Hi Mike:

We were not too succesful. The manifold that my friend got from KS was 30 cm long, in my opinion, not enough. Our first reading was 6.500, but not consistent, dropping quikly to 5.900 as soon as the pipe got hot. We only coud make a cople of attempts, playing with the PTFE gap. Next was 31 cm. Better, but not stable. 32 cm long: 6.500 stable and 95 ΒΊ, good but not enough because that is the same reading that with the pits muffler. No more PTFE was available, so I took the manifold to home to add 4 cm of steel tube, but we haven't tested it yet.

The wether today is not very good in Madrid [] it's ranining ...

If rpm is not stable, the prop you use is too big, or the header is too short.
he prop must allow the engine to work above the torque peak, or the engine will loose rpm when the pipe gets hot.

I used a 24x10 3W wood prop in my test, which was a lot of load for the standard engine. It produced 6.81 hp @ 6600 rpm. With the same pipe setup, the engine produced 7.1 hp @ 7100 rpm using a 24x8 3W prop.

With the pipe set up well, one could expect about 1hp per 1000 rpm from the standard engine.

Yes, I agree. We will try a longer set up, and probably change to Mejzlik 24x10 (lower load than Menz, I think). I'll report results.

3W has 1.31 prop factor, and Mejzlik has 1.18.
Using the 24x10 Mejzlik should bring you at least 7700 rpm if the KS tuned pipe is any good, and tuned for best hp for the 24x10

So you suggest running 24x10 Menz with MTW tuned piped? I saw pipe test on your pages but what was the prop used? 24x8 3W?

prop was 3W wood 24x10, actual measurement 24x10.2 , which ran 6600 rpm with type 1 RE2 pipe and 400 mm header. This header length had best torque at 6600 rpm, best power at 7100 rpm with a 24x8 prop. (static)
Current RE2 pipes have been designed to allow a shorter header at the same resonance rpm
The prosport runs stronger than my standard IRS test engine, which I found slightly low on power as compared to customer data. I think it better to test a lowish end engine, than boast power that is not there in every engine.

Edit:

P.S.
I ran a whole range of props ranging from 21x10 to 24x12 and 23x10x3, with different canisters, tuned pipe and header lengths. Rpm ranged between 5500 and 8200.
If you use my spread sheet, select prop and rpm, you can picture the found hp in the published power graphs.

7700 ???

We did some tests this weekend and we were happy with the results, but it is not as good as 7700. Header is 34 cm long (13.385 in). There is a huge amount of power. Mejzlik 24x10 at 6.850 rpm. Menz S 24x10 at 6.690 rpm. This engine seems to be a beast !!!

Oops, slight obnoxia of the brain. Should have been >6700!
The mtw pipe tached ~6800 with the Mejzlik 24x10 and 400 mm header length. A slightly longer header of 425mm would have been perfect to get rpm a little above best torque rpm.

ours is KS ...

Yes Javier, you mentioned that earlier.
What type is it? 1060/4 or the new 1060/5? KS just puts the last 2 digits on the pipe, so it will say 60 (pipe diameter)

It is a KS tuned-pipe 1060-5 B

BTW, on Monday, I ordered my new 116 ...