De-tuned BD 107"

[jhall]

In order to de-tune the 2003/4 Big Dog 107" motor I bought recently for the FXRD, I installed S&S bee-hive valve springs and 585 cam. The top end is nice and quiet, and it pulls plenty hard in the FXRD (FXR's version of a bagger). Looking at various dyno sheets though, it appears the 600 cam comes on much stronger, especially above 3000 RPM. But that is not where my motor spends most of its time, so will keep the 585.

Also installed manual S&S compression releases; they're OK but kinda wish I'd gone with the electric version. The folks at the local indy convinced me the electric versions often have problems though.

Also installed a Mikuni 45mm carb, which I'm still dialing in. Overall, it seems just a little lean. Ordering misc parts today to address that issue.

Wish my tired old body (56 next Tuesday) could stand up to a Big Dog bike. I have ridden a total of around 450,000 miles since 1975, and still average around 15,000 per year, but there is no way I could do that much on a hard tail, or without a fairing. Oh well, having a BD engine on a bagger is a nice compromise. Think I'll go for a ride

I appreciate all the tech info and fellowship available on this NG.

Joe H

 

[lee]

why did you want to detune the motor? Each to his own though so fair play to you. I think a 45 Mik might be too much carb for that motor.

 

[stlmikie]

Yeah, why the detune?

 

[dogvet]

Why detune a 107? Those engines had all the good shit and were quiet.
A 45 mm Mik carb will work just fine (you'll give up a little top end, but you'll make up for that in throttle response). I've got a 48 mm that I use with an S&S 631 cam (for those days when you just have to be different).:up:

 

[rhinoevans]

Also installed manual S&S compression releases; they're OK but kinda wish I'd gone with the electric version. The folks at the local indy convinced me the electric versions often have problems though.

Joe H

Is this true about the electrical compression? I am ready to order a set.