TRIUMPH TWIN POWER Bored & Flowed Throttle Bodies

I have 08 America, did big bore kit (904) last year. While the engine was apart I ported the cylinder head, inlets are especially poor! I put the inlet manifolds on the head and aligned/ported them too. I did the port work myself, cost me an air powered di

 

Cost me an air powered die grinder.

 

I would do it whilst doing further engine work,as doing it on it's own wouldn't be worth the minimal gains to be had from std bore compression ratio and cams, I stayed with std cams but did everything else. Std HP on std motor is quoted as 61 HP @crankshaft. When I dyno'd my bike new it was measured @ 53 HP @ rear wheel, after tuning lifted to 57.3 HP now have 904cc high compression big bore from wiseco I have gained about 15 more ponies but torque has jumped considerably. As I tow a camper here in Australia I can assure you the torque gain is very noticeable. Picture is swmbo and my good self @ the start of our 2009 run to Phillip island, its the smaller of my two trailers. the exhaust ports were just cleaned up a bit, But the Inlets I took quite a bit out of the Bottoms to curve the port more smoothly to the Valve opening's, the inlet manifolds I opened up to match the inlet openings in the head, there was a small step ! about 1/2 a mm to 1 mm high.

 

Hi Marc,
Did you go ahead and port and flow the throttle bodies ? Hate it when threads are dropped/forgotten, as it might be something I should look to doing for more torque , as I tow it would be good to know what gains you made and how much more work you did to get it.
I have totally gutted out SAI, oxygen sensors, air box opened out top and bottom with baffles removed. Getting in the vicinity of 75 to 80 ponies.

Cheers Mick (capt).

 

Hi Half Ton,
Pity we would all like to know the benefits to be gained from throttle body boring, the lower pictures in my post above, are left hand cylinder exhaust and inlet then right hand side, 5th is one of the inlet manifolds. The inlets changed considerable, you couldn't see below the base of the valve stem , where it meets the valve head, much more of the valve head is visible, as the material in the way was removed. The bike pulls much harder and further up the rev range.engine sounds deeper @ lower rpms and changes in note to much higher pitch above 6,000 rpms, this is possibly the inlet making more louder noise than the exhausts.