[Peter]

Thanks Peter, I guess at the time I was thinking at 700miles I was mostly through the break in - and I had pretty much been babying it.  But that was my mistake, I guess.

I just torqued down the fifth stud like the others - not too much, 20 ft/lbs.

So, you are a synthetic advocate.  Interesting.  Maybe, I'll do search.

aleman

That's what I thought you probably did.
The problem is that simply equating a certain mileage with a certain stage of break-in is fallacious. You could have gone to 1000 miles just babying it and it still wouldn't have been broken in for an extended 60mph run.

However, by just recommending a rather high break-in mileage, odds are that conditions suitable for break-in have occurred often enough to decrease piston seizure risk. The reason for that is that it is really almost impossible to baby an engine all the time while riding in traffic. Particularly acceleration always puts high loads on the engine.

Still, an especially careful and anxious rider may end up babying the engine so perfectly that break-in for regular use has hardly started - even at a 1000 miles.

When I start an engine with a new cylinder and piston for the first time, I let it idle for maybe 30-45 seconds and then I shut it off. Time for coffee or cold beverages and some celebration because it didn't blow up immediately. I then let it cool down completely before starting it again. This is also a good time to check how hot the barrel becomes after that short a time idling (you will have to wait a bit especially with an iron barrel to get the peak temp). Just touch it and compare that with the temp a run in barrel develops after 30-45 seconds of idling... interesting.

Next I start the cold engine again and let it idle for 30-45 seconds and the rev it up a few times about as high as I would need to in order to ride off somewhat spiritedly. Engine is shut off after no more than 2 minutes. Time for another coffee and some cooling down. Also time to fetch gloves and helmet.

Next is a careful ride around the block, 1/2 mile after a minute warm up idle. By the time I'm back at the garage, the barrel is likely very hot. Time to shut the engine off and let it cool down completely.

Then I repeat the last step again and I may do that a couple of more times all the time paying attention to the temp because it should start to run appreciably cooler after not much total running time at all.

Even If I can't detect a difference in temp, I proceed to slightly longer babying rides of maybe 1-2 miles two or three times. Always letting the engine cool down completely between rides.

This takes almost a day for not more than ten miles of riding because of all the cooling down between the rides. I just do other things while the engine is resting.

At this point the engine is broken in for starting and careful riding off for short rides.

Next is loading the rings by going for ever so slightly longer rides and intermittently opening the throttle (fully warmed up and not lugging and not revving high) followed immediately by closing the throttle and engine braking. I allow the engine to cool down completely between rides.
This is controversial and I'm really not eager to get into an argument about it. I do it because I'm really concerned about the bore glazing over and I take my chances.

All this takes about 50-100 miles and all riding is in the neighbourhood. The last time I just kept the old oil (single grade paraffin - of all things) in for this period. Then I switched to synthetic, which will keep temps a little lower and is safer during break-in and overall in air cooled engines.

From here I keep breaking in the engine by systematically pushing the envelope in terms of load and load duration. All rides are relatively short and the engine is allowed to cool down between rides. I really don't pay attention to the odometer while doing this. After almost 2500 miles, my engine is fully broken in for 70mph sustained but only for about 5 minutes at 75 and short bursts at 80mph. The reason for this is that 70mph is plenty for where I am riding.


These are my $0.02 regarding breaking in a new piston and barrel.
Equating a number of miles with break-in makes no sense to me although I do agree that you do have to ride some miles for proper break-in.
An entire new engine is again a different matter and you need more time than with new piston and barrel only.

I believe you also have an alloy barrel.
Those with iron barrels will have to be even more conservative.


Peter




 
 

 

 

engine again  after   

[ace.cafe]

I agree that during the break-in process, you need to increase the throttle openings as you go along. You can't do it all at small throttle openings.

If you pay attention to the way the engine is responding, you can tell when it's ready to go a little more.

And the accelerations and engine braking do help to seat the rings, and it's important.

Droning along at a constant engine speed is not the way to properly break-in.
So you need to keep varying that throttle and let it feel some accelerations and engine braking, and move up the scale as you feel it can do it.

[aleman]

Peter, Thanks.   That is a very good "recipe" and I think I will just go ahead and do it that way.  If nothing else, a methodology will provide some needed discipline, which would be good.

i am an alloy barrel, by the way.  Impressive performance stated for your machine.  You must have done something right.

aleman

[Peter]

Peter, Thanks.   That is a very good "recipe" and I think I will just go ahead and do it that way.  If nothing else, a methodology will provide some needed discipline, which would be good.

i am an alloy barrel, by the way.  Impressive performance stated for your machine.  You must have done something right.

aleman

Now bear in mind that my engine is happiest (vibration etc as well) cruising between 60 and 65mph. In RPM that is somewhere between 3600 and 4000 with an 18t sprocket. It just feels right, and it's also nice to know that there is still some money in the bank....

I got the 4speed tranny and I'll stick with the 18t. With the 5speed I would have changed to a 19t sprocket. I think that it would lope along nicely at 65-70mph on the flats with that.

I have to get over tall highway bridges in my area and I would have to downshift with a 19t and that's just not going to work well here with the low 3rd.

Peter

[soulforge]

Fascinating story to read!
Thanks to all of you!
This is just one of the reasons I LOVE this forum.

Hip Hip Hurrah~