evo ?
Road Warrior
Joined: Jul 2013
Posts: 1,476
Likes: 5
From: Florida
Concensus seems to be to let it warm at high idle until the rockers start getting warm to the touch. And no, it's not a myth, it allows the cylinders to expand and create a good seal. Others will have there own little ritual, but the above seems pretty popular. Thats how I do it, anyway
+1 on letting the engine idle to the rear rocker is warm, doesn't take long, about the time to put on jacket gloves and helmet and open my gate ....
Thrashing a cold engine of any type is not good.
Thrashing a cold engine of any type is not good.
Last edited by Kees; Mar 25, 2014 at 04:37 PM.
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
I would say its a myth....the original paper gaskets will leak eventually as they go hard and crumble...the James or Cometic gaskets shouldn't ever leak.
To say that the motor needs to be warm for the gaskets to seal does not take into account that if it was all loose when cold then the head gaskets would be blowing on start up.
To say that the motor needs to be warm for the gaskets to seal does not take into account that if it was all loose when cold then the head gaskets would be blowing on start up.
Seasoned HDF Member
Joined: Jan 2012
Posts: 15,395
Likes: 19,405
From: Upstate N.Y.-Rochester Area
I start my bike and let it fast idle while putting on my helmet etc., then I ease out of the driveway and take it easy for a few miles. Believe this is sufficient.
Road Warrior
Joined: Jul 2013
Posts: 1,476
Likes: 5
From: Florida
I would say its a myth....the original paper gaskets will leak eventually as they go hard and crumble...the James or Cometic gaskets shouldn't ever leak.
To say that the motor needs to be warm for the gaskets to seal does not take into account that if it was all loose when cold then the head gaskets would be blowing on start up.
To say that the motor needs to be warm for the gaskets to seal does not take into account that if it was all loose when cold then the head gaskets would be blowing on start up.
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Road Warrior
Joined: Mar 2007
Posts: 1,959
Likes: 2
From: Florida
Well, I guess running cold could kill my Harley before I die , but I doubt it. If it does, I'll fix it or sell it to one of you guys.
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Grand HDF Member
Joined: Mar 2007
Posts: 4,923
Likes: 266
From: Deep in the heart of New Jersey
My thought on the subject is, when the motor is cold all the parts contract slightly. When the motor is warming up, the parts expand or "grow" at different rates due to the thickness and type of metal used. When a motor is warming up, parts start to expand so when the motor is totally warmed up, all the parts and gaskets have expanded as much as they can and leaks are sealed. If you get in a habit of starting the bike ,taking off without any warm up, certain parts will expand faster then others and gaskets will tend to rip and therefore leaks begin. Valve covers are a classic leak point on Evos.,,
Road Warrior
Joined: Apr 2007
Posts: 1,952
Likes: 15
From: Senoia, Ga., by way of Miami, Fl..
No better way to create heat than to drive it down the road.. However, with that being said, aluminum engines have a tendency to change quite a bit when heat cycled. While the head bolts were almost certainly installed and torqued cold, the expansion and contraction of the engine from stone cold to normal operating temp, would cause substantial growth.. From memory, I seem to recall hearing +.010".. I always warm before riding off, if I must just hop on and go, I'm easy on it till it gets hot.. More heat, more clamping force on the gaskets, good enough for me... By the way, my James gaskets are leaking, only cold, on my Dyna since about 5k...