Why 2 cams?

9 replies to this topic
  • Math

Posted February 05, 2003 - 05:05 PM


I was discussing about mechanic with my buddy few days ago and we were asking ourselves:" Why 2 cams?"

We understand easily why the overhead cam, we understand why 4 valves or even 5 instead of 2 but why is it more efficient to put them under the control of different cams ???

Thank you

  • Superbike

Posted February 05, 2003 - 05:13 PM


It eliminates the need for rocker arms. It also keeps the valve angle straighter that it would be with one cam and a shim and bucket system. The key is it is simpiler. ---Mike

  • Math

Posted February 05, 2003 - 05:25 PM


Cool!! :)

Thanks again! :D

  • yamaha.dude

Posted February 05, 2003 - 06:00 PM


direct cam to valve contact allows them to rev so high, and to still be reliable... less to break, less to adjust, less weight to spin around...


  • Dwight_Rudder

Posted February 05, 2003 - 07:54 PM


It does allow more RPM but who needs that many R's on a dirtbike. DOHC is also much heavier than a SOHC. It also is much harder to adjust the valves although you don't have to quite as much.

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  • DesertChris

Posted February 06, 2003 - 01:12 PM


In addition to the reasons listed above there is also advantages with being able to make split lift/duration and timing between intake and exhaust that is not as easily done with a single cam.

  • beezer

Posted February 06, 2003 - 03:20 PM


Math, for all this good information we Americans are giving you please PM some profanity to use while I'm driving in Quebec.

I'll be up there next Fall and I don't want to go unarmed. :)

  • Math

Posted February 06, 2003 - 03:35 PM


Thanks to all of you for these explanations...

Hey Beez, Don't want you Americans to come here to blast us!!! :D :D

But man, are you crazy :D, why do you want to come in Québec in fall :D....You'd better buy yourself a good winter coat!! :D :D


  • beezer

Posted February 06, 2003 - 04:10 PM


I can handle it buddy, I've hunted in SK in December. :)

  • Dwight_Rudder

Posted February 06, 2003 - 08:24 PM


That is part of the RPM thing. I want the easier to maintain and lighter SOHC setup. I think somewhere down the road someone will come up with a good pushrod setup. Lower CG , Less head heat.


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