Overbored ports

2 replies to this topic
  • Terence

Posted December 08, 2000 - 02:18 PM


How will i know if my cylinder head has been over ported? I also re-aligned my valve pockets after it got jammed during an Enduro event. The whole bike feels so smooth, its almost torqueless. Please advise


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  • Boit

Posted December 08, 2000 - 03:52 PM


Are you talking about some Dr. Frankenstein mechanic going after your cylinder head with a Dremel tool? Many heads(and 2-stroke cylinders) have been destroyed by grind-happy apes going at it like the proverbial bull in a china shop. The results of "over" porting would probably radically change the velocity characteristics of the carburetor venturi. The flow characteristics of any 4-stroke competition machine are already well researched and developed. A competent porting person will strive to remain within those characteristics and strive to enhance the flow by cleaning up casting flaws and generally allow what's already there to flow with less restriction. Most use a flow bench to chart their results. As far as your valve pocket(s) problem, I'll pass on this one.

  • Taffy

Posted December 09, 2000 - 12:46 AM


if it's over ported you will hardly feel any difference. perhaps the slightest drop in torque, that's all.



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