Breaking in a freshly rebuilt motor

[NCAmother]

What is the preferred way to break in a freshly rebuilt flat tappet motor(1975 850t) for the first twenty minutes?  Do I just heat cycle the motor with rpms above 2,000? (While checking for initial leaks, oil pressure and timing?). I’m mainly concerned about the initial start up period before the motor sees any load.  thanks

[n3303j]

Run it under varying loads on the road to pressurize the rings.

[NCAmother]

Run it under varying loads on the road to pressurize the rings.

I’m more curious about the initial twenty minutes before the motor sees any load

[n3303j]

I'd want to start pressurizing rings immediately. Not give them 20 minutes to start them glazing. Some reliable sources state that ring break in, done properly, is mostly complete in the first 20 miles.

[Don G]

Watch a Cycle Garden video of Moe test riding a cycle, that is the way to seat the rings, keep it below red line though. A couple of blasts like that and she is ready for normal use. DonG

[NCAmother]

What about initial break in of the cam? 

[guzzisteve]

Initially 1500rpm, not below. Crack an oil line on head to make sure it has pressure. 

[Don G]

What cam grind and valve springs have you got? If stock, I would use SG rated oil and turn the idle speed up a bit as slow idling is not good for oil supply to the cam lobes, ride it moderately, for a few miles then give it some throttle through the gears and engine brake as well, lugging and babying the engine is the worst thing for it, don't be shy ride it. If you have some really radical cam and heavy valve springs all that I can recommend is use a set of lighter springs to break in the cam and lifters and then change the springs out for the heavy ones.  DonG

[NCAmother]

What cam grind and valve springs have you got? If stock, I would use SG rated oil and turn the idle speed up a bit as slow idling is not good for oil supply to the cam lobes, ride it moderately, for a few miles then give it some throttle through the gears and engine brake as well, lugging and babying the engine is the worst thing for it, don't be shy ride it. If you have some really radical cam and heavy valve springs all that I can recommend is use a set of lighter springs to break in the cam and lifters and then change the springs out for the heavy ones.  DonG

Cam is a regrind, slightly hotter than a b10, resurfaced lifters. 

[Moparnut72]

Can't say for MC engines but American auto flat tappet engines 2,500 rpm for 20 mins. No load etc. Then go seat the rings. The flat tappet come first, not done correctly can wipe out the cam. I would point a fan of two at the cylinders.
kk

[NCAmother]

Can't say for MC engines but American auto flat tappet engines 2,500 rpm for 20 mins. No load etc. Then go seat the rings. The flat tappet come first, not done correctly can wipe out the cam. I would point a fan of two at the cylinders.
kk

That’s my experience with v8 motors as well. Wiseco pistons recommend heat cycling several times

[cappisj1]

I followed this after putting gilardoni kits on my 850 T and my El Dorado. They are both doing great.

https://www.thisoldtractor.com/moto_guzzi_loopframe_engine_break_in___initial_start_after_rebuild.html