what are the characteristics of the 4S cam

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Same in my 920 but with twin VM34, Pete Lovell cylinder head.......nice bike , easy drive .
 
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It's interesting
In the past I have heard plenty of people say "you will never get a proper tickover with a 4s cam" and that they produce very little power down low etc
Maybe that's more true of the 750 fitted with a 4s?
 
baz said:
It's interesting
In the past I have heard plenty of people say "you will never get a proper tickover with a 4s cam" and that they produce very little power down low etc
Maybe that's more true of the 750 fitted with a 4s?
Click to expand...

What's the difference between the 2S used in every combat and the 4S....seems microscopic!
If you remove the silly bigger 4S ramps it would almost be identical to the 2S
At overlap the 2S is .150" and the 4S is LESS @,140"
what are the characteristics of the 4S cam

A prime example of why I try and verify what "people say" before I believe it.:cool:
 
dynodave said:
What's the difference between the 2S used in every combat and the 4S....seems microscopic!
If you remove the silly bigger 4S ramps it would almost be identical to the 2S
At overlap the 2S is .150" and the 4S is LESS @,140"
what are the characteristics of the 4S cam

A prime example of why I try and verify what "people say" before I believe it.:cool:
Click to expand...

But 4 is bigger than 2 so it HAS to be better! :p:rolleyes:
 
The 2S has more potential HP than the 4S. The 2s and the 4s have the same lobes. The only difference is that the 2S lobecenters are closer which means the 2S is a hotter cam. You just have to be more carefull about valve clash with the 2S. The "miniscule" difference you see in the lobe comparison is due to variation between brands and degradation of cam plates etc.

Look at the defect in the exhaust curve of the 4S - sloppy cam grinding.
 
Where the cam comes on strong is affected by the exhaust system. If you use a 2 into 1 with no back pressure, you can have pull from bottom, right up and through the top, with no bump. With separate pipes a restrictive mufflers, you will probably still get the surge of power at 4,500 RPM. It just means you ride the bike differently. If you ride in traffic a lot, a 2 into 1 exhaust might be better.
 
jseng1 said:
The 2S has more potential HP than the 4S. The 2s and the 4s have the same lobes. The only difference is that the 2S lobecenters are closer which means the 2S is a hotter cam. You just have to be more carefull about valve clash with the 2S. The "miniscule" difference you see in the lobe comparison is due to variation between brands and degradation of cam plates etc.

Look at the defect in the exhaust curve of the 4S - sloppy cam grinding.
Click to expand...

Thanks for that. I have a 2S I have been thinking of using in my 850.
 
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