Best way to break in a new topend?
- Thread starter smerch69
- Start date
There are 1000 different ways people will tell you. Personally i do one heat cycle on the stand while i watch closely and listen to the motor for anything unusual. Then i ride it under 1/2 throttle for 1-2 times for ~20 minute rides. After that i get to the rippin' and the tearin' as normal
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I usually will also let it warm up until it's pretty warm, shut her down, then go for an easy ride, no full Throttle, and run one tank thru it like that. Then it's ready to ride normally. But I know people that after one warm up on the stand, will run the piss outa it, and that seems to work for them.
I do the same as Steve with the exception of the full tank of gas. I only do two non motion heat cycles and one or two slow ride. each cycle about 10-15 minutes. Then RUN THE PISS OUT OF IT!!!
LOL I am one of the "other" 1000. The cylinder preperation has more to do with how the rings will seat more than your breaking procedure barring you don't get it really hot. To get the best ring seat with the least amount of glaze buildup, I use little to no lubricant on the cylinder. It is a very old trick. The bearings get plenty.
Then to get the rings seated a pretty decent amount of cylinder pressure early on (before the walls can glaze) works best for me. So I put a load on it. Just brief loads, and then load it again. Mx couses with short hills work nicely. FYI if you ever heard of engines that are "broken in" on a dyno, they are "loaded". Just don't over do the oil or heat it to the point of seizing it and yours will probably work just fine.
Then to get the rings seated a pretty decent amount of cylinder pressure early on (before the walls can glaze) works best for me. So I put a load on it. Just brief loads, and then load it again. Mx couses with short hills work nicely. FYI if you ever heard of engines that are "broken in" on a dyno, they are "loaded". Just don't over do the oil or heat it to the point of seizing it and yours will probably work just fine.
But let's talk about steel sleave and nikasil? 
Now what's your methodology?
Now what's your methodology?
But let's talk about steel sleave and nikasil?
Now what's your methodology?
Mine is the same. Probably slightly more important to stay more on the dry side with the ferrous cylinder actually.
I am probably less critical of the warmup time on my air cooled ones than the liquid cooled ones. Some people have had a little trouble of getting the liquid cooled ones too hot on the stand and then hitting speed too fast on a cold day (no thermostats usually) and causing what amounts to being a cold seizure. The only ones I talked to were trying to heat cycle. It hasnt happened to me though in a WHOLE bunch of chances with anywhere from 1 to 4 cylinders.
My procedure for the air cooled ones has always been a certain amount dictated by the weather since running one hard before it is at least running smooth without the choke or enrichener new or old has sometimes left partially seized evidence on the walls (aluminum deposits).
My last few cylinders went together getting some atf rubbed into the cylinder with a clean cloth. dried down as far at the cloth would take it. it cleans the little partciles out even better than solvent will or brake clean that way. 20 hour tear downs have shown the closest thing to new cylinders that I have ever seen. That little procedure came to me from a man named Tryce Welch. Pretty simple and subtle but noticeable and worth the step. Tryce has built rigs that way for a pretty long time and was the man who built most of the stuff that the Haydens used before getting factory rides.
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if its just a piston and rings in an already worn cyl, then I just start it up at home to be sure it runs and no leaks. Then when I ride it for the first few minutes a I just go thru the gears and don't hold it wide open for mare than a few seconds. I then ride as normal. Remember its just piston n rings, everything else is already loosened up.
If you mean the one just outlined from Tryce, yes, quite a few times. Cast iron on an xr so far has been the only ferrous one, two and fourstroke plated cylinders both work nice with it. He probably had the first 65hp yz450f I ever saw a dyno chart on in 2003.
Before that my last clean on the cylinder was diesel and put it on dry. I am not sure if it is clear there, but on the two strokes I use whatever oil to lube the wrist pin and other bearings that I am going to use in the premix.
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I am not sure if you are referring to using ATF to clean and lube the cylinders or the practice if using a high viscosity oil to coat the rotating parts. That works really well in a plain bearing application. If your friend was a Vic Pickens disciple he was probably fond of spinning those engines over a long time before letting them start