ESE's works engine tuner

[F5 Dave]

um. . . .are they applying it to a chipped brake pad? Makes you wonder.

[monkeyfumi]

um. . . .are they applying it to a chipped brake pad? Makes you wonder.

Yeah, that did look questionable (hey! now you can just build up your pads when they wear out!).
It was the temperature rating that caught my eye

[TZ350]

http://www.cotronics.com/vo/cotr/rm_putties.htm

Stumbled across the above, 7032 (rated to 2000 deg F) putty might be suitable for experimenting with exhaust dams or as an alternative to welding the duct for exhaust flange nozzles.

Looks just like just the thing we need for sealing the exhaust dam and for filling areas where we break through between the fins when porting the transfers and side exhaust ports.

[TZ350]

There is a relationship between how wide you make a port, and how gradually it should widen in order to keep the ring healthy.



With a good ring, 70% chordal of the bore is the optimum width. If you make it any wider, the widening has to be so gradual that you loose surface area at the top, where it counts most, because that's the area that opens first and stays open the longest.
The drawing below shows that with too wide a port you have to sacrifice the yellow areas at the top. But sacrificing those areas costs blowdown angle.area. That red port may have more open area, but not where it counts, at the top; the blue port is better.

Unless you keep the revs really low, a single exhaust port with a 70% chordal width does not give sufficient blowdown time.area, but because of the reason I explained above, making the port wider will be even worse. You will either have to use a bridge, add auxiliary exhaust ports, or raise the timing of the single port to well above the 190° that is optimal for pipe resonance.

We have been experimenting with a way of getting more corner area (Green Line) from a wide port.



The trick we are trying is to have a really wide port with a large top radius for the ring and a flat edged stuffer that is 0.5mm or less from the piston for a timing edge. High temp epoxy will be just the thing for sealing the top stuffer.

We have run this on the dyno several times, The idea seems to work OK, but its early days and whether it can be developed into something world beating is yet to be seen.

[TZ350]

There are a few F5 projects on the go, this is Buckets4me and his RG50. And as far as the Team goes, his pretty much sets the bench mark.

[TZ350]

Attachment 237930Attachment 237929

After a bit of a thrash on the dyno....... Red is the old curve, Blue new.
Well worth the hours worked on it. Next step a better ignition. Thanks guys

Giggles RG50 .... (NOS Blue line) .... ... still you do have to have a bit of fun ...

[TZ350]

A single port will not be as wide as the total width of a bridged port, so the effect will be less pronounced, but the principle remains the same: each particle of exhaust gas wants to leave the building ASAP and the shortest path is radially outward.



Therefore the radial lines from the center of the cylinder bore to the edges of the exhaust port describe the initial shape of the exhaust duct's side flanks.

But the duct volume should be no larger than absolutely necessary, so continuing those radial lines would be counter-productive. As the exhaust duct floor drops, these side flanks can be curved towards each other, keeping the flow cross-area of the duct constant. The picture shows the underside of the duct.

One of the Team brought one of these Stage6 road bike cylinders. (the others are listed as Road/Race)



A good looking cylinder but it needs a little work in the exhaust port.



Top edge was marked out and chamfered back.



Then the port roof was raised and the sides shaped like Frits suggested.

In this view, the curved top of the ports is an optical allusion, they are in fact flat and the sides at the bottom that look flat are actually curved up.



I was worried about the Nicosil pealing off above the exhaust port but this cylinder has done a bit of time on the dyno now, and so far so good.

[F5 Dave]

There are a few F5 projects on the go, this is Buckets4me and his RG50. And as far as the Team goes, his pretty much sets the bench mark.

Well that just got competitive in a hurry. Took me years to get that far (and been the same spec since 2004). Good to see my old Swingarm in use.

[mr bucketracer]

There are a few F5 projects on the go, this is Buckets4me and his RG50. And as far as the Team goes, his pretty much sets the bench mark.

holly cow you just matched the gt50

[TZ350]

Good to see my old Swingarm in use.

Your wheels too I think, TZR250 rims on RG50 centers.

[F5 Dave]

Well they came from a similar source/ 2 Wheels in Palmy did that batch, mine originally done by Sales jnr, but I did get one off Wheels which had to be redone. Simons bike which I think is Carls had my swingarm & that Tailpiece (and one of Speedpro's old reed barrels) but there was some horsetrading done by subsequent owners.

[FastFred]

Well that just got competitive in a hurry. Took me years to get that far.

That bike has been around for a fair while, 125's being their thing, I just don't think TZ or Buckets4me have talked about the 50 that much.

Attachment 238016 here is TZ after he gave my poor little 50 a bit to much in the wet.

Attachment 238017 but still rode to finish

Attachment 238018 I wonder why the caned his life insurance (wet and no front brake)

It was a good day at Mt Welly last Sunday, cool, no rain and great racing.

Attachment 245496

Great to have my Grandson out there in F5.

[cotswold]

There are a few F5 projects on the go, this is Buckets4me and his RG50. And as far as the Team goes, his pretty much sets the bench mark.

mine would be the other end of the benchmark

[Dodgy]

Oh, that is where my swingarm (ex F5) ended up. So, you got that from Darren? Where did the pipe. barrel and head end up?

[SwePatrick]

A while ago someone posted(think it was Husaberg) a link to a Swedish site with a simple program wich calculates a sample of 'FOS' pipe for free.
I´ve been in contact with the developer and he asked me what i would like to upgrade the program with.

I said, angels would be nice and if it wasn´t to much work a drawing of the different pieces to copy so one easy could cut out the different parts from the ironsheet.

Well,, he did it and then some..

link again:
http://underdogsracing.com/fospipe/

rgds
Patrick