Kz 1000 Head porting

the ports on a stock kz head suck ! :laugh: youre never going to make one perfect without tons of time and money,what im saying is a gentle curve is better for moving anything be it air/gas/water or anything else and doesnt require a giant oldstyle pro stock sized port to compensate for the restriction.kind of like running a 2" drain from a washing machine and running it into an 1 1/4" 90 to get around a tight corner right before dumping it into a 4" plumbing stack,it will run great till it hits the 90 then things go to hell .

I think you should try to keep the port small but try to straighten it out a bit. This keeps the velocity of the air more uniform. This is the reason most newer bikes use a downdraft type carb on them... the intake runners are pointed straight at the bottom of the valve as are the carb venturis. the less angles the better it will flow.

The ports should be the narrowest at the bend right at where the guide is. this keeps the vaccumm high enough to pull fuel out of the carbs.

exactly,keeping velocity high is secret to a good cylinderhead.but you also need it to be unrestricted as much as possible by sharp corners.

gearhead119 wrote:

I think you should try to keep the port small but try to straighten it out a bit. This keeps the velocity of the air more uniform. This is the reason most newer bikes use a downdraft type carb on them... the intake runners are pointed straight at the bottom of the valve as are the carb venturis. the less angles the better it will flow.

There are 2 basic types of downdraft port arrangements.

1 - Those designed to tumble
2 - Those designed to dump.

The ports should be the narrowest at the bend right at where the guide is. this keeps the vaccumm high enough to pull fuel out of the carbs.

Actually, on a 2 valve head, the area on either size of the guide is critical to achieving high lift flow. Bowl volume does two things.

1 - Gives the area needed to achieve the flow.
2 - Sets up a high pressure region right behind the valve.

There are times when the bowl will require 100% - 103% of the valve area in order for the port to reach it's full potential.

There are times to use that and there are times to not use that much area.

Generally, what gets done to make the top numbers come up, will have a tendency to make the bottoms numbers go down.

You're starting with 68CFM. Push that to mid 80's and you WILL feel a difference. Looking at what's been done so far, I'd estimate you're in the mid to upper 70's.

Continue on with the careful, well belended work you've done and you'll have a nice cylinderhead to be proud of.

I just fell in love with that PORT JOB!
Anybody got some combustion chamber work that can match up with these ports? If so post in this thread please.

this is one of my heads,it`s not finished yet ...

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I`m sorry,don`t know how to post more than one pic ...

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