Union Models

Out of curiosity, what's people's preference to running in a new YS.
I've bought a new YS70FZ. I've read some recomend run at tick over for a minute, then a slightly rich full throttle run for 3-4 minutes, cut the engine, let it cool and repeat the process for 30 minutes. The engine is ready to fly with.
Has anyone tried this method or stick with the usual fast bench tick over?

Mike.

Four Stroker

You will get a lot of different opinions here. Some are good for 185's. The 70 is a chromed aluminum sleeve engine. As with ABC engines I always break them in at roughly the temp. they are going to operate at. This means on the 70 set the idle air bleed to the 1 turn open recommendation and leave it. Run the engine up to full throttle and slowly click in the high needle until it just stops blubbering. If you can't hear blubbering, peak it quickly with a tach and back off 3 clicks. Should be about 1 and 7/8 to 1 and 3/4 open. Start at 2.

I run the engine up to full throttle for a minute of so, go to idle and let it cool down, repeat. One tank is plenty. Then fly conservatively which means to move the throttle stick slowly and not jam it wide open and complain the engine quit and start fiddling with the needles.

Union Models

Thanks for your reply. That sounds more like a kinder running in process that I'd be happy to use.
Running full throttle for 3-4 minutes feels a bit harsh for a new motor.

kenh3497

All the new engines I've broken in be they be 2C or 4C , I try to get a fairly reliable idle. If that takes one tank or two or three that is all the ground running I give the engine. I then put in in the plane and fly it. Keep it on the rich side and do lots of up and down lines advancing and retarding the throttle. The period of breaking in the ring is quite short. 90% ( give or take) should take place within the first 20 minutes or so. If you loose that window by to much ground running the engine will never develop it's full potential power. This web site tells you about a break in process I was taught way back in 1973 while attending a local tech school. The engine part was taught by a former GM district rep. The process is nothing new and has worked for every engine I've broken in no matter is automotive, lawn & garden or model.

Break In Secrets--How To Break In New Motorcycle and Car Engines For More Power

Ken

PS. The article is a little embellished but the process is proven

union model

Thanks for the link Ken, interesting read.