ET: Engine (Twin) Cams
- Thread starter rapide049
- Start date
you dont i understand?
The timing of both is supposed to be identical so there should be no difference in performance but I have measured a large number of cams and have yet to see a quieting ramp on what is supposed to be a Mk III. I cannot say that none of them have ramps but when one measures the lift, takes differences and computes velocity and acceleration, the ramps just do not show up.
I have 2 Twins
The Mk1 will pull on the Hills , The Mk3 I will be back into 3rd gear
the MK3 runs nice but does Not have the same pulling power
Mk1 has Standard Mag and 30mm Mk 11/2 concentrics
Mk3 has BTH Mag and Mk1 30mm Concentrics -(and uses up to 2 litres of less Fuel on a Tank
The Mk 3 is much quiter in the Timing Chest
Hope this makes Sense
Thanks Greg
The Mk1 will pull on the Hills , The Mk3 I will be back into 3rd gear
the MK3 runs nice but does Not have the same pulling power
Mk1 has Standard Mag and 30mm Mk 11/2 concentrics
Mk3 has BTH Mag and Mk1 30mm Concentrics -(and uses up to 2 litres of less Fuel on a Tank
The Mk 3 is much quiter in the Timing Chest
Hope this makes Sense
Thanks Greg
Interesting....
I've ridden bikes that go strong and yet on inspection have worn out cams and followers.
I'd be really surprised if the cam profiles between mk1 and Mike coulton felt via a seat of the pants test.
Could the difference you experience be down to other factors aside from cam profile, such as carburation, compression, bore wear, valve seating, etc. ...?
When I rebuilt my Rapide back in 2016, I had always felt the bike was missing something........it went ok, but the engine felt like it had no real "Life in it"......After the strip down I was surprised to find the pistons were 8:1 compression.........I had always thought it was about 5:1 the way it behaved.........Anyway the cams were original Mk 3's as Greg is asking about.......These were in perfect condition.......During the rebuild, I had what appeared to be some sort of Mk 2 cams, and a set of the highly polished followers that Big Sid sold me. These cams have actually got way more duration than normal Mk 2's, but i used them anyway, and replaced the pistons with new ones again at 8:1 comp........Now the bike goes like a " Raped Ape" so that's good enough for me. To me it is almost like the Mk 3 cams were retarded, certainly not lack of compression like I had always thought.......
Both are in Top condition , the only difference between them as I have explained
Greg that is good discription ,it goes ok and everything is New in it , yes it Feels Retarded - thanks for your reply
Greg, Neal's new Mk 1 cams work well........I believe they are copies of the factory originals, but the bikes seem to go quite well with them installed, and I haven't noticed the timing chest to be overly noisy either. Cheers for now........ Greg.
Do both bikes have the same type of silencer?
The silencer design can make a big difference to power output.
Glen