Porting and Reliability

[toalco-kdx]

I am looking into getting my bike ported and I have been getting mixed answers on whether porting makes a bike more or less reliable.

One person told me that the added air will cause the engine to run alot hotter making the piston more prone to seizing. Another person told me that the engine will run alot smoother and cleaner and that there wouldn't be any more of a chance to seize than there was before. So who's right? Will it be less reliable, stay the same or get better?

I have a '00 KDX 220 and I like the fact that it's very reliable and doesn't require as much maintanence as a fullout MX bike. I haven't needed a top end yet and I haven't even fouled a single plug and I'd like to keep it that way. Keeping it reliable is a big factor on whether or not I should get it ported. I do not have the very much mechanic skills and I'm not racing or else I'd just buy a CR250 or something which wouldn't need to be ported to gain power.

If anyone has ANY experience or info please mention it.
Thanks.

 

[Studboy]

Unless the tuner opts to go with an overly large exhaust port (which he won't unless you choose to go extremely radical.) reliability will not be compromised.

 

[Rcannon]

I have wondered the same thing....Is it fair to say "more horsepower will equal more wear"??? I dont know?

 

[jmics19067]

I dont think a properly ported engine will increase wear. More horsepower does not really equal more wear. more of a load on the engine or more rpms will. most times a properly worked engine can last longer than stock by cleaning up the problems inhereted with sloppy production tolerances you can get the engine to run the way it was designed to run more efficiently and /or tailor the power to be more efficient for your type of riding. Matching the type of engine with the type of loads it will see will increase its dependability. If you are racing and you use every last bit of your engine and then you port it and you still use every last bit than your wear will accelerate because you are able to increase the demands on the engine.

 

[toalco-kdx]

thanks for your opinions. how much does the porting increase the HP? how noticable is the power increase? and should i get an aftermarket piston or will the stock piston handle the porting fine? thanks.

 

[Studboy]

How much the porting will increase the HP depends on what bike and what type of porting you select... for example Mid-Top porting will give you the most PEAK H.P. numbers but what you are looking for is more power to suit your riding style and conditions. The stock piston will work fine if that is what you prefer, but I would try a WISECO and be careful with the break-in.

 

[jmics19067]

asking how much horsepower you can get by porting is like asking how much gas it is going to take to fill up my car. High horsepower numbers & high rpms don't really mean much since it can only help a selected few in selected circumstances. Instead of going for bragging rights you should realistically look at where most of your problems are and solve them first.

 

[toalco-kdx]

when i asked about the HP and performance gain i was just trying to find out how much of an increase in power porting makes. if it doesnt make a reasonable increase then there is no point in getting it done. just like an aftermarket silencer, they add a HUGE .5 HP and all they do is make your bike a pound lighter. im not just getting it done so i can brag, because there have been situations where i wished the KDX had more power and porting seems like a good way to get more.

 

[marcusgunby]

Some bikes are well ported and gain little-some are badly ported from new and gain alot-i suspect you can have some reasonable gains on a KDX but it maybe in the top end where you dont need it.

 

[jmics19067]

Horsepower is a function of torque x rpm.

in other words if you have 2 engines producing the same amount of torque the one spinning at a higher rpm will have higher horsepower numbers.

the kdx is very well designed for having smooth easy power across a wide rpm range. Although I am not a proficient engine builder /tuner I can see how getting engine work done could give you a decent amount of gains in one area of your power spread at the cost of the others. Basicly, for lack of better words, what you can do is take all the torque your engine makes across that wide rpm range and bunch it up in a narrow rpm range. If you make your engine stronger at the bottom end of the rpm range for more grunt coing out of turns etc.. it will fall flat at high rpm straightaways. You would have low peak horsepower numbers but you would have higher torque and horsepower numbers at the lower rpms the engine was tuned for.

If you were to have the engine ported so it would be better at high rpms straightaways you would have higher horsepower numbers because you shifted the engines ability of creating torque to a higher rpm range at the risk of making the engine harder to ride in tight turns.

Carburation, reeds,reed cage ,pipe and physical engine dimensions are a limiting factor though