Hey Unbalanced,
What is wrong with the 211's ? My mechanic recommended the 211 's on these bikes. Said it would be a big improvement without sacraficing dependability. I still hadn't made up my mind until another friend showed me a brand new set still in the box that he is giving me for next to nothing.
I am going with the adjustable rods and am told if I want to change cams again I isn't that big a deal.
Your thoughts on that as well would be greatly apprieciated.
thanks [smiley=nixweiss.gif]
Nothing wrong with the 211 cams if I may be excused and jump in here. The single most important factors in cam selection are first : where do you want the power ..and second and equally improtant is : what compression does the cam need to perform properly.
A 204 or 211 cam in an 88" motor at 8.9:1 will behave differenty than in a 95" 9.6 :1 motor. Then head chamber design(squish) and valve and port size come into play. you cant compare a 211 cam in a 9.6:1 95" motor to the same cam in a 103 motor at 9.0:1.
We unfortunately have pretty sh**ty heads on our 103 CVO motors in that there is no "squish" to speak of to give some turbulance in the combustion chamber and the low comp. ratio of 9.0:1 limits us on cam selection. For good torque down low you want less than 240 Degrees duration and you want to close the intake valve at around 40 degrees abdc..to make up for the low compression by building higher cylinder pressure.
The 251 is basically a high lift version of the 211 if you look at the timing numbers...in fact the event numbers are different simply because of the difference in lift. The 211 is 23/45 intake ..59/17 exhaust at .508 lift the 251 is 18/46 intake ..56/14 exhaust at .579 lift. The 251 is called a Torque cam cause of the high lift/short duration...the valves arent open that long for less overlap and higher cylinder pressure but they open much further to try and fill the cylinder better. The 251 cam will be noisy cause of the steep ramps on the cam. your valve springs are "rated" to .575 lift and the 251 is at .579 ..but there is normally about 20 thou. fudge factor so you would be ok.
The 251 likes some compression though to work it's best and you dont have it...I dont like either cam as I feel if you are going in the cam chest..then get rid of the tensioners and go gear drive and be done with it. But of the two, the 211 will suit the motor better cause of the compression.