Ironhead How long between heat cycles?

[78ironhead]

You have to run it to running temp, then seat the piston rings first, then shut it off and let it cool. Start it up and let it cool all you want, after you seat the rings.
The Problem With "Easy Break In" ...
The honed crosshatch pattern in the cylinder bore acts like a file to allow the rings to wear. The rings quickly wear down the "peaks" of this roughness, regardless of how hard the engine is run.

There's a very small window of opportunity to get the rings to seal really well ... the first 20 miles !!

If the rings aren't forced against the walls soon enough, they'll use up the roughness before they fully seat. Once that happens there is no solution but to re hone the cylinders, install new rings and start over again.

[Hopper]

Originally Posted by Beavis

Thanks all for the help!

Definately thing the full procedure should be made a stickey because its definately not in the FSM. Must have been in a yearly bulletin.

B

That's cos they never heard of heat cycles back in Ironhead days.
It is a recent phenomenon that has become a new age cult, probably because S&S recommends it. See the S&S website for the full rundown on their version.
But bear in mind they are talking about big inch motors with pot metal heads and barrels, not tractor engines with cast iron.

[IronMick]

Originally Posted by Beavis

How long between heat cycles ... I can't find the exact stickey ...

Originally Posted by IronMick

I do it this way - For heat cycles wait for the engine to completely cool down after each cycle, before going on to the next. 1st cycle 1 minute, 2nd cycle 2 minutes, ..., up to 5 minutes of running. [This is a modified version of what is posted in the Sticky] ...

Originally Posted by Beavis

... Definately thing the full procedure should be made a stickey ...

Originally Posted by Hopper

That's cos they never heard of heat cycles back in Ironhead days.
It is a recent phenomenon that has become a new age cult, probably because S&S recommends it. See the S&S website for the full rundown on their version ...

Here is the Sticky ...

break in period
http://xlforum.net/vbportal/forums/s...d.php?t=302136

As you may notice from reading the Sticky thread and from this thread the procedure is controversial, based on opinion, and not precisely specified. I read all of the opinions and decided to do it a certain way not for technical reasons, but because it seems like a reasonable approach. Multiples of 30 second cycles as suggested in the Sticky did not feel right to me [way too tedious] so i go with 60 seconds as outlined in my post above.

It is not a procedure that everyone agrees on, neither the procedure itself nor the need for it. So study the whole thread, listen to the opinions, and do what you think best.

[Beavis]

I ran 4 heat cycles yesterday, like Bruce said.

All four times I retorqued the heads and the last two times I retorqued the rocker boxes.

After the first cycle, I noticed I got more on the head bolts, about 1/4 turn, surprised the H out of me.

Before I take her out this morning, I have to re adjust the push rods.

Some say to torque it right the first time, I have multiple times and had a head gasket leak twice. Which leads to not only oil leaks but exhaust valve leaks on the head, fouling of the plug, loss of power, change in idle sound.......and a couple more I missed

[ryder rick]

I think the most important part of break in is to have the tune up right.

Most guys have a woody like a piece of heat treated hickory to hear their motor run.
They don't take the time to make things right before starting it.
A slobbery carb or worse one that is plugged up will wreck all that work and expense.
Incorrect ignition timing late or early will wreck it too.

It is very gratifying to take the time to make everything right and the bike starts with a couple kicks or one push of the button.

I do a couple of heat cycles on the lift, check for leaks and make any final adjustments (timing light). Then I do a short loop stopping at the gas station to top off with fresh fuel. Then if everything is cool I increase the size of the loops and exercise full power for short bursts gradually increasing duration while monitoring engine heat.

You want to use full power but not rev it very high and short duration to avoid making too much heat. This will press the rings firmly to the cylinder wall without making excessive heat and possibly butting the ring ends. If the rings get too hot they will expand and close up the end gap, if that occurs the "bad thing" happens. After the cylinder and rings break in the gap opens up some and the seal is better so there is much less hot gasses getting past the rings to heat them.

50 miles and change the oil & filter, I always cut open the filter to check for bad things.
Then 150 miles and change the oil again. Check the filter.
500 miles change oil again and if everything looks good you can go to normal service intervals. You will see fine particles suspended in the oil, this is normal. If you find anything large enough to settle or feel between your fingers it's time to take it apart and find the source. Bits of metal get imbedded in the piston skirts and drug up and down the cylinders ruining the bore and the motor will have a very short lifespan. Bits of debris in the bearings will quickly ravage the rollers and races creating even more debris and the destruction snowballs rapidly.

[MN Mailman]

So, it would appear the million dollar question is: since some say yes, others say no to heat cycles, is there any harm to doing them whether needed or not ?

[MN Mailman]

Originally Posted by ryder rick

I think the most important part of break in is to have the tune up right.

Most guys have a woody like a piece of heat treated hickory to hear their motor run.
They don't take the time to make things right before starting it.
A slobbery carb or worse one that is plugged up will wreck all that work and expense.
Incorrect ignition timing late or early will wreck it too.

It is very gratifying to take the time to make everything right and the bike starts with a couple kicks or one push of the button.

I do a couple of heat cycles on the lift, check for leaks and make any final adjustments (timing light). Then I do a short loop stopping at the gas station to top off with fresh fuel. Then if everything is cool I increase the size of the loops and exercise full power for short bursts gradually increasing duration while monitoring engine heat.

You want to use full power but not rev it very high and short duration to avoid making too much heat. This will press the rings firmly to the cylinder wall without making excessive heat and possibly butting the ring ends. If the rings get too hot they will expand and close up the end gap, if that occurs the "bad thing" happens. After the cylinder and rings break in the gap opens up some and the seal is better so there is much less hot gasses getting past the rings to heat them.

50 miles and change the oil & filter, I always cut open the filter to check for bad things.
Then 150 miles and change the oil again. Check the filter.
500 miles change oil again and if everything looks good you can go to normal service intervals. You will see fine particles suspended in the oil, this is normal. If you find anything large enough to settle or feel between your fingers it's time to take it apart and find the source. Bits of metal get imbedded in the piston skirts and drug up and down the cylinders ruining the bore and the motor will have a very short lifespan. Bits of debris in the bearings will quickly ravage the rollers and races creating even more debris and the destruction snowballs rapidly.

Rick, regarding getting ignition right, isn't it a bit of which came first, chicken or egg ?

I.e., can't tell how your ignition is without trying to start/running the engine, but if it's bad, don't try starting/running the engine ?
Or is static timing in play here.......

[Deimus]

Performing heat cycles on a newly assembled engine is all about protecting the new aluminum pistons. The problem is called micro welding. The cause is the extreme localized heat that can be generated by the new rings touching the freshly honed cylinders in the very few high spots that initially exist. At the pistons cycle up and down, the rings and cylinders effectively machine away these high spots generating lots of heat in the process. If too much heat is allowed to build up, areas of the piston ring lands can be melted off which will adhere to the rings. Once the piston ring lands are damaged, the pistons are forever compromised. You can find discussions about this from top performance engine builders if you do searches on the web.

[ryder rick]

Originally Posted by MN Mailman

Rick, regarding getting ignition right, isn't it a bit of which came first, chicken or egg ?

I.e., can't tell how your ignition is without trying to start/running the engine, but if it's bad, don't try starting/running the engine ?
Or is static timing in play here.......

Points can be completely static timed without a light.
Electronics with a status indicator you can get close enough to start and run on the first try.

[2007Low]

Originally Posted by Deimus

Performing heat cycles on a newly assembled engine is all about protecting the new aluminum pistons. The problem is called micro welding. The cause is the extreme localized heat that can be generated by the new rings touching the freshly honed cylinders in the very few high spots that initially exist. At the pistons cycle up and down, the rings and cylinders effectively machine away these high spots generating lots of heat in the process. If too much heat is allowed to build up, areas of the piston ring lands can be melted off which will adhere to the rings. Once the piston ring lands are damaged, the pistons are forever compromised. You can find discussions about this from top performance engine builders if you do searches on the web.

So with this in mind, what's your take on when and how long?