Dynos often show rather variable data (5-20%) : if you look at the test conditions, you may note that the second test has taken a slight advantage by the ambiental conditions : lower temp, lower humidity and higher barometric pressure. Factors that are quite important on a 2 stroke bike performance.
For both tests, gasoline was the common 98 octane. Correction factor is EEC, that is well known to be not so friendly with "hp" as the SAE or STD, that are older than this. :shock:
TDRs Belgarda were omologated between 27Hp and 28Hp at crankshaft, and if you consider an average loss (for a 125cc - 2 strokes bike) of 1.2/1.5 hp from crankshaft to wheel, you are aligned with the dyno "stock" engine reading.
Dyno-runs from the 90s showed, for my model, powers from 25,5Hp to 27Hp at wheel.
I'm not interested in showing "big numbers", but to share with you the fun that I have in designing, realizing my "special parts", and finally testing them exclusively on circuit. My favourite part of the graph is when the two curves cross themselves at the "stock" curve power peak : this means that I've gained without any "side effect" about 950RPM of pure power after 9500RPM.
The tuning I performed on my bike is "personal", in the sense I have studied, designed and optimized every detail. To be clear, the admission manifold is at its 4th generation along 8 months of study and tests. I have two programmable CDIs (I developed many ignition/PV maps), dedicated carburetion and so many other details, difficult to reassume, without writing a "book".
Anyway, the main are:
1)Cylinder/head/piston : Squish value reduced to 0,65. Optimized/redefined ports and transfers. Copper head gasket. Two rings very light piston (implies rebalancing shaft /countershaft) . Smoothed YPVS design.
2) Optimized inlet manifold, without "boost bottle". Refined reed valve.
3) Optimized original 28mm PHBH Carburetor, dedicated carburetion.
4) Handcrafted air filter, airbox inlet redesigned.
5) Original expansion, but longer silencer.
6) Reinforced clutch and related springs.
A passionate advice : cure precisely the assembly tolerances of parts and and the set up.