what is the importance in heat cycles

[weirboondocking]

I've always done at least 2 heat cycles to any new or rebuild motors but never formally looked up how to do it and if it relay does make a a motor last long.

so does anyone have any facts on the best method and any real proof that it helps.
imo it is a must but a few guys that ride with us just bought there first sleds and I don't want to give advice that is based on opinion instead of facts.

 

[diggerdown]

Heat cycles reduce stress on metal. It more or less expands and contracts them into their most dense form. Very important for long life of an engine. Some do it on a stand, others do it on short runs. With alumimum alloys it is even more important than any other metal. I cycle my engines at least four times before they go to work. Also makes a good way to make sure your coolant system is bled well.

 

[Schmeg]

This subject becomes a double edged sword when trying to heat cycle the unstable piston, and seat rings at the same time. When heat cycling, as stated already, the pistons become much more thermally stable and take a "set". Forged pistons much more so than cast. Forged pistons grow much more than cast hence the increased clearances required when fitting them to a bore. The problem lies in getting the rings to seat properly with the very limited time the cross hatch in the cylinders is effective. By putting pressure on the rings during the first hour of operation, you will get a good ring seal. But that is the time you don't want to be leaning on the motor too hard when heat cycling. So,,, when breaking in cast pistons, I warm the sled up thoroughly, then load the motor hard for short duty cycles on the snow. The same is usually done on a dyno. With forged pistons, I will heat cycle on a stand for 2 or 3 short idle periods up to when the heat exchangers get warm, cooling it off in between runs, then out on the lake it goes for short bursts after a good warm up. I can't over emphasis a good warm up. This is when the piston is "growing" into the bore. Too cool and you will squeak the motor for sure.

 

[aksnopro]

not a fan sorry, i usually get my sleds from the crate too, i have never blown a motor and i sold my 06 m7 with 2500, 08 m8 with 2700, and my 10 m with 1700, not one motor issue yet with a new sled i have purchased.

theres a lot of smarter then me people that say do it, but i just cringe when i see the temp light.....

does it actually say to do it on the cat setup paperwork? or is it just a common practice for some people?

-Aksnopro

 

[Schmeg]

With cast pistons (stock), heat cycling is a waste IMO. I just ruins the opportunity for good ring break in.

 

[killerrf]

i never heat cycled any of my sleds. except on my 09 m1. i was givin a cat directions for heat cycling by the dealer. i had 2600 miles on the m1 with no issues. this '13 800... i just gave it lots of WOT runs right from the start. we will see how it goes. belt didnt blow with no break in for it so thats a bonus. 175 miles on it now and no issues yet.

 

[Bacon]

Fire it up, warm it up good, and then ride the pi$$ out of it. Baby a new motor and you will have a turd on your hands. And not a polished turd either, just a stinky one.