Project Silver Fern, milling part 2, determine the control angle and squish dimension

With bearing dummies, we insert the crankshaft into the engine housing to measure the control angle.

We will soon have the storage dummies available for you in the shop.

The two housing halves are fixed with the 4 nuts in the stator housing and the cylinder is for measuring the control angle assembled.

The Newline likes rather low steering angles. At the outlet below 190 ° with a discharge of 28 °.

With a 1,5mm thick Spacer for the cylinder base and a Malossi base gasket, we come up with it
129 ° overcurrent and 185 ° exhaust.

If the squeeze size is still within limits, then we have a very good basis on which we don't really have to change anything.

In order to take the squeeze dimension, i.e. the distance between the piston and cylinder head at TDC, we attach a piece of solder to the piston crown with adhesive tape. The crush dimension should always be determined parallel to the piston pin, otherwise the piston will tilt due to the running clearance in the cylinder and thus falsify the dimension.

For the cylinder head, our choice is that of S&S machined Piaggio cylinder head with an adapted combustion chamber for our purposes.

The Malossi is in one too Version with cylinder head available. However, the cylinder head supplied is intended for a 57mm stroke and is therefore unsuitable for our purposes, as the compression ratio increases with the increase in displacement. This and the rather high proportion of squishy areas in the Malossi cylinder head lead to a higher thermal load.

Mmmh… 1,1mm are a bit tight.

In order to get a higher squeeze dimension, we add an additional cylinder base gasket and thus come to 1,3mm at control angles of 130 ° to 186 °.

Next, the overcurrent channels are adapted to the motor housing together with the 1,5mm spacer.
First it is scrubbed again

and then smoothed.

With the Malossi and Polini 210 it is not only necessary to adapt the motor housing, but also the cylinder in the area of ​​the overflow ducts.

Since the Malossi piston allows the mixture to reach the overflow channels very easily thanks to its open design (Malossi CVF), it is not necessary to mill huge pockets in the lower area of ​​the overflow channels.

The cylinder will be completely milled and tomorrow it will be the innards, i.e. the gearbox, primary drive and the clutch.

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