How much could one expect to gain out of a build like mine if I were to do the heads. That being said I would be going to a bigger throttle body. 50 or 58mm. HMMM how much could one bore the existing thottle body out, OR is it worth just getting a SE throttle body with bigger injectors. I know I dont need bigger injectors but would be nice to have when I step up to 107.
Or should I just wait to go 107 and just ride. Bike is fun. Did not get it dynoed yet.

 

Not really sure if a number can be given without knowing what you've got now. Proper ported head with larger valves will always add power. I would think a 55 throttle body would be all that you would need if you went to a 107 or larger later. I do have a question....Why didn't you just go to a 107 when it was completely apart? I don't remember how you initially gathered parts. You could have just as easily gone 117. The cases were split anyways, you put the money into the crank and a case bore isn't all that expensive. I would have on my 88" cases if I had to buy a crank when I went to a 107. Stayed all bore 107 instead

 

What are your numbers now?? Don't waste your money going from a 103 to a 107 ,its not worth the money.The difference is not much.What size throttle body you have now?? I think HPI takes a 50mm to a 54mm.If you already have a 58 they attach a piece to the rear, & open it up to a 62mm(if i'm not mistaken)check their website!! Bigger injectors work with bigger ci motors & more free flowing heads.You probably wouldnt need them on a 103.If your upgrading go as big as your pockets can afford.A 103 to a 107 is a waste of money !!! J.M.H.O.P

 

I have to believe that combo pushes off some good torque, but noses over about, say, 4600 ??
The ability to have that powerplant supplied with the proper airflow, is the true key.
Scott

 

Bike has some torque no problems there. Just would like to get the most out of what I have. What do you recamend as far as head goes and throttle body.
The bike pulls hard till the limiter wich is set at 6000. You can feel the cam come on at higher rpm but it is almost as if it has more there it just hasn't been found yet.

 

I went as far as my pockets could go at the time. Now that I have saved some money im thinking about improving what I have now.

 

we use alot of bigger TB`s,but it really depends on what your building,make sure to match the manifold size (intake runner)to the build & heads,we like around 1.6-1.65 for touring bikes & up to 1.800 for more WOT builds

 

If you don't know what your heads are flowing; you are pissing in the wind. Have the heads flowed before you do anything.

 

We have seen our new 107" R&R stage 3 builds go as high as 125 torque and horse with 100 foot pounds spool up at 2,500 rpm with a factory 58mm. I would expect a 103" to be close to 120/120.

 

A 103"er that grabs 120/120 is old news here, as a dyno in PA showed those numbers with a carbed 103", with our little Stage II heads several years ago.................after the bike had been ridden(better word "pi$$-pounded") for 4 years before it was tuned.
Jeremy, @ Bowling Green H-D, tuned 2 of our 107"s this past spring.
One with a little Wood 6 and our Stage III Head that went 115/120, and another with a T-Man .590, Stage III, that rolled off 120/121.
Pull 4/4 from those numbers and that'll be what to expect from the 103, or there abouts, with the 555, set up correctly.
Scott