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Yes just like a top end ring job. I even have a case of break in 30 wt oil I use just for this. About 8 years ago I overhauled a GPZ1100 and used my usual oil for breakin Rotella 15-40 wt like I've done dozens of time. I went for my break in ride but I could not get the rings to seat, lots of blowby and low compression. Tore the top end off de glazed the cylinders and put in new rings. Use the same oil and my break in procedure. Again lots of blowby and low compression, very frustrating. Tore the top end off again de glazed the cylinders, new rings again but this time I put in break in oil. Did my break in and this time great compression, no blowby and ran fantastic.
Did a bunch of research and discovered the oil companies are making their oils so good it's not allowing a good bed in on the rings. The break in oil has no friction reducers its like the oil from 30 years ago.
I am curious where did you find the info to let the engine idle at 2500 rpm to heat cycle the engine? I've been building motorcycle engines since 1976 and have never came across that one.

www.kzrider.com/forum/2-engine/607610-st...engine-after-rebuild

There ya go, that's where i found it. Even on there it says 5 min so obviously 15 min was an exaggeration. Like I said I went off of temperature so my internal clock is a tad off.

Build it... Start it.... Ride it. Job Done.
Just don't thrash it or cruise at a constant speed/rpm out of the gate.
Use engine braking to push the rings into the bore.
No need for idling at whatever rpms unless you want to risk glazing the bores and no need to limit the max rpm's for any specific time or mileage period .

Yeah I was engine breaking as often as possible during those first 100 miles and varying my rpm. Maybe that was my saving grace as far as the whole glazing issue. Just made sense to me to heat cycle and get the head nuts torqued down properly before actually riding it.

Just remember for the next time, NO idling even a high idle start it and ride it. Also when you swap out heads be aware as you pull the old head off you will disturb the base gasket and could cause an oil leak. Whenever I work on a head I always remove the cylinder and replace the base gasket just so I don't have the customer coming back with a leaking base gasket later. I use that opportunity to de-glaze the cylinder and if the rings are good I'll reuse them. After getting it all back together I'll do my break in on the engine.

Like Baldy, I follow the same bedding In . I go for a ride and constantly torque the motor to 4K rpm . After checking the engine I keep on torquing now and then and prevent constant speed.
As stated idling to long glazes the bores/ rings. I never understand why riders (in Australia where its warmer) warm up the bikes every morning for 5 to 10 minutes or more.

When installing a freshly-honed cylinder block and new rings (top-end below the head only), how important for carb jetting and synchronization to be correct for startup and break-in?

I assume the previous carb settings will be close enough to start with, but for how long...considering the sync process may involve a period of extended idling time?

Unless you have some unknown combination of parts on the bike the jetting and state of tune really doesn't matter as long as it's ridable just ride it. Seat the rings then tune it later. Ive built some engines with wild cams, ported heads, big pistons, big carbs, ect. I tune the carbs prior to start using my past experience on jetting. It's not perfectly tuned but good enough for bedding in rings. The bike doesn't even need to idle correctly afterall no idling remember?
What a lot of people don't realize is you only have one chance at breakin. Do it wrong and it requires a top end teardown, de glaze and rings. No amount of riding trying to bed the rings will work once the cylinders are glazed. Like I mentioned earlier break in occures in the first 15 to 20 minutes of it running. That is a narrow window so if you let the bike just sit there at idle all your doing is risking glazing the cylinders. Do your tuning after break in,

This is all great advice guys I appreciate it. When i get that new head I'll probably just take it down to the base gasket and do like you said. Ill already have the head off so why not?
Yeah i just stuck with the same jetting i had before hand (plus a dynajet kit so guess the needle IS different). Mine isn't that radical of a change all i figured it'd be close enough to break it in so i could work on tuning like you said to do baldy110.

Been building engines for over 40 years and grease both sides of the base gasket ( in fact all paper gaskets ) and it stops them sticking and tearing on removal and aids settlement when bolting down.
Have re-used many gaskets with no issues once treated like that.
Never had one leak when i've had just the heads off for whatever reason.

zed1015 wrote: Been building engines for over 40 years and grease both sides of the base gasket ( in fact all paper gaskets ) and it stops them sticking and tearing on removal and aids settlement when bolting down.
Have re-used many gaskets with no issues once treated like that.
Never had one leak when i've had just the heads off for whatever reason.

I worked in a small shop while I was in college (auto mechanics). My boss required me to grease up all intake and exhaust gaskets prior to installation. The intakes came off easily and were reusable and the exhaust gaskets burned the grease into carobon which also came apart easily. The grease works great IMHO.

The last time I replaced my OEM base gasket, I put it on dry, and it is showing no leaks. I need to redo those pesky O-rings due to some slight seepage, but plan to deglaze and replace the base gasket again at that time. (not a big priority) I still need the APE studs, so this will wait until I can get a set. I also plan to glue this top end together like pitstop joe does it.

www.pitstopperformance.com/top-end-assembly/

You get no leaks cause you grease the base gasket Zed. I spray all my base gaskets with copper coat. That also prevents the gasket from sticking so i get no leaks when I pull only the head. The problem is when I have to pull the head on a bike I've never worked then I have an unknown so I simply pull the cylinder that way I know for sure it won't leak later. I HATE doing a job twice.