TIP 1: Tune carburettor with masking tape of the air inlet filter

The problem with misaligned carburetor is that you do not know if you go too rich or too lean. So we mask part of the filter inlet with tape. If the result is worse then before then take a smaller nozzle. If the result is better, then close more of the inlet with tape until you have found the optimum. Now install next larger nozzle and do again.

TIP 2: Engine idling is not adjustable

One day the idle on the right carburetor was away. All cleaning activities and ultrasonic cleaning were with out avail. Also from the other side, I heard of this phenomenon and it took about a year until I found out the reason. Finally I looked to the blue prints of the carburetor and determined that from the pilot a hair-thin channel leads into the intake area, downstream of the slide. If this channel is blocked, pure ultrasonic cleaning fails. What you need is a strong blast to open the channel.

 

Image 1: Carburetor from the front - idle jet            Image 2: Carburetor from below - idle jet       image 3: Carburetor from behind - side air hole
                                                                                  blast in here                                           blast in here

TIP 3: Clutch slips

A problem is the clutch of the RD, which began to slide from Stage 3 on. After searching the net it became clear, that today's high-performance gear oils do not fit to a wet-running clutches of the 70ies. Shell Advance VSX 4T 10W-40 oil seems to be well adapted. To be on the safe side, I increased the pressure of two of the six springs by using a 2mm washer instead of the 1mm. Thereafter, the clutch was still well adapted for 6th Stage

TIP 4: Where do the rills come from on the piston skirt and cylinder button

I took about two years when I racked my brain, where rills on the piston skirt and cylinder bottom does come from. Even after meticulous cleaning of the entire intake region, the problem was there. I have always polished off the rills with 600 abrasive paper to see how the cylinders look at the next opening. I saw always the same sad picture.
The vital clue came from Marco Boehmer: Oil coal in the exhaust pipe, which is pushed back by the reflective wave in the cylinder.

Now I filled up a pound of M6 and M8 bolts in the exhaust pipe, shacked it vigorously and then emptied. After 4 or 5 runs a small heap coal had come out of the pipe. The problem with the rills was solved from then on.

Tip 5: Effective and simple tuning measure

5.1 Air filter case conversion

Reconstruction of the air filter and larger jetting.
Performance increase was not measured but clearly felt

5.2 Modification of the Exhaust Whistle

This change increases the right low speed  torque

5.3 Squish Gap Reduction

Change in the combustion chamber shape by reducing the squish gap and enlarge the combustion chamber brings nearly 10% over the whole speed.Performance gain of 2 kW to 24 kW.

TIP 6: Portable Dyno "Dynolicious"

From a discussions in different forums I know about the software Dynolicious for iPod and iPhone. This soft measure via the gyro censors the acceleration and counts engine power, acceleration for 1/8 and ¼ mile and so on out of it.  The calibration is done by the exact input of the total weight of the bike (including weight of the driver). Every thing else is done automatically. The pity is that the app does not make a correction of the air drag. In the result peak power measured only in the lower gears, what is not the case in practice. On the dyno my RD reaches max power at rear wheel at 4th gear. But the result was amazing. The calculated power was 24 kW the result from the dyno of Marco Böhmer was 24.9 kW. That’s pretty good.

 I did 3 tries with dynolicious, all three on the same road. The 3rd one in the opposite direction as 1st and 2nd. All three were 24 kW (image 4). 

 

Image 4: 24 kW with 2.75 mm squish gap, compression 1:10                      Image 5: 28 kW with 1.5 mm squish gap, compression 1:10

Over time, some modifications have been made (squish smaller, digital ignition,Image 5). It can be seen that I had a problem with knocking combustion. The performance suddenly breaks down in 4th gear.

                                           squish gap              squish gap 1.5 mm 
                                               
                                            2.75mm                 and variable ignition timing 



                                              24 kW                  28 kW

0-10 km/h:                             0,53 sec               0,53                          

0-20 km/h:                             1,22 sec                1,05

0-30 km/h:                             1,81 sec                1,64

0-40 km/h:                             2,32 sec                1,96

0-50 km/h:                             3,07 sec                2,29

0-60 km/h:                             3,73 sec                2,93

0-70 km/h:                             4,17 sec                3,41

0-80 km/h:                             5,23 sec                4,31

0-90 km/h:                             5,95 sec                5,0

0-100 km/h:                           6,86 sec                5,71

Unfortunately Dynolicious does not display single measurement of the instantaneous acceleration in "G ". This blocks the possibility to correct the influence of drag manually.

For the test described above I used a magnetic map tank bag like shown. The iPhone is fixed inside it in a Styrofoam plate. Under the iPhone a bubble wrap is fixed as vibration damper. 
Former measures by using an iPhone Bike Mount could not be worth due to vibrations of the mount.