GB: On
Thursday, August 18, 2022 around 2 pm, the time had finally come!
The moment of truth about the potency of the 600cc engine was upon us!
The black original engine of my HONDA XL600R PD03, which I completely rebuilt from scratch, should be “felt on the tooth”, i.e. the performance of the engine should be tested on a p4 measuring system in order to be able to prove its potential "black on white".
The new engine was reinstalled and revived by me on March 10, 2022 after a good 5 years of construction, the (red) replacement engine was removed, and is now on my kitchen cabinet. Mom is not amused!
Since its reinstallation in March, the new engine has covered exactly
2,436km (1514mls) until its test.
The
p4 measuring system, a chassis dynamometer, is located at MGH in 41462 NEUSS and is not far from Düsseldorf. It is not the first visit of my XL there, as the pictures in my gallery show.
IMG-3545
IMG-3548
IMG-3549
IMG-3550
.
The workshop master of MHG (the guy in the pictures) and I push my moped to the stand and fix it there with two red straps on the fork. He sets the parameters for the test on the PC, I start the machine and he runs through a complete test run. It only takes about 3 minutes, then the haunting is already over!
The noise of my 600 at high acceleration is deafening and hellishly loud!
He tolerates it only with hearing protection. -
Wimpy! 
A
small review of the engine data of an XL600R PD03, which according to the manufacturer HONDA (allegedly) it should have! Unfortunately, even the official data within HONDA are inconsistent and confusing depending on the source (brochures, WHB, vehicle registration, etc.)!
Manufacturer engine data XL600R:
(WHB=Workshop Manual) The fact is, in 1983 the people at HONDA were particularly happy to exaggerate their performance figures! This was also confirmed to me by the workshop master of MHG with his many years of experience, who in his past has tested countless HONDA's on his test bench with poor performance!
The measurement result of the test run of my XL looks like this. First comes the measurement curve of the determined power at the rear wheel on which the power dissipation of the drive train is then added to obtain the power at the crankshaft.
Power (crankshaft) = power (rear wheel) + power dissipation (drivetrain) Determined power on the rear wheel or "diagram rear wheel" 
Power on the crankshaft or "diagram clutch": 
.
The official measurement result of today (18.8.2022) for the black original engine of the XL is: 
The evaluation of the measurement diagrams: Although my tested engine with a
maximum of 43.1 measured hp exactly reaches the specifications according to HONDA WHB 1-2 – albeit at slightly higher speeds – I am disappointed. My high expectations of the expected maximum power were clearly missed by 3 hp to 4 hp! –
“The mouse does not bite off a thread!” 
It is noteworthy, however, that the engine provides its 43hp over a wide speed range of around 700 RPM as if on a plateau! That's ~10% of its (green) speed band. Between 6,000 RPM and 6,700 RPM, the diagram shows that the new engine delivers its maximum power at 43hp!
With the
maximum torque, on the other hand, there was a small positive surprise!
It is surpassed by 5 Nm. That's 9% above the factory specification! -
Not bad, Mr. Specht! 
Even the
top speed of 170km/h can reach my XL not only on the test bench, but also in real operation with me on it, as I am very aerodynamically shaped!
When riding my XL I notice very clearly that from 4,000 RPM the mail goes off like hell and lasts until 6,000 RPM, then remains constant.
However, I miss the famous "icing on the cake"! 
Another advantage of the newly built engine is the
apparently lower fuel consumption. The fact is that I have not had
a fuel consumption of 3.63l/100km for YEARS! The subject must first be examined in more detail by me, which is not trivial, because consumption is subject to many parameters. But there is evidence that indicates that the consumption of my revised engine (compared to my red replacement engine) is
about 20% lower. Another advantage of the newly built engine is the apparently lower fuel consumption. The fact is that I have not had a fuel consumption of 3.63l/100km for YEARS! The subject must first be examined in more detail by me, which is not trivial, because consumption is subject to many parameters. But there is evidence that indicates that the consumption of my revised engine (compared to my red replacement engine) is about 20% lower.
That's only half the story so far. The full one is that on
13.10.2008 – freshly installed with the piston of the first oversize – a
first visit of the original engine took place on the test bench in Neuss. The
official measurement result of 13.10.2008 for the black original engine of the XL shows the lower diagram, which can be found on page one in my picture gallery:
.
His (most important) measurement results from 13.10.2008 are:
.
A comparison of both measurements from 13.10.2008 with that of 18.8.2022 proves that 14 years later:1.) the maximum horsepower is identical to 43hp, and that at the same speed!
2.) the new maximum torque of 53.6Nm (again) is 2.2Nm (=4.3%) higher, and that at identical speed!
The plus of 4.3% should also appear at the maximum performance! Why don't they do it? That would be exactly the 4 hp extra I missed! (2hp + 2hp camshaft.)
I am now licking my wounds and trying to find out why the additional horsepower calculated by me does not appear in the peak power of the new engine! I already have a few ideas!
I'm sure I'll find and uncover more hidden horsepower in my XL600R in the coming years! Some "bottlenecks" are already known!
At the crowning conclusion of my major project, I have
a little treat for everyone! There is a
short video of my machine with this engine from the test run on the p4 measuring system in Neuss of 2.5 minutes duration, which I shot and uploaded to YOUTUBE (with the value support of TCP).
Video Name: Gabriel’s HONDA XL600R von 1983 auf p4-Meßanlage bei MHG 18.8.22 Video Link:https://youtu.be/hisum37AZV4
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, seeing that in 2022 the graph is more wavy and less erractic compared to 2021, makes me to believe you drove more highway or kept steadier speeds 
. 
