KDXRIDER.NET

One of those basic things that should be done if you have the chance.

A few pictured down page 27 from the signature or hear:
http://www.trials.com.au/forum/viewtopi ... 389#p37389

Very cool. Thanks for that. I'll have my engine all apart this winter so that should be a good time to do some case matching.

Most people don't realize how much there is to gain from what you are doing. Way more from porting and matching than any carb will ever give you

Did the cyl drop at all?

I've often wondered about the boost transfer ports under the reed box. The edges in the crank case are just flat bottom, square edged.

Anybody ever open those up to a V edge or something to ease the flow into those ports? Anything to be gained by doing so?

Yes I did that on my cylinder just a couple weeks ago. I doubt that that alone will do anything significant. Just as cutting a Reed cage alone will show any gain. It is when all things ad up is where the gain is

Hay thanks for the walk down memory lane. I had to make that decision over a year ago and came to this conclusion.

Ok this is my thoughts to date 14/1/2016.
To fin or not to fin that is the question.

I asked a expert and he gave me the usual answer.
Q Tioli: do you fin the splinter between the transfer ports?

A: maybe.

Interrupted as a typical answer, work it out myself. So the answer is within my reach.

So how do you do that? I have two areas that need it. The transfer ports and the inlet bridge ports.

Fin or not to fin, when is it a fin and when is it bullet nosed and does it matter.

Ok take a area scan. How much area do I loose if I fin?
Determine flow.
Resolve shape.

Area known and ready to be assessed against improved flow.
Flow direction determined.

Recherché bullet design, fish, ship and plane.

A: for the transfer ports I will do a 20% fin and clean it up. There is so much going on around there I don't need to mess it up.

The inlet bridges are so different. Area is a bigger player hear. I have the VFORCE reeds so the flow Is shared amongst 4 streets. Area map it every mm from when it leaves the reeds to in the cylinder. Compare advantage to disadvantage of effect of shape to flow.

A: I just don't know but I will choose not to fin for the following reasons:

Minimal loss of area.
Maximum strength support for the rear bridges against cylinder base.
I do not want to develop top end at a loss to bottom end. I want to encourage bottom end so dilleberetly did not fin the bridges where they enter the under cylinder area. I did clean them up which did increase area by about 20% but the reverse was kept flat as a anti flow tool. Planed reshape of rear boost port designed for bottom end power The flow through that area will have a big influence on flow through rear boost port. I want to lessen and redirect.
The in come lead edges of the rear bridges are leaning towards just clean them up. The lead edge has to compensate for expansion as the charge leaves the reeds. The advantage of volume in the area to proposed increase flow is just not there. For estetic reasons it's attractive but function overrides

That's the opinion of this left handed dyslexic.
Thank you brother.

If you want see the same with pictures go to the bottom of page 27 from the signature

I was wondering what to do about those ports as well. I decided to leave them flat-bottomed for the following reasons:

Making them flat seemed to be intentional. It isn't like other areas that are sort-of rounded off and additional grinding could result in gains. I wondered if it was an oversight on the KDX, but I found some pictures of other makes and models with similar ports and they were flat as well..

I also looked for pictures of work from reputable porters. Not too many of the KDX, but of the ones I found no one seems to be reshaping the flat part of those ports. That is good enough for me.

Here is an old thread of EG's work on a KDX: http://www.kdxrider.net/forums/viewtopic.php?t=5986

When you look at the size of the small 220 rear port and large 200 you can easily see the intended power characteristics.

Verrrry interesting......... Thanks for the replies.

Scroll down a little bit and there is another cylinder where rear ports where left flat: http://www.thumpertalk.com/topic/100353 ... -98-motor/

I'm a little surprised to see how much of an edge was put on the intake and transfer ports. From what I've read, a rounded edge flows more smoothly, like a plane wing or the bow of a boat.

What are the thoughts on that?

How can you realy know unless you have gone through half a dozen barrels to find the right combo and then there is probebly five ways to get the same result.

Off the top of my head I don't like the exhaust port as it seems small and suited to a grunty motor. The transfer splitters are bias to directing charge to the main transfer ports which is probebly not that nessesery for a lower revving motor. The bridges for the intake port are shorter than ours so, you know?
And I did not know prox make forged Pistons.

Everything is so grey when it comes to "The" right way.

For the KDX I'm just playing it safe and ticking off on all the basics and slanting every touch to a planed carastistic. Very happy with the 200/220 motor.

My brother built me a race motor once. It was the strongest out there yet to look at it you would not know why. The young grasshopper would think big is best yet the master could target a prescribed result by slight of hand.

I'm no master just a coattailer