Bulletproof 117" build for the Breakout

Reply Subscribe

Thread Tools

Search this Thread

Oct 19, 2017 | 09:15 AM

#51

djl

HDF Community Team

Joined: Jun 2006

Posts: 12,776

Likes: 2,607

From: san antonio

Quote:

Originally Posted by donk_316

Don't let the internet be your main decision maker though... I remember all the sky is falling posts from 2007-2009 about how the cranks will scissor and so on. I don't know of a single person who had their twin cam crank blow up. Remember HD sells a **** ton of bikes and these forums have a couple thousand members? and a handful of them swear the cranks are bad? Cmon.

My personal 96" had 20,000+ on it with zero issues. Went to a FM 107". 3 years later and another owner. Still no issues. I beat the CRAP out of that engine because I had the big warranty. I believed all the stories about the crank and thought the engine would surely let go and I could get a fresh engine under warranty. Never happened. So try and keep it real by riding your bike and not believing everything you read. You see it on every single forum for everything with wheels. Also, the people who scream the loudest about bad cranks also want to sell you something...

You have to break that "**** ton" of bikes down to those that run modified motors and those that don't. A stock motor is not nearly as likely to tweak a crank as a modified motor but there were an inordinately larger number of '07 OEM motors with shifted cranks than in previous years. Remember, '07 was the year the MoCo changed the crank run out spec for warranty purposes from .003" to .012" and the crank manufacture shifted off shore. Think the MoCo might have anticipated a few tweaked cranks?

Now take that group of modified motors and while I don't have an empirical data to back this up, certainly you will find a higher percentage of tweaked cranks in that motor group. Does that mean the sky is falling, not hardly but IMHO, if you spend $20K on a motorcycle, you should expect the heart of the motor to hold up even under some mild modifications. In m own experience, I have been running a garden variety 95" motor (104TQ/96HP) in a 2005 FXSTD for the last 25K miles. Just decided to re-configure the motor to a 98" motor with different components with 110/115 numbers in mind. When I built the 95" motor, crank run out was .0025", good for my gear drive cams. However and to my dismay, when I tore the motor down for the rebuild, I found crank run out was now .0045", a scored cam plate and oil pump. I ride the bike a fast as I can given road conditions but I do not "beat" on the bike; no burn outs, no attempted wheelies, etc., so a lower unit rebuild was not in my plans.

So, think what you want but if one is building up a motor the is hunting numbers in the 110/120 range and doesn't want to risk wasting that money if/when the crank goes south, address the bottom end as part of the build plan. JMHO.