low end and top end cams

[hardcoreclown33]

hi guys i just bought a 400ex and it has a low-end cam in it and my friends has a mid-top-end cam i was wondering what makes a low-end cam and what makes a top-end and will the low end cam efect my top end at all thanx for any info u can give to me

[Wheelie]

The biggest factor in the RPM range of a cam is the Duration, or the amount of time the valve stays open. A top end cam will have a longer duration--the valve stay open longer--, a low end cam will have shorter duration. Usually, a cam with more duration will have more lift (the amount the valve opens)--not a definite rule of thumb, just a trait that is commonly seen.

If you want a cam to perform in the top end of the RPM range, low end will be sacrificed, and vice versa.

Hope that helps.....