the difference between honing, boring,porting etc

[kawirider4life]

hey guys...my 03 kx 125 has light scratches in the cylinder wall...i want to get this smoothed out but when i send my cylinder out i dont know what to ask for...the sites show porting,honing,boring,resleeving and replating...what do i need to get done to get this cylinder smooth...and would a scratch cylinder have anything to do with a loud noisy knocking piston? thank you btw if i decide to just get it bored to a 134cc and i send it to eric gorr how long will it take for me to get it back? thank you

[KJ790]

Honing is when a tool called a hone is run through the cylinder. It cleans any glaze off of the inside of the cylinder and puts light scratches in the cylinder that form a criss-cross pattern. This helps the rings seal better. Boring is making the cylinder larger to fit a larger piston in to make the engine a larger displacement. Porting is reshaping the intake and exhaust ports to provide better flow into and out of the engine to increase performance.

[Veccster]

Why do engines need to be ported? I mean, if it makes the engine better and more powerful, why do they not manufacture it that way?

You would think companies would want to make the best product they can; That is s

[L-vie]

Why do engines need to be ported? I mean, if it makes the engine better and more powerful, why do they not manufacture it that way?

You would think companies would want to make the best product they can; That is s

Most production intake manifolds and exhaulst manifolds are a cast piece. The surface is pretty rough. Also the openings may not match the block perfectly.

Port and polish will match the opening (most likely enlarge it) and smooth out the runners so air and/or fuel will flow better. This is normally hand work and labor intensive which equals MONEY.

If you are trying to squeeze out every little bit of power you can, It is worth the effort and money.

For everyday average motor, it's not necessary.

I would think porting will have more effect than polishing. Maybe not?

But, to answer your question, it's all about money.

[eplanajr]

There are always room for improvement from the stock castings, and stock is exactly that, a cast.

[kawirider4life]

thanks guys! seems clearer to me now!

Honing is when a tool called a hone is run through the cylinder. It cleans any glaze off of the inside of the cylinder and puts light scratches in the cylinder that form a criss-cross pattern. This helps the rings seal better. Boring is making the cylinder larger to fit a larger piston in to make the engine a larger displacement. Porting is reshaping the intake and exhaust ports to provide better flow into and out of the engine to increase performance.

thats how my cylinder was it had light scratces that cross eachother...maybe the guy before me honed it??? but he told me it was stock...do they come like this from the factory? thanks and what do u guys think would give me the best power boring it out or porting it...thanks

[KJ790]

Cylinders come honed from the factory, but you should rehone it whenever you have it off just to clean any glaze that may have formed from normal use. If your cylinder has vertical scratches then you have a problem and need it repaired or replaced. If your scratches are the criss-cross hone marks then there is nothing damaged in your cylinder.

Porting can be done to achieve specific power characteristics. Engines from the factory are sandcast. This is a fast and cheap way of making them. It isn't bad, as the port design companies use from the factory is for a broad smooth powerband. The problem is that it tends to have casting flaws. When you have your engine ported the ports are normally made wider, reshaped, and all flaws are removed.

Do not polish your ports. The term "port and polish" is commonly used, but no actual polishing is being done. The term "polish" is used to refer to removing imperfections and making it perfect. A rough port works the best. Many people believe this is due to the rough walls causing turbulence in the air and causing better mixing of fuel and air. This is incorrect however, as the turbulence only increases very close to the wall, thus not affecting the majority of the flow. The true reason a rough surface flows better is due to the induction of a turbulent boundary layer at the surface helps the air flow more efficiently.

[Nosebag]

The true reason a rough surface flows better is due to the induction of a turbulent boundary layer at the surface helps the air flow more efficiently.

Like a golf ball.