Break-in Period

Sassifrasstea · #1 07-19-2008, 11:37 PM

How many miles is the actual breakin period for a 70cc? I have looked all over this small town for a synthetic oil. All I could find is Lucas semi-synthetic. Is this ok. Also I may be rushing things. I have used 2 tanks of gas at 20:1. The instructions said run about 2 tanks of non-synthetic for a couple of tanks, then synthetic at 40:1. I mixed some of this semi-synthetic. I used 1 1/2 bottles of 50:1. I figure that would be about 38:1. Am I way off the mark?

misteright1_99 · #2 07-19-2008, 11:51 PM

What size bottles? How much gas?

**Dave31** · #3 07-20-2008, 01:06 AM

Sass...the one that has done a triathlon, right??

Here is a link for oil calculations...Gas Oil Mixture Ratio Calculator

I've used the Lucas and loved how it did not smoke...a good synthetic will do the same.

I've been told 4 tank full so about 2 gallons for the break in. But I have also been told 2 tanks for break in????

I used synthetic for my break in and had no problems, so I believe you will be okay.

Easy Rider · #4 07-20-2008, 01:42 AM

I've been around 2 cycles for a long time but never truely understood what a break-in period for 2 cycle motors really does? I have to admit I'm guilty for never breaking in any of my motors. Maybe its because I have a heavy throttle hand or foot. I do however know the importance of seating my piston ring. I usually just spray a little WD-40 in my new cylinder (an old racing trick) or use WD-40 when I'm building a new motor and don't punch it for the first couple of minutes of running it and "BAM" ring is seated.
Can someone please shed some light on my ignorance?

**Dave31** · #5 07-20-2008, 02:21 AM

The purpose of the break in procedure is to gradually wear down the "high spots" on componets such as rings, piston, skirts, cyclinder walls, bearings and races, ect.....

A new or rebuilt motor, all machined parts are imperfect to a certain degree and have a "high" and "low" areas which must be mated to those that they roll or rub against to achieve a good running fit.

Easy Rider · #6 07-20-2008, 02:41 AM

Thanks Fairracing, I knew you would know the answer. That's makes sense especially on the chinese motors. That's probably why the piston bushing on my old motor needed to be upgraded to a needle bearing after a few hundred miles. haha
My Old Yamaha Super Jet was probably the closest thing I had broken in but it was done my the guy I raced for back in the 90's and to this day never been rebuilt and it still runs strong. However, my karts, scooters and bikes were never broken in and they all run great (knock on wood) haha
But then again they're all high quality motors except for my 149cc Lifan.

Bikeguy Joe · #7 07-20-2008, 07:45 AM

Seating the rings is a big part of the break in, the other 399 miles seats the rest of the moving bits.

Easy Rider · #8 07-20-2008, 11:23 AM

But aren't all the other parts precision bearing? There are 4 critical moving parts on two cycle engines and all of them are bearings. The two crank bearing, the connecting rod bearing and the wrist pin bearing. I honestly thought there was no need to break in bearings.
But I know that the chinese motors are not the same quality as the engines that come from Japan or Italy.

Bikeguy Joe · #9 07-20-2008, 11:28 AM

Not all of these bicycle motors have bearings, (ball or roller) in the wristpin location....some (most) have a bushing there.

Also, piston skirt clearance.

I was being a little sarcastic about the break in thing.....most of the ring seating is done within the first several minutes of running, (30-60).

cdoug50 · #10 07-20-2008, 11:30 PM

You might try WalMart for the two cycle synthetic oil. I found it in the lawn and garden section.