break in period

[robsgreen]

Hi Guys

My engine is running really well since I completed the rebuild and I'm pleased that my carbs haven't leaked once since they have been back on the bike.

My question is, what is the break in period and revs for the engine. Ive put in a re-ground crank and new shells, primary and cam chains, new pistons and rings etc.

Someone told me to run it no higher than 4000 rpm but never full throttle for 500 miles and then gradually increase the rpm over the next 500miles.

What do you guys recommend?

Regards

martin

[daves79x]

First of all, I'd be changing the oil/filter and cleaning the sump out at 100 miles - no more. You might be surprised at the debris you'll find. Hopefully mostly just stuff from the reassembly process and not much metal of any kind. You will see tiny flecks of babbit from the bearings wearing in. This will have cleaned out all the junk. Then run it no more than the 500 mile mark and do it all over again. If the sump is clean, you're good to go then. After that, run it however you want - you won't hurt anything. A few blasts to redline helps seat everything in.

Dave

[EMS]

As far as engine loads is concerned, for the first 1000 miles, I would try to run it at varying speeds. Try to avoid holding it at red-line for extended periods of time and NEVER go full throttle out of lower rpm. Definitely stick to the oil changes as Dave recommends.

[asacuta]

http://www.mototuneusa.com/break_in_secrets.htm

[robsgreen]

Hi guys
Thanks for your help, interesting. I understand what dave says and that makes perfect sense and also trying to vay the engine rpm, but I would have thought I had to limit the amount of revs used? I don't fancy pushing the engine hard as per the link.
Best regards
martin

[asacuta]

You may be interested in the break-in procedure the Honda dealer gave me when I bought my 81 CBX: "Do not follow the instructions in the owner's manual; ride the living snot out of it or it will burn oil."

[EMS]

I don't think there should be a concern regarding limiting the revs. Getting the motor to red-line should not be an issue. Holding it there for longer periods of time, could be. Also, "riding the living snot" out of it, is an advice that leaves a little too much open to abuse. One of the worst things you can do to an engine is ripping open the throttle at low rpm. Full throttle creates maximum pressure above the piston and maximum downforce through the rods on the crank journals. At low rpm, the rotating masses provide inadequate balance for that force. That would be a concern, especially on a re-ground crank and new shells.
As far as the link is concerned - yes, engine technology has made progress. But you still have a 35 year old motor by design. I don't think you can easily apply how you treat a modern sportbike to a vintage engine.