Hi All,
Needed some input from the pros on here. I have a 2009 Street Bob and upgrading from 103 kit to 110 kit. I already have woods tw 8-6 cams in my bike and setting compression at 10.75. My heads already worked , ported etc. Regarding TB, I spoke with someone at Fuel Moto and they suggested for this setup I get a SE 58mm with 5.3 g/ps fuel injectors. Others says may be too much? I was also thinking of the HPI 55mm and updated injectors. Any thoughts would be appreciated.

 

 

I did the 5.3 injectors on my FM 107 777
so far its good

 

Most likely, a SE 50mm will be adequate. I'm told they're good till 120HP. You can get a complete 50mm SE throttle body with 4.9 injectors for $350.00 at Boardtracker HD.
This is way cheaper than HPI..

 

Be aware that the 58 has a 1.750" intake port I.D.
If your heads do not match that dimension, you'll sure want them to.
Scott

 

I would also look into boring yours out. With said compression. What is the realistic HP number you are looking at achieving. Are you willing to give up tq for that, or are you looking to error on the side of tq?

 

What does it take to get the heads to match the 1.750" intake? Would it be costly?

What is the size of the intake on stock heads?

 

Im looking to increase both hp & tq but more tq is what Im looking to achieve.

 

This is pretty much the answer. Would I maybe spring for the 55 or 58? Sure. My 107" great heads stops at guess what....120HP. The tuner who knows his chit said you could go bigger, but you'd gain a tiny fraction under the curve and a 5-8 HP at peak. So, other than dyno sheet bragging, I wouldn't know the difference.

 

If you are mainly chasing torque, 55mm tb and 4.9 injectors would be all you need.


suffice.