Cam timing for what type of riding?

[witech]

For those of you in the know what type of cam timing do your riders like for certain types of racing. I know for GP ice and high speed trails we have found that going at least 2 to 4 degrees higher number than stock gives give great top end for straights. What is you favorite for mx racing ? Im really stumped on the drag engines . Should I stay around stock for more low /mid or raise it for more mid /high. I guess length of the drag strip determines that? What about lobe separation? What about dune hill climbing.Is that about HP or torque?
If you have dyno charts to show your preferances that would help. I will try to get some together as well.

[Iliketogofast]

I don't know anything about timing and degrees and blah blah blah on a four-poke, but I know that for MX you'll want low-mid and for drag you'll want mid-top.

But really, how much can timing advances help a four poke when it comes to changing the actual power curve? I've never heard of that even.

As for hill climbing, you want gobs of HP and torque is nice but it takes a back seat really. Torque is for pulling stumps out of the ground and hauling dirt, silly four stroke rider. :D

I'm probably not much help, but there's my .02. :blah:

[witech]

Here is an example of going for max power at all costs. The one with the most power had some extreme cam timing but the one with the timing closer to stock had a much better torque curve. You would need to ride that higher hp one on the rev limiter to beat the lower hp motor.

[witech]

chart

[GPracer2500]

Here's a WEB 208 timed straight up (red) and then retarded 4 deg (blue).

http://www.trx450r.org/forum/uploads/post-2550-1128539194.jpg
[test courtesy of DASA]

I've seen similar testing with other setups but can't find them quickly. Not long ago someone (WppRacing, I think) did a test with retard, straight up, and advance to show the difference. I can't seem to find it though. Pretty sure most of what I've seen has been with Honda SOHC engines so no lobe separation angle changes on those.

[witech]

Thats a great example. I know years back before I had a idea on what to do I figured advancing the cams was the way to go. I did one engine and it had gobs of low end tractor torque but it was a pooch on top end. You could drive around in high gear all day long at low speeds and it wouldnt even sputter. Its a tough balance to give the racers the big numbers while still keeping the low end which is what is going to get you out of the corners quicker. Stroker cranks sure help out a lot there.