Intake Port Dimensions

[Anonymous]

Since I am stuck waiting on a valve cover gasket, I was tinkering last night and took some intake measurements. For those that followed some of the porting threads you will remember that a website was posted ( http://mototuneusa.com/thanx.htm ) that showed performance increases with smaller ports that resulted in higher intake velocities. Some thought that since our bikes are "old-tech" that they would already have small ports and could not benefit from this technique. Well, my 1100 has 27mm valves and using Motoman's formula (make intake port height 65% of valve diameter), I would need an intake port height of 17.55mm. So I got out my inside calipers and checked that out. The intake ports have a height of 25mm as it turns out. So, I would need to add 7.45mm of epoxy to achieve Motoman's numbers. It would appear that the 1100's ports are big enough to possible benefit from some epoxy work, after all. Now I just need to find money, time and a spare head all at the same time...


Mark

[rosco15]

I have a good cantidate laying around. Something thats seen better days, but is still usable. Give you a good price.

[gsbill]

I would recommend porting on a flow bench

[Anonymous]

I have a good cantidate laying around. Something thats seen better days, but is still usable. Give you a good price.

Unfortunately, I have neither time nor money at the moment... :? I may get back to you when things permit. Thanks for the offer.

I would recommend porting on a flow bench

If I had one, I would. I have been toying with the idea of building one using a couple of shop vacuums as the vacuum source. It would suffice for me and allow me to ensure all four ports are matched. Too many projects and not enough time...

Mark

[gsbill]

Having a device to measure air flow is critical to good headwork. Where the air is flowing and how much is something you need to know. Adding epoxy or taking material out, including the shape of your intake runners all combine to create desired results.