Does changing from stock to bigger throttle body help?

 

I have heard it isnt worth doing on a 103. You might get some different opinions.

I can tell you that your air cleaner choices are limited when you go to 58mm..

 

I would call Gerolomy, do a google.

 

There are 2 things that bigger is not always better................intakes and exhausts.

But with that being said, depending on your build.......you could benefit from a slightly larger throttle body. HPI sells bored out TB's for $200 with exchange, Dakota Kid does them as well, and Hillside Cycle also bores out stock TB's. There are others as well that offer this service, or you can buy a complete new TB from HPI or Zippers for a lot more money.

Steve

 

What build and what throttle body? As PhilM says, think of the garden hose and fire hose comparison. Your bike needs high velocity air through the throttle body (the garden hose) to promote cylinder fill (and on carb'ed bikes to atomize the fuel), rather than just more air moving slower(the fire hose). Also, fuel injectors play a part in this since they are rated as to how much fuel they can deliver. On large displacement or very high performance builds, the fuel injectors may need to be changed out for injectors that can deliver more fuel than the OEM injectors. Larger throttle bodies may help top end performance at high rpms when air flow is at a maximum, but hurt lower rpm throttle response when less air is moving through it.

 

This a 103 with 10.5 compression, ported stock heads, stock throttle body, sert, se heavy breather, S&S 585 gear drive cams, and D&D boss 2 to 1.

 

Well said Carl!

esram ~ on your config, (espically that 09) the stock TB is more than adequate. As Carl mentioned, you "might" get very slightly higher PEAK numbers (a condition that you almost NEVER see on the street), but they will come at the cost of some bottom end.

You'll see better return on $$ from a killer tune than a mammoth TB.

 

Thanks everyone for your advise.