On my 89 flhtp I rebuilt the engine this winter from the bottom end up, valves, wisecoe flat tops etc so now if I can get some input for breakin. I do have the service manual but I'd like to hear from others if I can?
We have some nice doulble lane hiways that go for 30 miles or so in one direction so if I have to keep the mph down at a steady rate for a bit it's doable.

 

Well, there's no end of different opinions concerning break-in and I won't claim mine is better than anyone elses, but I'll give you the short version...

It's good to start it up and let it run fast idle (1200 - 1500) for about a minute and shut off to cool for about 20 minutes. Otherwise, if you're not going to ride it, don't start it! The first 25 miles or so are the most important. Go ride it keeping under 2500-2800 rpms and either be accelerating or on a hard decel. Steady speed/rpms is a no-no. As it warms, make the accel with more throttle but under 1/2 for sure. Keep that up for 25- 50 miles then park it and drop the oil immediately. Change that out and then go ride (whenever) avoiding steady speeds, lugging or sitting in traffic but wind it on up to about 3600 once in a while and again, avoid steady speed/throttle running all you can. After 125 - 250 you shouldn't notice much oil loss but you can expect up to 1/2 quart up to that point and don't worry about it. Change the oil again after about 500 miles and enjoy your new engine

 

I was going to offer advise but t150vej covered it real well. Good on him. That's exactly how I do it. I have nothing to add.

 

I learn more every time I come to the Evo section!! Can you explain the reason for not staying with a steady rpm? I have never heard this before but I will be doing my 88 some time late this summer.
Thanks!
Hatch.

 

I'm thinking it has to do with the rings seating and not hitting there peak in the cylinders.

 

The only thing I would add is during the initial startup you should run at a high idle until the engine warms up and shut it off, maybe seven to ten minutes. Then let the engine completely cool before starting it again and then ride it like you stole it.

Just remember evos and earlier make no oil pressure at low idle and idling these engines will kill them.

 

What T150 stated. I go a little bit further and "heat cycle" a new engine as described four times with fans running high speed on the engine. The it's off for a 50 mile ride keeping the rpms as is described. Change the oil and filter again at 500 miles and go for it.

 

The reason for that is because it takes very little throttle to run at steady speeds unless really fast, like 80+ and there is little pressure from combustion forcing the rings outward against the cylinder walls. That outward pressure from combustion getting behind the (top) rings is what actually seals them against the cylinder wall anyway, as well as high-speeds at light throttle can cause them to run a little hotter since there is less air/fuel going thru under those conditions. Cylinders are finished much smoother than in the old days and if it's run too lightly (no enough load) then whatever "rough" there is left from honing, is gone before the rings fully seat. If it's honed rough, it'll break them in too good, but that tends to wear away too much of the rings. Rough was the norm long ago with paraffin based oils, but modern motor oils are much better and need less wall texture to cling to. So a rough honed wall can hold too much oil and cause excessive use.

But again, it's not rocket science and main thing is to not lug or over-rev, get caught in traffic jams and overheat the thing. And some may disagree, but in my thoughts, "heat cycling" is as more for the benefit of gaskets rather than the rings, especially the head gasket. Hard parts (rings, cylinders) already went thru a super high heat process at manufacture and if you get them hot enough to change any of that, you've already cooked it down... but it will get the jugs hot really quick first time you fire one after hone/rings. That's why most agree to run them a very short period and shut them off to cool before riding and that gives the head gasket a chance to seal before putting full running compression to them.

 

This is some very good information. I had been reading about a method where as you get yourself to an area such as a double lane and shift to 3rd gear and now hit the throttle 3/4 going from 30 mph upto 60 mph and let off the throttle and once it goes back down to 30 mph hit the throttle again to 60 mph and do this 10 times to seat the rings. Is this familar to anyone?

 

I like Rufus' method better.. With the cylinder growth of an air cooled engine, temperature is very important and doing the 3/4 throttle, on and off, may cause gasket issues.. There is a theory that "driving it like you stole it" will help to seat the rings at a higher level though, because of "rod streach" at high RPM's.. But, being air cooled and not a race engine, I dont believe thats the best way for longevity... I'm still learning the Harley engine stuff, so the other guys may have better info, but thats my take on things.. I recently did mine at random RPM's for roughly 200mi and was very happy with the results, runs good and no smoke..