Engine break-in

[00wyk]

I found this interesting. They tried to do two completely different break-ins on a motorbike to see how it affected the engines. Yeah, it's not a two stroke, but still interesting. Aside from the ring end gaps, they were nearly identical after 1000 miles. The ring end gap is not really a surprise. But it is interesting to see how it made little difference otherwise. They used Bel Ray oil.

 

[00wyk]

 

[Marshy]

Imagine all the fun missed by the rider of engine #1 babying the bike. No thanks! The best an engine will ever run is right after its rebuilt so enjoy it while it lasts!

 

[Chainsaw Jim]

Id say the most important thing about breaking in a saw is to maintain the right tune during the process. They like to lean out at least one good time as the rings seat.

 

[Al Smith]

Oil it up and run it rich for a few tanks.Then lean it out and flog it like a rented mule .

 

[67L36Driver]

I’ve never been worried about rings and such as I use a good bit of assembly lube.

What I am concerned about are the lip seals. They start out tight and might overheat and melt the rubber. So, they get a goober of EP grease at assembly. [emoji1696]

 

[Marshy]

One thing I did read and never got the chance to try was the difference between using WD40 on the rings vs motor oil.

The old school method I heard was to coat the piston and rings in motor oil during assembly.

The new school way was to lightly spray the piston and rings with WD40.

I guess the thought was WD is thin and allows the rings to bed in the cylinder wall faster. The thick motor oil doesnt allow the rings to make contact with the bore and can glaze the bore. I guess the oil in the ring glands can carbonized and also cause ring stick.

 

[huskihl]

One thing I did read and never got the chance to try was the difference between using WD40 on the rings vs motor oil.

The old school method I heard was to coat the piston and rings in motor oil during assembly.

The new school way was to lightly spray the piston and rings with WD40.

I guess the thought was WD is thin and allows the rings to bed in the cylinder wall faster. The thick motor oil doesnt allow the rings to make contact with the bore and can glaze the bore. I guess the oil in the ring glands can carbonized and also cause ring stick.

I can't imagine that any kind of assembly lube hangs around long enough make a difference either way with a fog of gas and oil droplets being sprayed everywhere.

 

[Al Smith]

When I rebuild any engine I don't spare the oil .If it doesn't blow blue smoke for a few minutes I fear I didn't use enough .

 

[Wonkydonkey]

If anything the oil gives more compression, and excess gets burnt off and spat out of the exhaust. 2strokes are not the same as 4stroke, in that we have oil in the fuel, and 4 stroke its in the sump and may take some time to lube the cylinder wall.

Anyhow when I assemble a 2stroke, I lube everything with straight 2stroke oil. As it takes time to lube the little end

 

[Jetwrench]

Just my 0.02 but I was in the lawn biz for several years and always broke in my new hand helds (stihl and redmax) at a large cemetery I was contracted to maintain. My trimmers were warmed up from brand new and then ran wide open for about 45 min which is about how long it took to trim a row of head stones. After that they were refueled and allowed to cool for about 15 min and the cycle repeated. In the first day they had 4-5 tanks ran thru them. It seemed that they were the best running and easiest starting engines I’ve owned.