Head Re-torque Following Rebuild or Motoman's Break-In Procedure?

[Guest]

Hi!

While reading Motoman's Break-In procedures at http://www.mototuneusa.com/break_in_secrets.htm I kept thinking of the head gasket that needs to be retorqued at least a few times between heat cycles (run the bike stationary until it reaches normal operating temp, allow to cool overnight and retorque, etc).
Motoman does not seem to be doing the head gasket retorque, etc.

What would you do/recommend for a newly rebuilt engine?

Thanks!

 

[niclpnut]

Hi!

While reading Motoman's Break-In procedures at http://www.mototuneusa.com/break_in_secrets.htm I kept thinking of the head gasket that needs to be retorqued at least a few times between heat cycles (run the bike stationary until it reaches normal operating temp, allow to cool overnight and retorque, etc).
Motoman does not seem to be doing the head gasket retorque, etc.

What would you do/recommend for a newly rebuilt engine?

Thanks!

From the web site:

Many readers have e-mailed to ask about the cool down, and if it
means "heat cycling" the engine.

No, the above "cool down" instructions only apply if you are using a dyno machine to break in your engine. The reason for cool down on a dyno has nothing to do with
"Heat Cycles" !!!

Cool Down on a dyno is important since the cooling fans used at most dyno facilities are too small to equal the amount of air coming into the radiator at actual riding speeds. On a dyno, the water temperature will become high enough to cause it to boil out of the radiator after
about 4 dyno runs. This will happen to a brand new engine just as it will
happen to a very old engine.

(Always allow the engine to cool down after 3 runs whenever you use a dyno.)

If you're breaking your engine in on the street or racetrack, the high speed incoming air will keep the engine temperature in the normal range.
(In other words, you don't have to stop by the side of the road to let your bike cool down.)

What about "heat cycling" the engine ??
There is no need to "heat cycle" a new engine. The term "heat cycle" comes from the idea that the new engine components are being "heat treated" as the engine is run. Heat treating the metal parts is a very different process, and it's already done at the factory before the engines are assembled. The temperatures required for heat treating are much higher than an engine will ever reach during operation.

The idea of breaking the engine in using "heat cycles" is a myth that came from the misunderstanding of the concept of "heat treating".
eat treated" as the engine is run. Heat treating the metal parts is a very different process, and it's already done at the factory before the engines are assembled. The temperatures required for heat treating are much higher than an engine will ever reach during operation.





I've used his break in method on the street and at the 200 mile mark, I went in and checked valve clearances and re-torqued the head at that time.

Nic

 

[SqDancerLynn1]

It is mandatory if you have an old English bike !! Yes I would do it...

 

[trippivot]

Like he said it is a touchy subject...There are MANY DIFFERENT CORRECT ways to get a engine to seat in quickly.

My deal with the final head torque value is to get 3 or 4 full heat-up/cool-down cycles before I re torque the head and check valve lash.

It is boring but you have to get everything hot and cold to expand/contract them into the natural shape they will settle to under proper torque pressure. Because it is like a big sandwhich I will Re-torque only once unless there is a compression leaking problem. Putting a head down on an engine is a 1 way deal for me I don't like to loosen and re-torque.

If you got a oil leak, take the head off find out why and totally start over. (or just wipe the engine off more often)

 

[Guest]

My deal with the final head torque value is to get 3 or 4 full heat-up/cool-down cycles before I re torque the head and check valve lash.

Do you do these heat/cool cycles with the bike stationary ... or after breaking it in on the road in a similar fashion as Motoman does?
Thanks!

 

[49er]

As Trippivot says, there are many right ways of doing it.

I use Motorman's running in procedure. With MLS head gaskets, theoretically you don't need to re-torque. However, its a different story when not using a MLS base gasket. For that reason, I re-torque after 4 heat cycles.

Prior to torquing the head down, it's important to make sure that the stud threads and their mating head surfaces are sound and clean. Lubricate the treads, nuts, and the friction surfaces of the washers before assembly. When using MLS gaskets, don't over torque. All you do is reduce the effectiveness of the multi layer system and risk bore distortion, especially when the engine has been drastically over bored.

Be particular about following the correct torquing sequence, always working from the center of the head outwards. Start with low torque values and progress to the final torque figure. Never use an angle drive adapter when access is limited. This will add more friction and produce an under torqued nut. I discovered this when re-torquing my last engine using a straight drive off the torque wrench. The angle doesn't need to deviate far from a right angle to increase drag/friction.

Before re-torquing, follow the sequence and back off each nut about 1/2 a turn. Loosen and re-torque one nut at a time, as you don't want to unsettle the seal surfaces. This eliminates the possiblility of thread bind which causes a false reading of torque values.

Don't complete your heat cycles stationary. You will miss the opportunity to bed the rings in early under acel/decel conditions, which is the very point of using Motorman's procedure.

 

[Guest]

As Trippivot says, there are many right ways of doing it.

I use Motorman's running in procedure. With MLS head gaskets, theoretically you don't need to re-torque. However, its a different story when not using a MLS base gasket. For that reason, I re-torque after 4 heat cycles.

I'll be using a Cometics graphite head gasket along with a Cometics copper base gasket. How would you handle this gasket combination (torque/heat cycles)?

Prior to torquing the head down, it's important to make sure that the stud threads and their mating head surfaces are sound and clean. Lubricate the treads, nuts, and the friction surfaces of the washers before assembly. When using MLS gaskets, don't over torque. All you do is reduce the effectiveness of the multi layer system and risk bore distortion, especially when the engine has been drastically over bored.

Be particular about following the correct torquing sequence, always working from the center of the head outwards. Start with low torque values and progress to the final torque figure. Never use an angle drive adapter when access is limited. This will add more friction and produce an under torqued nut. I discovered this when re-torquing my last engine using a straight drive off the torque wrench. The angle doesn't need to deviate far from a right angle to increase drag/friction.

Before re-torquing, follow the sequence and back off each nut about 1/2 a turn. Loosen and re-torque one nut at a time, as you don't want to unsettle the seal surfaces. This eliminates the possiblility of thread bind which causes a false reading of torque values.

Got it! Thanks!

Don't complete your heat cycles stationary. You will miss the opportunity to bed the rings in early under acel/decel conditions, which is the very point of using Motorman's procedure.

Are you saying "not to do any heat cycles stationary"? In other words, to get on the road right away to bed in the rings?

Thank you!

 

[Nessism]

Yes, ride the bike. Briskly, with lots of throttle usage. Good for the rings. Stationary running is not recommended unless you have a big fan in front of the engine, and only if you are breaking in an aftermarket high lift cam or similar. Torque the head and check the valves after a few good heat cycles. Change the oil too. I torque the cylinder head on my bike every few hundred miles until it settles down and the torque fall-off stops.

 

[Guest]

Yes, ride the bike. Briskly, with lots of throttle usage. Good for the rings. Stationary running is not recommended unless you have a big fan in front of the engine, and only if you are breaking in an aftermarket high lift cam or similar. Torque the head and check the valves after a few good heat cycles. Change the oil too. I torque the cylinder head on my bike every few hundred miles until it settles down and the torque fall-off stops.

Thank you!

 

[49er]

I'll be using a Cometics graphite head gasket along with a Cometics copper base gasket. How would you handle this gasket combination (torque/heat cycles)?

What I meant was that if I had MLS gaskets top and bottom of the cylinders, I would only do one torque. I do a re-torque only because the stock base gasket will settle with heat cycles.

Why have you fitted a copper base gasket? Copper hardens when heated, unless you quench it in water from red heat. Do Cometic offer a coated copper base gasket?

 

[Guest]

Why have you fitted a copper base gasket? Copper hardens when heated, unless you quench it in water from red heat.

To obtain proper cylinder deck height.

Do Cometic offer a coated copper base gasket?

I don't know. It will be coated with Gasgasinch.

 

[Suzuki_Don]

Yes, ride the bike. Briskly, with lots of throttle usage. Good for the rings. Stationary running is not recommended unless you have a big fan in front of the engine, and only if you are breaking in an aftermarket high lift cam or similar. Torque the head and check the valves after a few good heat cycles. Change the oil too. I torque the cylinder head on my bike every few hundred miles until it settles down and the torque fall-off stops.

Ed, just curious how you tell when there is torque fall off. As there is a need to back each nut off by 1/2 a turn to break the thread lock before tightening to the correct torque again, how can you tell if the nut was still tight enough or needed to be tightened again.