Well since the engine is apart already.......

[andersonee4]

What does a high performance cam do for me? Is it worth the expense. 250sx. I am putting in a high compression piston and figured since im doing it, i should do s'more. Can anyone shed some light on what the purpose of high performance cams accomplish?

[wonderboy]

Well, the two things the cam can affect are how far the valves open and when they open. For maximum horsepower, you want the intake valve open for a long time, and open really far. The compromise is usually that you can make more power, but that the power is at a higher RPM. High lift and long duration favors higher RPM operation. There are a ton of aspects of the cam lobe design that have to be considered: how agressive the ramp up is, when the intake opens relative to the exhaust valve closing, etc.

If you go high lift, you have to be sure your valve springs won't go solid (compressed so far that the coils hit each other).

It is pretty typical that if you are going to make induction changes such as a cam or other intake mods (porting the head for example), you should also upgrade the other aspects of the system such as the exhaust and carb.

[Yamaha_Rules69]

The cam will change the torqure curve, if you wanted a race motor, it would allow the enigne to make the most power at high RPM. On a 250SX the only major downfall is the shaft drive. You cant change the gearing, so you can never go faster than the top speed it goes now, but with a performance built motor, it would have a lot faster acceleration, and get there a lot faster. That is the onlt gain, as you would loose some of the bottom end building the engine for race mode, and it wont be as good for the tight trails.

[Dirtcrasher]

Just remember that your top speed is limited and your looking at 500$ easy for a cam and springs with retainers and hardfaced rocker arms.

Enjoy that trike in it's limitations (I learned my lesson.....) and then search for a decent 350X to roll with and BONE STOCK it has plenty of power and a nice rigid rear suspension/axle........

[andersonee4]

thanks for the tips. I think ill just stick with basic mods. the high compression piston, maybe ill put a 350x carb on it and some exhaust... if i can ever find one.