2011-1200 Sportster Knocking

[outlaw76]

The situation:

I have a 2011 Sportster 1200. I let it idle for around 40 minutes on a 90 degree day. The battery was dead and I was trying to let it charge. The bike stalled and would not restart. Not sure if it overheated or what. I changed the oil and filter, there are no metallic flakes in the old oil and it was still feeling decent. Definitely dark but not burnt smelling. I use Castrol Syntec 20-50 full synthetic and that is all that has ever gone in the bike. Has 3500 miles. So I start it after changing the oil and it begins to knock from the front cylinder. It is intermittent though. After about 60-90 seconds it will begin to knock. Then it will stop and start, never steady knocking for more than 10 or 15 secinds

The question:

1. Would letting it idle overheat the engine and cause damage?

2. Since it is an intermittent knock instead of a steady knock wouldn't it more than likely be an lifter sticking?

3. Given the information provided what is the most likely cause of the knocking?

Thank You,

J. Padilla

 

[Jack Klarich]

You cannot let an air cooled Harley idle that long with out some problems. I would first run a compression test, if you are sure where the knock is from

 

[Breeze3at]

Could be many possibilities. My 1st thought is the piston expanded and seized to the cylinder. When it cools, it goes back to normal size, but there is aluminum on the cylinder walls, and the rings are stuck in the piston lands.

 

[Jack Klarich]

Could be many possibilities. My 1st thought is the piston expanded and seized to the cylinder. When it cools, it goes back to normal size, but there is aluminum on the cylinder walls, and the rings are stuck in the piston lands.

Broken piston skirt, bad bushing, collapsed lifter the list goes on, You need to tear the heads off after a compression test, and remove the cylinders to check the damage JMO

 

[SledDog]

What the other have mentioned is what you need to do for the knock issue. Even using a full syn, you may have thinned the oil enough to cause an issue.

Just for some info on battery charging. Just letting a bike idle after a jump start will not usually give you a good charge. It's better to ride it, or use a battery tender.