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Last night I gave my thruxton a set of cams from a bonnie 790 motor. I swapped them straight across intake to intake, exhaust to exhaust rather than trying the 790 intake cam in the 865's exhaust which seems to be the hotter topic right now. I wanted to try that, but I'm not sure how to go about degreeing it in, I've only degreed cams in pushrod motors where I can put a dial guage on a lifter. Examining the cams side by side you can see that the lobes on the 790's are fatter (more duration)but the total lift is the same. This should mean an even easier job for the valvesprings, so no worries there. There's a drop in low end torque, most noticable at small throttle openings, but the increase in top end power is more dramatic. Nothing earth-shattering of course, but it pulls strong all the way to redline now. Front end waggles when quick shifting into 2nd & 3rd at 7K+. Previously I could never really determine which was better for accelerating from a freeway cruising speed, downshift & nail it or just open the throttle? No contest now, downshift. the power increases steadily rather than levelling off around 6K. If you're more responsible than me & never ask the bike to rev over 6K I'd keep the 865 cams for low end grunt. My bike has 39mm FCR's with pods and D&D cans, so I can't speak for gains on a stock bike, but I think it would give a similar positive result. Initial plug chops showed lean, so I went from 135 mains up to 138s. Looking better, just barely showing a hint of tan. I think 140s will likely be perfect, but I don't have any handy. Cheers!
[ This message was edited by: whatisit on 2006-08-14 07:54 ]
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Mr. Whatisit? That guy treats objects like women, man.
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