ESE's works engine tuner

[Frits Overmars]

No a bad sort of yootoobe in TPI.

Bonus footage of Neil and Rob using the ESE dyno.

Not my pictures, but I felt I should borrow them.

[Jonny snatchsniffer]

We won 4 SKUSA titles with no plug washer, and as a by product I could index the plug much easier.

That's interesting to know, did you use any kind of sealant on the thread or the face of the plug?
Did you notice any difference in power with doing so?

[wobbly]

On the dyno with no washer and the plug indexed it was a repeatable 0.3 Hp, in 40Hp - no sealant , just cranked it up R7376-10.
Probably as much due to the com increase as much as anything.
I data log checked and this translated into a lap reduction of around 2/10sec. But this was also checked for fun against a BR10EGV , and that was easily 0.5 sec slower.

[Storbeck]

A question for Frits, or anyone else familiar with this.

Apologies for asking a question that has almost certainly been addressed before but I have searched and searched and not found a definitive answer.

The shape described by the FOS port shape concept, this is NOT the shape of a template as it would be wrapped around the cylinder wall, this is a flat cross section that would need to be "projected" onto the curved wall. Correct?

And then would it be projected straight onto the wall, or would it be projected at a downward angle as the port is angled downward?

[Frits Overmars]

The shape described by the FOS port shape concept, this is NOT the shape of a template as it would be wrapped around the cylinder wall, this is a flat cross section that would need to be "projected" onto the curved wall. Correct?
And then would it be projected straight onto the wall, or would it be projected at a downward angle as the port is angled downward?

Correct, Storbeck. The FOS port shape concept shows a flat cross section that is projected onto the cylinder bore, perpendicular to the bore axis.

[husaberg]

A question for Frits, or anyone else familiar with this.

Apologies for asking a question that has almost certainly been addressed before but I have searched and searched and not found a definitive answer.

The shape described by the FOS port shape concept, this is NOT the shape of a template as it would be wrapped around the cylinder wall, this is a flat cross section that would need to be "projected" onto the curved wall. Correct?

And then would it be projected straight onto the wall, or would it be projected at a downward angle as the port is angled downward?

Correct, Storbeck. The FOS port shape concept shows a flat cross section that is projected onto the cylinder bore, perpendicular to the bore axis.

I am not sure if I understood the last bit but I remember this bit

The exhaust port isn't canted downward 30°. The flange mounting face is canted downward 30° but the roof of the exhaust duct exits the cylinder at 25°.
The reason is that this angle gives the best flow.

The power valve starts opening at 10,000 rpm and it is fully open at 12,000 rpm. It can keep up with acceleration in any gear. And when you blip the throttle in neutral, the power valve servomotor moves almost as quickly as the revcounter needle.

[wobbly]

The projected shape onto the bore generates the chordal area - this is basically useless for any enlightening analysis , it just guides you toward what are the best physical dimensions at the bore face.
But the Effective Area , that then includes the Cosine of the down angle of the port Chordal Area then generates the STA, when rpm is factored in as well.
This combination of Chordal Area /Cosine / RPM can then be used to create an accurate indicator that will enable the user to hone in on the best really meaningful compromises that are required for their specific project end use.

[Frits Overmars]

The FOS port shape concept has one primary purpose: to keep the piston ring alive.
In addition, it can be used to optimize the blowdown angle.area for any given exhaust port height.

[wobbly]

To be clear Frits I was in no way making any criticism , just stating that your neat guide gives anyone the optimum geometry for the port shape only.
And yes it does generate the maximum chordal blowdown angle area for any predetermined timing, but even that cannot be " used " as this then has to modified to include the duct down angle
thus giving what is actually the point of the whole exercise - the Port Effective Angle Area.

[F5 Dave]

Well it's been a while, and Friday has passed, but this is kinda my Jam. Friday night music.

Throwback. Man I love redhead lasses.

Time for some religious music. Kinda.

[koba]

Hey Team,

I used to post here a bit but sadly my attention has been diverted elsewhere for many years.
On and off I do try to catch up and thoroughly enjoy all the wisdom shared and great banter etc.

So, thanks to all of you who do contribute and make it such a cool place!

One thing I've managed to do as one of my many, many side projects is to put together a TF125 engine as a basic bucket build.
It was really fun and I challenged myself to keep it as simple as possible, minimal fancy tools etc.

It's turned out pretty well so far, the feedback from the riders is very positive.
The bike isn't finished yet, needing a shorter pipe to put it all together but even so it's done well and goes bloody good.

Enjoy
I'm sure I'll get some feedback on things I've got totally wrong in there
Do let me know if there is anything obviously dumb etc. as I'll fix it up so it doesn't put anyone astray.

https://www.bucketracing.org.nz/tf125build

[wobbly]

If you are going to actually build a pipe at some stage I dont get why you are even considering using a design that is so obviously flawed.
The only reason it would be " insensitive " is because the engine is making bugger all power.
Post the .pack file on the site and I will help with something a bit cleverer.

[koba]

If you are going to actually build a pipe at some stage I dont get why you are even considering using a design that is so obviously flawed.
The only reason it would be " insensitive " is because the engine is making bugger all power.
Post the .pack file on the site and I will help with something a bit cleverer.

That would be awesome!

I had one already built on another bike so was just trying to get a quick result, still never managed to test it before moving though.

I'll try get hold of the .pack file, I accidentally left it on the wrong drive on the other side of the world.

[jonny quest]

The magnetic ignition trigger, which in my case is round. Is the middle of this trigger supposed to line up with the trailing edge of flywheel pad at .020" before TDC?
Retrofitting a YZ250 ignition system on something else and just need a starting point.

[wobbly]

Alignment of the lobe trailing edge and the center of the pole is used by aftermarket CDI. The stock ignitions have a timing line on the rotor
that aligns with a small raised marker line on the case - each one has a differing set angle at this point.
You would need to strobe it to find out what rpm they align , and check with a protractor or dial to see what static that represents on the 250.
Some factory manuals show the curve and state the static angle the lines align at.