Crank timings, original and modified?

[Dea_944tTopic starterBerichten: 87]

Hi,

Could someone check the timing angles on moped/brom and mofa/snor cranks?

I have four cranks of which one seems to be neither moped or mofa (the one to the left), that crank is from a 1973 Ciao.
The opening is like a mofa crank but the closing like a moped crank…. 😕

Timing

Moped (I think…)

1973 Ciao

I will put one crank in a Polini Speedengine and one in an original carter that has a larger inlet port.

From what I understand a moped crank shall not be modified if out in a speedengine but in an original carter with a larger inlet port the opening on the crank can be slightly longer.
There’s a great thread on this here http://www.vespa-ciao.nl/forums.php?m=posts&q=7347&d=0 but unfortunately my Dutch sucks
and google translate works so-so on technical articles.

So the question is should I try to modify the moped crank that will be used in the original carter to match the numbers of a moped crank in a speedengine?

/Dea

[Piet30DonateurBerichten: 1082]

Inlet timing is not an universal number. It is different from cylinder to cylinder and final size of your inlet window.

There is a inlet timing calculator with what you can calculate the right inlet timing for your relevant cylinder.

[Dea_944tTopic starterBerichten: 87]

Agreed but since it’s the combination of crank timing and inlet opening that gives the complete timing it would be very interesting to get measurements on other original and tuning cranks.

Where can I find the timing calculator?

[Gebruiker]

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