I just cant understand why there should be such a long a break in period for harleys? Presumably, HD use the most up to date production methods to make their engines, so why the need to run them in?? Other manufacturers dont specify such a rigid run in regime,. I can understand not thrashing a new engine for a little while whilst new, but why the almost paranoid need to be so gentle on the engines? Dont get me wrong, im not trying to question the quality of harley engineering or engines, but it does puzzle me a bit.

 

I never got the impression that you had to be super gentle on the engine during break-in. The say to avoid running the engine at a steady rpm for any extended period of time (such as a long highway trip) and not to exceed a certain rpm. I rode my bike on the backroads for the first 500 miles. Every now and then I'd goose it a little. Just tried to mix things up during the run-in period. The last time I bought a new car (Toyota), I believe the recommended procedure was almost the same as Harley's. You've got to remember, HD has a warranty to honor on a new bike. If they didn't tell you to be careful, sure enough, some egghead would take his brand new bike to the drag strip then scream when the motor came apart.

 

First 50 miles be easy next 450 never run at the same rpm for long periods of time... I don't think that's all that bad and most sportbikes are the same way if i remember.

Nothing unusual here

 

Being gentle or babying it is not beneficial at all, you must seat the rings rather quickly or you'll have an oil user on your hands and lower compression due to the rings not seated fully.

Here's a few topics to look over on it.

https://www.hdforums.com/m_153035/tm.htm

https://www.hdforums.com/m_122692/tm.htm

https://www.hdforums.com/m_70060/tm.htm

 

On a new build the first 15 miles will be the "live or die" for the rings. The rest is for bearings and and other wear items. I broke my new engine in on the dyno. I have almost zero leak down rate and the compression is great. I have done this several times now and it works.

No I do not wack it wide open instead you bring it up to rpms levels that keep increasing. What cause rings to seat is pressure into the cylinder which makes the rings be pressed intot cylinder wall. This type is break in is becoming more popular as the builder then can control how it is broke in and knows what the compression is and leak down before it leave the shop.

Verse's the ownr telling you how easy he was on it, this also makes for long lasting engine builds.

The 1000 mile thing is really for production builds as the tolorances are all over the place tight and loose so this allows everything to seat in and not bind or hammer itslef to death. Still there are engines that do not last,