De-shrouding YZF valves

Your headed the correct direction for sure! It's impressive the amount of increase ron has gotten....I would have to assume the port is enlarge to some extent in order to hit the flow he gets there.

But his 30-35 cfm plus head is probably the mx version, I wouldn't only guess there....Can't speak for him.

Awesome idea with the insertable seats....great way to test easily!

One of the most interesting elements of Ron's post was the fact that the head that made the most power on the least jet was not the head that flowed the most air. The wet lines he referred to are evidence that the boundary layer at the port divider was being defeated when the dividers were sharper and flowed better.

If I had more time, I'd love to play with some good modeling software with this design and work with multiple cam profiles and timing between the center and outer ports. I think there are some real possibilities there.

One of the most interesting things Ive found so far is, that the section of the port, barely 4mm long, has a massive effect on the overall flow the entire way through..

I havent even started to open the port up to chase the 30cfm numbers, ive concentrated on the seat to this point.. once im happy there, onto porting some more...

Proof that without porting one bit, there is good gains to offer a customer purely with a seat job..

One of the most interesting elements of Ron's post was the fact that the head that made the most power on the least jet was not the head that flowed the most air. The wet lines he referred to are evidence that the boundary layer at the port divider was being defeated when the dividers were sharper and flowed better.

I am a little lost regarding what you mean...but if you mean the knife edge was better, I don't think ron said that, the blunt edge was better. I think that's what you said....

When the air.fuel sticks it seems to be worse for the track, but on the flow bench it may not be measureable (wet flow benches can...those are cool! )

Wether you agree with them or not, the idea behind the dimpled valves is the same behind the blunt divider.

Nope. Not what I said. He pointed out that with blunted dividers, the wet lines disappeared, power went up, and fuel needs went down, all while actually flowing less air.

Nope. Not what I said. He pointed out that with blunted dividers, the wet lines disappeared, power went up, and fuel needs went down, all while actually flowing less air.

I thought that's what you said.....

anyways, any new updates?

no new updates boys, im away from the workshop now for a week, heading to Tasmania for a race with our porsche (Tarmac Rally) as part of my day job. Staying in Melbourne at the minute.. I live in Adelaide

Heres what I made up last nigt for a direct comparison, same port, two different seats, OEM and my own design.. My seat is the one on the right at 213cfm

comparative.jpg

Has anyone tried to increase the intake velocity by reshaping the intake port? Not necessarily by making the port bigger, but by reshaping the port.

Has anyone tried to increase the intake velocity by reshaping the intake port? Not necessarily by making the port bigger, but by reshaping the port.

One thing to remember....is whenever removing material, it's getting bigger! But your point is taken, a lot of times you play and play and play with it till you make it worse...then you can either use epoxy to put it back, or some weld it.

Considering that a mod yz250f head can flow about as much as the stock 450 head with much smaller valves and smaller port....there is certainly shape gains to be made with the 450.

Back home now.. Ive started chipping away at the seat design again.. Heres design number 5. Im pretty happy with that now, not sure ill get it much better, this is compared to the oem seat.

Got my low lift flow back AND made a nice improvement up top

comparative2.jpg

exhaust side looks great!

Intake shows nice gains up top...I think if you did nothing else to the bike it would run pretty darn good with just the seat work. Great work...keep us posted on your final set up! (and maybe a dyno run or two!) hahaha....

Take care

I havent actually touched the exhaust since before this thread started.. All my work has been on the inlet since I screwed the seats up. Im gonna be playing with exhaust seats this week. And doing a lot more porting

Ive done a touch more porting, im leaving the inlet at this now... Already spent a lot of hours on this head, and just need to get this bike back together. Ive removed the exhaust seats to play with them tomorrow night, hopefully I can transfer my profile to the exhaust and see the same results...

Heres another graph, the inlet plot is when the head was standard, and then the finished results.

comparative3.jpg

Is it just me, or aren't the graph lines for the intake reversed as to color?

No, its just you... They actually arent in order on the legend. Have a close look, the 2nd one in the graph says intake cfm std and its light purple

No, its just you...

Have a close look, the 2nd one in the graph says intake cfm std and its light purple

Well, then, I'm really screwed up, because when I look at it the second one is light purple, but it says Intake Std. The third one says Intake ported.

correct, im not seeing where you are going wrong??

legend

ex std

in std (light purple)

in ported (some dark colour, maybe black)

ex ported

note, legend order, does not reflect graph order...

Id like to know if you still have issues with it??

OK, I see what's going on.

The line weight on the graph is so small that the colors and legend are very indistinct. You might consider pumping it up a notch.

Sorry for the confusion.

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