoloration underneath the rings. This indicates a good even ring seal with little leakage or lost compression and good contact with the cylinder walls.


You can just barely see the ring at the top of the port and it has no more than 1/8th" or so of discoloration below the rings.
This is what a good seal looks like in a chinadoll.

This engine is on it's second tank using the above process.

Been doing all my two strokes this way for decades and it works great for me.
Your results may vary.dnut
 
Sound like a plan. Look at all the small 2cycle stuff that gets 50:1 for the first tank right out of the box then goes out and blows/trims/cuts all afternoon. I worked for a major chain saw manufacturer. The recommended pre-delivery run procedure start the saw let it stabilize a bit hold it wide open for 90 seconds, let it run just above idle to cool a bit shut it off and give it to the customer.

Your method is down right civilized M57!
 
Yup... works for me too... On my last build I just went straight to 100:1 Opti2 and coasted it down the hill twice with the clutch out and the plug not yet installed, then installed the plug and it fired right up, took it for an easy 5 minute ride staying close to home and let it cool down. After this I ride it as intended but keep the rides under 10 minutes and the full throttle bursts short at first, as the engine loosens up I'll run it a bit longer with the full throttle bursts before backing off. I don't let the engine run at a steady rpm either and I'll run it up to top speed then back off and just keep changing the throttle position and rpm.

Most important is to just be sure the engine can't overheat and I do this by keeping the trips short at first, then go a little longer as it loosens up. Somewhere close to the end of the second tankfull of gas is where I usually feel the engine get a little stronger and faster each time I ride it for the next several rides then it'll finally level of where it won't improve any further and that's where it's fully broken in.

I also keep a close eye on my engine's internals by removing the pipe to inspect what I can of the piston and rings looking into the exhaust port, then pull the plug and send a borescope camera into the cylinder to check for any abnormalities, and can se the underside of the piston thru the intake with the piston at TDC with a borescope camera and a mirror attachment. The underside of the piston should be a brown color and shouldn't have any signs of blackening or ash. The piston crown should be clean for the most part, some browning is normal, but shouldn't go totally black and definitely no ash should be there either. Not much else to look at inside the engine but everything should look about the same as before it was run other than some browning on the piston crown and underside.
 
I think the heavier oil is to help carry away shavings and make things run a bit cooler. Short throttle burst are to seat the rings, eh? Extra pressure from a hard throttle twist really scrubs the rings in good.
 
Eric2.0 said:
I think the heavier oil is to help carry away shavings and make things run a bit cooler. Short throttle burst are to seat the rings, eh? Extra pressure from a hard throttle twist really scrubs the rings in good.
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Exactly. The high pressure pushes out on the rings and helps with good seal. Running it like a weenie can lead to tons of blow-by
But no full rev screaming
 
Yes, Maniac. I recall in the past you've mentioned that you break-in at 40:1 and I've been intrigued. I might try it one of these days.

I've wondered what the pros and cons might be. It sounds like one advantage is a good, clean break-in. Is there any reason that a thick break-in mix might not achieve the same thing?

From the posts above I gather that we want to goose that throttle to fairly high rpms pretty quickly in order to seat those rings well. We don't want to run long at one particular rpm. But when going up, we hit it fairly hard. Have I got that right?
 
Back when I was an auto mechanic 25 years ago and did a fair amount of engine rebuilds both stock and hot rod, this was my break-in procedure. Usually in an evening after I got it all put together I would head out with the vehicle with the newly built engine and a box of tools, grab myself a 12 pack of beer, maybe a friend or two and even more beer. Spend the next 4-6 hours cruising around, some easy, some wind the snot out of it smoky burnouts. Some stuff the owner probably wouldn't appreciate. The next morning I would check everything over, reset the timing and valve/rocker arms. Then give it to the customer with a little speech on taking it easy for a while. This method never failed me and it was a lot of fun.
 
i guess ill have to be the odd man out here.....

whatever mix i plan to run in my engines is what they get from day one, i take it fairly easy for first 12-15 miles and then i run it like i plan to run it.

my engines all run very good, no oil or high rpm related failures, they all have good compression also as rings always seat in well.

I have never babied any of my fresh engines, but i do give them a very short few miles to make sure they're running like they should and all fasteners are staying put, then I wind her up and begin to see what she has knowing the initial results will i.prove after a few more miles.

im usually running mina all out before i get 3/4 of the first 2liter tank run through it.

Im not saying my way is the right way and im not saying my way is the best way, im say this is my way and my way works great for my engines.

map
 
"i guess ill have to be the odd man out here.....

......Im not saying my way is the right way and im not saying my way is the best way, im say this is my way and my way works great for my engines." --mapbike

Fair enough. Though it doesn't sound as though your way is so different from what Maniac57 does.

Here's how I'm interpreting it all. How much oil you use matters less than how you run that engine during break-in.

Don't over-stress it and keep varying the load.

Makes sense to me.

I'll be breaking in an engine soon. Perhaps I'll go just a bit thick on the oil. But maybe I won't go double strength.
 
My thinking is that extra oil simply makes the rings that much harder to seat. As long as it has enough to prevent galling and extreme wear it's good even during break-in.
I'm with map. I run all my engines on the normal ratio from day one whatever that might be.
I use 40:1, but 32:1 is fine as well. I would not go any richer myself, but I'm set in my ways.
With modern oils, there is simply no reason to go richer unless you are riding extremely hard or pulling stupid high revs.
 
maniac57 said:
My thinking is that extra oil simply makes the rings that much harder to seat. As long as it has enough to prevent galling and extreme wear it's good even during break-in.
I'm with map. I run all my engines on the normal ratio from day one whatever that might be.
I use 40:1, but 32:1 is fine as well. I would not go any richer myself, but I'm set in my ways.
With modern oils, there is simply no reason to go richer unless you are riding extremely hard or pulling stupid high revs.
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I agree completely maniac.
 
I agree too... Last one I built I just poured in some 100:1 I already had mixed up and went for it... no problems at all.
 
I did the whole 20:1 the very first build I ever had that was completely stock and now I think the only thing that changes dependability during break in is the user themselves, it's the crap they put on or tinker with that will change whether or not the motor will live or not. Break in or not.

The second motor I didn't break in at all just went straight to what I would normally run and never had any problems or differences between the two running wise. To each there own I just know that I hadn't had any problems running 50:1 right off the bat with a new motor and now it's running 80:1 with some better oil.
 
Actually I've found that lying works for me. When I'm filling the tank for the first time I tell the engine that it's a 24:1 mix. Then I go out and ride the heck out of it and the engine doesn't seem to know or care that it just got Opti-2 @ 100:1. Not one has ever come back to complain :)

Tom
 
2door said:
Actually I've found that lying works for me. When I'm filling the tank for the first time I tell the engine that it's a 24:1 mix. Then I go out and ride the heck out of it and the engine doesn't seem to know or care that it just got Opti-2 @ 100:1. Not one has ever come back to complain :)

Tom
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Sounds like my parents when they would take me to chinese. Yeah honey these are chicken nuggets you'll love them! Just sweet n sour chicken with no sauce on it.... They know... Oh they know
 
maniac57 said:
Exactly. The high pressure pushes out on the rings and helps with good seal. Running it like a weenie can lead to tons of blow-by
But no full rev screaming
Click to expand...


Yepp, if you don't scrub the rings in good, they'll slap the cylinder silly and have no power.

I'll remember to do this when I get it running next week. I'll also use 40:1 gas oil, rather than 16:1.

Makes sense with these new oils, don't need tons of it in there.

BTW you use synthetic from the start?
 
No. I use normal oil for break-in. Full synthetics can be too slippery for good break-in.
Switch to synthetic after break-in.
 
I'm giving it a try right now with a brand new 66 cc. I made the fist two short runs on Sunday. Very short and local rides while I made drive train adjustments and such.

Yesterday I took a few slightly longer rides. Between one and two miles each. Never 'wound it out'. Just cruised along, mostly, and goosing it fairly gently from time to time.

Engine starts well and ran smooth with only one short period of four stoking on one uphill. It won't idle yet. But I can keep it from stalling when dis-engaging the clutch by throttling up a bit.

This engine seems to want more choke than previous engines. I'll be looking for intake leaks today. But I doubt if that's the case. I installed the intake and carb carefully.

I'm using "Peak" two cycle oil. Mixed at 50:1. Does all of that sound about right?

Or does anyone have suggestions?
 
Wait, there's more.

This throttle seems to be a bit more sensitive than on my previous bikes. A small twist will send the rpms higher than I was aiming for.

One difference is that I have a longer, offset intake than what I've had before.

Can that explain the differences I'm noticing in choke and throttle behavior?
 
bluegoatwoods said:
Wait, there's more.

This throttle seems to be a bit more sensitive than on my previous bikes. A small twist will send the rpms higher than I was aiming for.

One difference is that I have a longer, offset intake than what I've had before.

Can that explain the differences I'm noticing in choke and throttle behavior?
Click to expand...

very well could be, Ive only used one of those long dog leg looking intakesa couple times and both time the idle of the engine was affected, both of those engines idled to high for my liking, its been a few years since I ran one so I dont remember exactly how they acted but I honestly didn't really like how they run with those extra long intakes, mainly I think it had to do with throttle response andneither of them had as good of an idle quality as they did when I switch them over to the shorty manic intakes, then eoach had a crsiper throttle and the idle quality was much better.

Of course on some builds the dog leg intake is needed and they do work, but I would ever use one again unless I just simply had no other option.
 
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