Crank profile for DR cilinder

[tyratliffTopic starterBerichten: 18]

I just purchased a 43mm (70 cc?)DR cylinder kit. I know that it is recommended that the profile of the crank be ground down for the best cylinder kit performance. I also know that the recommended profiles for Malossi and Polini kits are slightly different. I was wondering if anyone recommends a specific crank profile for the DR cylinder?

Great site by the way. I wish I spoke dutch!

Tyson

[hansiebModeratorBerichten: 10922]

Thanks mate and welcome 🙂

You can make the ports yourself in your crankcase. This will feed the cilinder more and it goes faster. But its not necessary that you make the ports match the cilinder, at the moment iam also driving a 43mm DR evo and it runs fine with the standard feeding.

Arvidw did the same job with the 43mm DR evo , you need some tools for your multitool and you can do it yourself.

Arvid his page: http://www.vespa-ciao.nl/forums.php?m=posts&q=2936&d=50

You do it by feeling and with a pen you mark the spots were your going to cut some metal of. Just do it with some patience and it will go smooth.

Were your from if i may ask 🙂
Hope that i informed you enough by my post

[EdjuhBijdragerBerichten: 6956]

Ask Arvid

He’s the crank timing expert.

[tyratliffTopic starterBerichten: 18]

Thanks for the replies. I am referring to grinding down the crank for letting more air in. I don’t think I would be comfortable grinding on the cylinder itself.

Tyson

[tyratliffTopic starterBerichten: 18]

Thanks hansieb for the link. I checked it out and Arvid cut his crank 3mm and 8.5mm. That is close to the Malossi spec of 5mm and 10mm. Depending on how much I enlarge the air inlet to the case, I’ll shoot for somewhere close to those specs. Thanks a lot!

I’m still open to other recommendations too if anyone has them.

[ArvidWDonateurBerichten: 6258]

please pay attention to with type of cranshaft you’ve got, there are different ones, for the 45km/hour version and for the 25km/hour version !

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[tyratliffTopic starterBerichten: 18]

Thanks for the heads up Arvid. The motor that I am planning to put the DR kit on came with a Vespa SI head so I’m guessing that (A) it is from a Vespa SI or Bravo and (B) it is the 45km/hr version. I do have a Ciao that is the 25km/hr version so that information is good to know. What are the differences between the cranks and motors for 25km/hr and 45km/hr if you don’t mind me asking?

[KennyVespaBijdragerBerichten: 1477]

the 25 km version has a copper tube in de inlet pipe, its verry hard to drill an it has an 7mm inlet std

grtz Kenny

[ArvidWDonateurBerichten: 6258]

[url]http://www.vespa-ciao.nl/forums.php?m=posts&q=7347[/url]

This is the Howto I Wrote about calculating your crankschaft tuning.

You can see 2 pictures of cranshafts, the first one is the “Snorkrukas” that means that is is build for the 25km/hour Ciao, the second one is the “Bromkrukas” and that one is buildt for the 45km/hour Ciao.

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[tyratliffTopic starterBerichten: 18]

So the 25km/hr crank opens and closes the air inlet earlier tan the 45km/hr crank but the amount of time that the inlet is open is the same? I’ll run your article trough a translator and study it. Thanks!

[ArvidWDonateurBerichten: 6258]

yes, that is correct.

AW50-4t | 13.13 | Gianelli Citypower | 3.2Nm@6000rpm | 3.0pk@6700rpm
Home made engine dyno

[Gebruiker]

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