Cams! How they work!

[ATV_MAN]

Ok i was just wondering about cams.If i got a bottom end cam i know it would increse bottom end more than a stock because its a bottom end cam. But would that mean it would have less top end then a stock cam and vice versa(top end cam,loose stock bottom end?).

Ok I will ttry to help you to undrstand how a cam effects the powerband but I know there are others here who could offer more.

First you need to remember that what a cam does is open and close the valves, and different cams will do this differently.

A cam is measured many ways including lift and duration on both the intake and exhaust valves. There are other things that will effect how a cam works but to keep it simple just think of these two for now.

Lift is how high the cam will push open the valve which creates a certain size opening for the air fuel mix to enter the combustion chamber.

Duration is the length of time the valve stays open.

In keeping it simple what you need to think of is having a larger lift (bigger opening) and a shorter duration (time its open) would tend to produce more bottom end to mid end than top end increases due to the shorter opening time combined with the larger opening. The oposite would be smaller or same lift but with longer duration (allowing the valve more open time at higher rpm) would tend to produce more increase in the mid to top end.

I hope this helps as cams can get pretty complicated. You should also consider how you use your quad before specin out a cam.

[ATV_MAN]

Ya i understand how they work i just wannna know if I get like a bottom end cam would it decrease top end over a stock cam?

[JabberJaw]

I purchased the xr400 cam, as it was know to work. Also I had the flywheel lightened. I seem to have power in bottom, mid, and top end. I took it out yesterday with my wife riding double, going up the steep road where I usually shifted to 3rd, I now was doing in 5th gear with two people on.

I also had installed a 14 tooth sprocket because ridng in the woods I had to pull the clutch in to make sharp turns or it would bog out or even stall. I tried it with my wife on the bike and was amazed that 2nd gear did not even bog out. I could almost come to a complete stop, then gas it, and have power...

If you buy a cam, no matter what type, I would suggest getting the flywheel lightened.. I don't know a lot of technical advise about engines, but I LOVE MY BIKE NOW!!!

[250xman]

no it shouldnt. accually i think it increases the power throughout the powerband but not much on the top but noticable on a dyno. you wouldnt really feel it on the bike when your riding it.

[JabberJaw]

So, basically the top end is either coming from the cam I used, or the bigger piston, or a combo of the whole works?

Ya i understand how they work i just wannna know if I get like a bottom end cam would it decrease top end over a stock cam?

Not to be nasty but then why didnt you say that the first time. I lost a lot of skin typin that crap:)

Plus if you know how they work you should be able to answer that question yourself:rolleyes:

Good luck

[ATV_MAN]

Thats what i did ask in the first place!!I know how they work but i still dont have my answer yet no one has answered it yet.

[Nate]

a stock 400ex doesn't have a very strong top end to begin with, so i don't think your going to hurt it any going with a bottom end cam, if anything it will probably help it some.

Thats what i did ask in the first place!!I know how they work but i still dont have my answer yet no one has answered it yet.

Atv man you keep telling us you know how they work but still continue to look for an answer.:confused:

Rather than get into a tif I will try to tell you what you say you know allready :D There really isnt such a thing as a "bottom end cam" but certain cam grinds will definately increase the bottom end power and likewise for the so called top end cam. Yes a cam designed to enhance your power in the higher rpm ranges can also lose some bottom end torque. This is caused by the longer duration of the typical "top end cam". what you refer to as a bottom end cam will more than likely increase the hp in the higher rpms as well due to the fact that most will have a longer duration than the stock 400ex cam.

I hope that helps

[Sporttrax400ex]

If you get a bottom end cam it will only increase your bottom end your top end will stay exactly the same as the stock cam but the bottom end will increse find a dyno chart it will show ya!!!!!!!!!!!!:devil

[Sporttrax400ex]

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[deansfastway]

Ill bet installing any aftermarket cam in a stock EX will help take the top end out of spode mode.