[Onebad450r]

Finally got around to examining the head a little closer. There was 1 intake valve leaking and 1 exhaust leaking. I did not have to vacuum test the head to notice this. When looking at the exhaust seat, it was evident that it was not sealing. Usually when you have a good seal the 45 deg. angle on the seat is shiny. This one was shiny only about 3/4" around. One the intake side, same description with carbon build up on the tulip of the valve.

This could be a result of mass production or sometimes on a new head/new valve seats, it's not uncommon to have things settle in with heat. I am not trying to bash Ktm, I have seen this on other engines as well. I am sure with a couple more tanks of gas threw it it would of settled in along with rapid valve wear.

A pic. of the intake valve, most obvious way to tell if the intake valves were tight or leaking

 

[Onebad450r]

Just some more pic's of the head,

Intake side....140cc including the area of the boot,flush to carb....Average length 4", average csa of 2.136 square inches

Exhaust side, single port, 29.5 cc just the port.....2.125" average length.....Average csa of .847" suare inches

I will be making port molds of this head and calculating real csa's at different points instead of the average posted above. Until still tuned........Any info. would still be greatly appreciated

 

[Onebad450r]

After letting this rest for a couple of days. I am surprised at the lack of replies? I guess I am the only one surprised at how big the cross-sectional area (csa) inside of these ports......

There is an existing minimal port area for each combination (bore and stroke) that meets your target rpm. With every cylinder head (or intake) this limiting port erea is the smallest csa in the intake runner. To make a long story short, a formula exists to help you get the correct port area, or atleast evaluate a cylinder head intake size for your application.

To calculate peak power at a target rpm, the minimum port cross-sectional area can be calculated: CA = (.00353677*RPM*S*B2)/690

S = stroke
B = bore
CA = ports cross-sectional area in square inch's
RPM = peak power rpm

I'll use the 450xc spec's, since that is what I am working with for an example, shooting to make max hp at 9000 rpm
(.00353677*9000*2.8346*12.2774)/ 690
1107.76/ 690 = 1.605 sq. inch's......Alot smaller than I calculated?

Remember that the area inside the port is going to determine the velocity. The velocity of the port is just as important as how much the head flows. Everything has got to work in harmony. The exhaust side is a bit more difficult to calculate due to the temp. I will save that and how to calculate the cfm demands for a later time unless someone wants to chime in. Opinions are always welcome, good or bad. I don't mind sharing, just hate to waste my time, if nobody is interested in why things work the way they do.....until next time......let's here some opinions or thoughts

 

[Lost Down Under]

I don't have any input, but am very interested in what you are doing.
I am always interested in new ideas and any sort of technical input.
Keep up the good work, as I am sure there are a lot of other people just reading and taking in your research.

 

[Miles Machine]

I am very interested in this, i just don't understand totally how you got your numbers. Always love new information. Keep it coming.

Thanx

~chad