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I am awaiting delivery of a TSR Evo pipe, which I intend to modify by putting an extra 2” in the centre section. This is a common modification and makes a good pipe very good, but I have never seen it done.

Has anyone got a photo of a modified Evo pipe so I can see the effect on the pipe down-the-line when the 2” is added?

? I shortened mine to get it to rev on a little more

I am told that the extra 2” makes for more torque.

Sticky rode a microlight engine barrelled Lambretta a couple of weeks ago with an extended TSR pipe fitted and he was very impressed. Darrel Taylor has also mentioned this pipe in articles and correspondence.

Worth a try. I can always cut it down again or even shorten it.

The power characteristics of a 2T engine is largely determined by the port timings and other factors like compression ratio etc.
Once that is established, the expansion chamber is then designed to match the specified engine characteristics.
Tuned lengths, match the RPM range that the engine is design to operate in.
So, having a longer pipe for low RPM, on an engine with port timings designed for higher RPM, will just result in a mismatch and less power.
The shape of the disffuser and baffle, likewise, have to match the range of power the engine is designed for.

Saying that......You might get lucky, and blindly improve on a mismatch that presently exists, as it is highly unlikely that standard TSR EVO is expressly designed to work with your present engine characteristics anyway.

good luck.

I got told this
TSR - Taylor Tuning modified ....
power band is from 4700 to 8000 peak power is at 7800 off pipe is well up and it will rev onto 8200.
to modify the pipe remove 10mm to 20mm off both the down pipe and stub it brings the power band by upto 500 overwise ours would kick in at 5200ish hope this helps we find to use a lightweight endcan and no rear bracket,

Fast n Furious wrote:The power characteristics of a 2T engine is largely determined by the port timings and other factors like compression ratio etc.

Thanks. Calculating the tuned length for an exhaust is very easy. Creating an exhaust in metal, bent to shape, is much harder.

Conversely, measuring the tuned length of a known pipe ain’t that easy either. Indeed, when Sticky was preparing edition 3 of the Spanner’s guide to the Lambretta, I did suggest that he calculate the tuned length of each popular pipe and print it in the book. He responded to say that the task was a bit more than he wanted to undertake, and he had found expansion pipe manufacturers unwilling to disclose the tuned lengths of their own pipes.

That, I think you will agree, is a shame. If we knew the information, it would be much easier to select the correct pipe for the job

Norrie Bodge wrote:I got told this
TSR - Taylor Tuning modified ....
power band is from 4700 to 8000 peak power is at 7800 off pipe is well up and it will rev onto 8200.
to modify the pipe remove 10mm to 20mm off both the down pipe and stub it brings the power band by upto 500 overwise ours would kick in at 5200ish hope this helps we find to use a lightweight endcan and no rear bracket,

Hi Norrie. That was the kind of response I was hoping for, though your reply lacks some clarity.

Are you suggesting that shortening the downpipe and stub will bring the start of the power band down from 5200 to 4700?

Can you clarify this?

it brings the power band by upto 500 overwise ours would kick in at 5200ish

Ta

Knowledge wrote:

Norrie Bodge wrote:I got told this
TSR - Taylor Tuning modified ....
power band is from 4700 to 8000 peak power is at 7800 off pipe is well up and it will rev onto 8200.
to modify the pipe remove 10mm to 20mm off both the down pipe and stub it brings the power band by upto 500 overwise ours would kick in at 5200ish hope this helps we find to use a lightweight endcan and no rear bracket,

Hi Norrie. That was the kind of response I was hoping for, though your reply lacks some clarity.

Are you suggesting that shortening the downpipe and stub will bring the start of the power band down from 5200 to 4700?

Can you clarify this?

it brings the power band by upto 500 overwise ours would kick in at 5200ish

Ta

Exactly that m8

With great respect Norrie, I was contacted by Darrel Taylor (out of the blue) today and he informs me that the modifications you recommend are incorrect.

There is some case for shortening the original style exhaust stub when using high duration piston-port engine (original shape ex port), as the stub in not correctly manufactured and too long as supplied. However, if you shorten by more than about 10mm, the u bend will hit the mag flange.

Depending on your exhaust port duration, you can lower the point where the power band starts by lengthening the centre section of the pipe, but DT suggests that you start with the original pipe and see if it needs it. My exhaust port (187degrees, TS1 style) may not need the pipe lengthened.

Let’s see what happens when the damn thing finally arrives.

Knowledge wrote:I am told that the extra 2” makes for more torque. Sticky rode a microlight engine barrelled Lambretta a couple of weeks ago with an extended TSR pipe fitted and he was very impressed.

It's been a while since I read the long build thread, but I thought Gravedigger's Simonini Evo 2 Serveta used a Pipe Design Voyager. Don't quote me on that, you can go down a 100+ page rabbit hole and check for yourself, read up on all the modifications to various pipes that were used throughout the testing period, along with their respective dyno graphs.

Knowledge wrote:With great respect Norrie, I was contacted by Darrel Taylor (pout of the blue) today and he informs me that the modifications you recommend are incorrect.

There is some case for shortening the original style exhaust stub when using high duration piston-port engine (original shape ex port), as the stub in not correctly manufactured and too long as supplied. However, if you shorten by more than about 10mm, the u bend will hit the mag flange.

Depending on your exhaust port duration, you can lower the point where the power band starts by lengthening the centre section of the pipe, but DT suggests that you start with the original pipe and see if it needs it. My exhaust port (187degrees, TS1 style) may not need the pipe lengthened.

Let’s see what happens when the damn thing finally arrives.

Wrongly informed then m8?
Good job I haven’t modified mine pugged away for another day ::::

vegansydney wrote:
It's been a while since I read the long build thread, but I thought Gravedigger's Simonini Evo 2 Serveta used a Pipe Design Voyager. Don't quote me on that, you can go down a 100+ page rabbit hole and check for yourself, read up.

Well, that was an epic read. This is the Killer case engine that Sticky tested with the longer TSR pipe fitted.