Questions about putting a different motor in my bike

Discussion in 'General Harley Davidson Topic' started by GimmeFuel, Feb 19, 2011.

  1. GimmeFuel

    GimmeFuel Member

    I've got a 2004 fatbody and I have a few questions about installing a larger engine and the potential problems I might encounter.

    1) Is there enough room with my frame for a 120 ci crate motor? If not, what is the largest crate motor that frame will accomodate?

    2) What are some problems that I might encounter by making such an upgrade and how should they be dealt with?
  2. karlsbike

    karlsbike Active Member

    Someone who's done it will post details. But for Evo engines, there is a pile of different manufacturers, and they all specify installed height vs. stock which is the critical thing for these. If you're thinking about the SE120R engine, I see it's specifed for 2007-up ST meaning the mounts may be different on yours?

    But, what many forget when they boost their engines is to balance the rest. So, to answer your no.2:
    You've got a single-caliper front brake (forget the rear, it's good enough...). Upgrade it to Brembo, or at least make sure what you've got is 100% good. Install s/s lines, get some sticky pads, possibly new rotor, etc. I'd look at installing double brakes up front.
    A stock driveline in good condition will probably be ok, but whatever is a bit worn now will start failing - clutch, tranny, primary, etc...
    Installing a 120 cuin engine will double your HP, and that can take it's toll
  3. The4opps1

    The4opps1 Junior Member

    Karlsbike brings up some interesting facts to consider when changing engines. Basically, as with any cusomizing project, you can do just about anything, if you have the money. Whether it's worth it is another story. Reminds me of a buddy I grew up with who as a student at Newark College of Engineering (now NJ Institute of Technology) stuffed a 327 Chevy into his TR-3. The radiator was in the trunk, and it was that part of the project that was his thesis:"How do you cool off a big engine with a remote radiator". Was it cool? OOOOOOOOOOOh yeah. Was it fast? OOOOOOOh yeah. But in the end, by the time he switched out the rear, had a drive shaft made, reinforced the frame, etc., etc., it wasn't worth it. Aside from getting an A in his senior thesis, the project was a bust. The little Triumph just wasn't built to take that much HP, and for obvious reasons, wouldn't corner worth a darn. I'm not saying don't do it, but try to do as much research as possible before making the committment..
  4. dbmg

    dbmg Experienced Member

    As the other posts have recommended, how deep is the bank account to do it correctly? For not done correctly there could be catastrophic results. And then there is the thought of selling bike, and if not done 100% what value would the bike have???? Just something to think about...

    BUBBIE Well-Known Member


    My opinion would be Work With What You Have..

    You can build a big enough engine from the TC in the 04 fatboy... It will NEED NO modification outside the motor for ITS fit.......

    My Way..

  6. Jack Klarich

    Jack Klarich Expert Member