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E: Engine Which camshaft for a comet?



everiman

Active Website User
VOC Member
#1
I need a new camshaft for my 1954 comet, my VOC spares choices are Mk I, Mk III MkIII NOS or 105 degrees (???), so which is best for around town, back road, gentle riding, or does it matter?
 

Glenliman

Well Known and Active Website User
VOC Member
#2
Phil Irving wrote a cam article for MPH back in the 80s?
I can't recall if it singled out the singles, it may have been mostly a discussion of cams for the twins. I think it is still worth a read.
The gist of it was that, with twins,MK1s are for touring, Mk11 s are for racing.


He was perplexed that so many people were installing his race cams on bikes used for two up touring etc. Not that the MK11s wouldn't work, he just saw it as a 3-4 k rpm detune that brought with it a bit of extra valve train stress. Most touring bikes spend about 99% of their lives below 4 k rpm.
Irving said the advantage of the MK2 was only at high rpm that most road bikes never see, or only see for a few seconds now and then.
When pulling up a long mountain grade at normal road speeds and sub 4k rpm, he said the MK1s had the advantage.


My understanding is that MK3s are MK1s with quietening ramps added.

Best to find the actual MPH article, I may have remembered it inaccurately.

Glen
 
Last edited:

everiman

Active Website User
VOC Member
#3
Phil Irving wrote a cam article for MPH back in the 80s?
----->
Best to find the actual MPH article, I may have remembered it inaccurately.

Glen
Having only been a VOC member for a year, old MPH articles are difficult. MK2 are not available from VOC unless what they call 105 are MK2?, whatever, if I wanted to go racing, I would get a two stroke Yamaha :)
 

davidd

Well Known and Active Website User
VOC Member
#5
Good advice. Mk1 is a nice cam. Easy to start and decent torque. The Mk2 requires engine mods, which is fine if you want to do mechanical work. It does not work well with a silencer. The 105 was the answer to getting Mk2 performance with a silencer.

The performance cams tend to be great 4000-6000. The Mk1s are very sweet from 3000, which is where most riding is done.

David
 


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