Last sumer I had a strange vibration in my bottom end that under the right conditions would travel from my seat all the way up into the bars. It wasn't heavy or audible. I had suspected a wrist pin bushing. Unfortunately I was correct. This led me down the rabbit trail to the discovery how flawed the 07+ twin cam bottom end is. I am not good with making DIY threads but I have plenty of pics to show. I have limited space at home. Basically a 10x14 woodshed. Once the motor was out I took it to work and tore into it after hours. Not 1 HD specialty tool was used in the making of this motor. No bike lift or table. One reason for this thread was to take some of the mystery out of the Twin cam bottom end. They are pretty simple and if you take the time it can be done. I did go over board on the internal components and to save money OEM parts can be used for this build. I hope this thread serves to help others tear into their engine. Plenty of forum members helped me along the way.

This is my initial thread when I was figuring all this stuff out and the members that gave their 2 cents: https://www.hdforums.com/forum/gener...2007-fxst.html

Here is the bike entering the woodshed for teardown.

 

Here is the vibration I felt.







See the little nick in the piston where the turned bushing was making contact with the piston.

 

I then went on a search for a replacement bushing only to find out that a $20 bushing is not serviceable and the crank needs to be replaced or serviced by a crank shop. In the end I chose Darkhorse for reasons to be explained later.

 

Here is a look at my tensioner with 28k on them. I dont know why they are chewed up but I suspect a pump going bad is to blame. The crank had .004 run out. While this is acceptable in the long run it will eat up the oil pump and brass bushing in the cam plate.

 

Then after inspecting my parts I found a tell tale carbon trace in the head. If you know what you are looking at you start crossing your fingers.





Yep its cracked!

 

At this point this motor goes to the shop and I start taking the buss.

 

Now I begin splitting the cases and explore my options for parts and start selling stuff on ebay and craigslist.

 

She is split. A little effort with the rubber mallet and its appart. At this point i'm not concerned with cleanliness or damaged seals or bearings as all will be replaced. One pic I never took was all the little baggies full of bolts and a sharpie indicating where they go.





Careful machined parts are sharp!

 

Next was removing the balancer assy. I did have to make a tool using scrap steel laying around the shop.



Also you need to line up the locking pin holes to prevent rotation as you pull them.

 

Next was pulling the blind bearings. They were going bad also.







The balancer guides were only 20% worn but were brittle and were being replaced.