06 Ultra 113" All SE except gear driven cam

Bike runs great but was making a hell of a noise. Local dealer/builder finally pulled the heads and discovered the pistons are hitting the heads. They are barely touching as there is no damage to either pistons or heads. The indication this was happening is there were no carbon deposits where they came in contact. The contact is on the outer edge of only one side of each piston. Any ideas what would cause this. Harley seems to be perplexed. The dealer thinks the pistons and rods are growing faster than the heads when it heats up. But the symptoms occur even when the bike is cool. Any thoughts would be appreciated and I can provide more build details if needed.

 

Sounds like the wrong head gaskets were installed.

 

As I read your post I thought "probably wrong head gasket"... then went to post and see Grover said that. It is amazing what a few thousanths makes on a high compression hig hp motor. On a small block v-8 it usuall the valves they are hitting due to the LONGER DURATION of the higher performace cam...

Hogback

 

Engines usually have a tolerance called "Deck Height", which is measured with a depth michrometer from the top of the cylinder wall to the top of the piston at TDC.Some engines require a 'standard' to use as a base if the piston is designed to come out of the bore at TDC.

Should be a no-brainer for the dealer unless they don't do overhauls. If the deck height is wrong, then either the base is machined wrong or the pistons need to be machined for proper clearance and rebalanced.

I'm no expert on Harley engines by any stretch of the imagination, but I have built engines of all sorts, from motorcycles to autos to aircraft over nearly 40 years... I can't imagine that the clearances are so close that this could happen without something being pretty obvious to to the trained HD engine technician.

 

Soundsto me like the wrong pistions are in the motor the longer stroke requires a pistion with a relocated wrist pin in order to prevent this the deck height spoken of by ZD is almost 0.0 in a stock twin cam so what they actually need to look for is the top of tha pistion sticking out of the cylinder at all normal harley head gaskets are .040 thick and most of my engines the edge of the pistion is flush with the top of the cylinder (deck height 0.0)so it issomething seen with the necked eyeyou check it because alot of stealers try to cover up try F*** ups

 

Someone didn't check clearances, lot of factors to be considered, the most important is heat expansion, (rods get longer under heat) it may not be much but it has to be considered in HC engines.. When I built my 496 BB Chevy went through all of this..
But, if you run both pistons to TDC and measure, give room for HE, your good to go..

There no Replacement for Displacement...

 

Most "service techs" are not true engine builders. They go to Harley Tech and are taught how to repair Harleys. However after working at a dealership doing mostly parts replacement, they tend to lose some mechanical ability. They forget to check part numbers and clearances. You wouldn't believe some of the stuff we have seen over the years. Now in closing I want to say that not all Service techs fit this description.

 

(rods get longer under heat)

This is my exact thought, making itall the more important to check clearance tollerances.

 

+1

 

Provide the build details; also, any pics would be great.