wheezy_e

A couple days ago I started watching the new triumph forums again. I'd not kept an eye on them for a while since I've been busy with other bikes. Lord only knows why, but when triumph built the thruxton (billed as a higher performance bonneville) their "revised cam profiles" were actually less performance oriented than the previous bonnie peices. Not too surprising since their claim of "higher compression" (they dropped the claim after the initial 04 model) turned out to be bogus, just like their bigger carbs were exactly the same peices with different needles & jetting. Regardless, a while back I bought a wrecked bonnie to eventually build another motor for the thruxton with. I went ahead & swapped the bonnie's cams into the thruxton to see what would happen. VERY good results. Some decrease in low end grunt, most noticable at lesser throttle openings, which rarely happens with me anyhow. Power used to level off at 6K, I could never really determine if when cruising at 5K or so RPM, it was better to downshift & nail it or just stay in gear and open the throttle. I suspected the latter each time I tried the former. No contest now, power builds steadily all the way to redline. Front end gets light & wiggles when quick shifting into 2nd & 3rd from 7Kish. Very pleasing. Initial plug chops showed lean, so I went up from 135 mains to 138s. Power seemed to increase again & plugs are just barely showing a hint of tan. I'll try some 140s next, but they'll probably be overkill. Here's the cam numbers. They're unverified, but I did measure the total lift with a dial caliper, identical. Looking at the two sets side by side you can see the bonnie peices have fatter lobes. Pretty scientific, huh? Or as my cousin likes to say "Trust me, I have a scientific feeling about this."

Thrux 865 Intake-------------Bonnie 790 Intake
lift .374"------------------------.374"
IO 4*BTDC---------------------19*BTDC (@ 1.0mm lift)
IC 48*ABDC-------------------43*ABDC (@ 1.0mm lift)
Duration 232*-----------------Duration 242*

Thrux 865 exhaust-----------Bonnie 790 exhaust
lift .370"-----------------------.370"
EO 33*BBDC------------------36*BBDC (@ 1.0mm lift)
EC 7*ATDC--------------------20*ATDC (@ 1.0mm lift)
Duration 220*-----------------Duration 236*