On the test bench, -PART 2- Malossi 270ccm, V4 cylinder head @ 63mm stroke


After our youngest had thundered “performance” on the test bench yesterday, we will carry out a few more tests today.

Therefore, today we take care of the carburetor adjustment and the optimization of the drive.

Contrary to the diagram you saw yesterday, the CVK carburetor implanted a 104 main nozzle instead of a 106.

In the area of ​​the drive we have that Weights on 15,5g in der Malossi Multivar increased and the originals Piaggio 125 clutch with red Malossi clutch springs equipped.

Since 4-stroke engines usually have a much wider band than 2-stroke engines, the idea behind it is that the power, which is already available at lower speeds together with more torque, can be used over a larger speed range and thus achieve a little more top speed .


The red curve shows the first litter.

With a speed increase of 9500 rpm at 10-20Km / h, the driving behavior seemed very rough.
The working speed of the variator is somewhat high at around 9000 rpm, as there is still very little torque at this speed. Due to the somewhat too rich carburetor setting, it stopped at approx. 110Km / h.

Green curve:

After a few attempts, heavier weights of 15,5 grams will come here. and harder clutch springs (Malossi red) are used. The speed start is significantly lower at 7500 rpm and the engine provides significantly more torque at this speed. Easy to read from the steeper increase in output up to 30Km / h. Due to the lean carburetor setting, the engine now turns out more freely and, coupled with the lower speed level, it can be turned out quickly at higher speeds of over 130Km / h.

Blue curve:

Practically everything like the green curve, but for the acoustics lover without a DB killer ... :-)
The volume limiter swallows a few percent of the valuable work done, but fortunately little.

Well done!


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