Rotax Nockenwelle

[Donny]

The following information is from Ron Wood Racing:

Rotax Camshafts (Nockenwelle)

660 cam, 7.9mm lift/225 degree duration. The stock"lawn and garden" cam.
670 cam, 8.9mm lift/261 degree duration.
675 cam 9.65mm lift/297 degree duration (Intake), 9.56mm lift/285 degree duration (Exhaust)
805 cam 9.60mm lift/248 degree duration.
860 cam 10.55mm lift/292 degree duration.

Wood Racing recommends either the 675 or 860 camshaft for good performance street motorads. Has anyone on the forum tried this? Helps performance? Current setup A2 with Bing vergaser.

Danke, Donny

[Martin H.]

Ich übersetz das mal...
Donny sucht nach Leuten, die bereits Erfahrungen mit anderen Nockenwellen - insbesondere mit der von Ron Wood - gemacht haben. Mir war so, als ob wir das mal vor längerer Zeit schon hatten...

[hiha]

Der gute Donny sollte sich mal bei den luftgekühlten Alt-KTM-Fahrern umhören, die bauen solcherlei Getune scheinbar etwas öfter ein wie die MZ-Fahrer. Das war der Eindruck, der sich mir beim letzten Nockenwellen-Fred aufdrängte.

Gruß
Hans

[simmetuner]

Hello,

i drive my Silverstar with a 805 cam, a 36mm Dellorto and the A2 Exhaust! see here -> viewtopic.php?f=97&t=21781

I like it

[Donny]

Very nice simmetuner. One thing I see is that most of the German 504E Rotax come with the Dellorto. In the US all MZ Rotax motorad I see has the Bing. Was the vergaser a choice in the EU and the export MZs were all fitted with the Bing vergaser?

[g-spann]

In the first years of building ROTAX-MZ, they used to assemble only Dell'Orto carburators, until they realized, that BING carburatores could cause less problems in starting and no-load running, also they got a smooth running characteristic, felt like an absolutely different engine...causing a little loss of performance...the last years of manufacture they assembled exclusively BING carburatores...
Come on Dell'Orto-friends, crucify me!!!
I for myself replaced my Dell'Orto by a BING and I've never regret...and I would do it again!!!

[simmetuner]

Yes...

with the Dellorto you can get more Performance but its more work to get it running well.

I choosed a bigger one with 36mm diameter then the original ones with 34mm or 33mm diameter with the Bing carburettor.


Bye

simmetuner

[Richy]

I for myself replaced my Dell'Orto by a BING and I've never regret...and I would do it again!!!

Aaaand, he is really fast!

[g-spann]

Dankeschön, Richy!!

[Donny]

In the first years of building ROTAX-MZ, they used to assemble only Dell'Orto carburators, until they realized, that BING carburatores could cause less problems in starting and no-load running, also they got a smooth running characteristic, felt like an absolutely different engine...causing a little loss of performance...the last years of manufacture they assembled exclusively BING carburatores...

Danke g-spann, I like the Bing Type 64/33/304 CV vergaser on my motorad too. It took a time to tune correctly as my Silvy had been sitting for a long time - BAD fuel. When I rebuilt it, there was a missing part, the diaphragm spring #22 on the picture below. I called Bing USA they said the spring should be there for the MZ Rotax Bing carburetor. When I replaced it the Rotax ran much better, especially at RPM below 3000. So my question is, did spring #22 come with the Bing CV carb from the factory? It runs much better with it installed.

[Richy]

My BING at the Rotax also hasn't this spring.
once I put the spring out of my BMW R80 (identical carburators) into it and there was not much of a difference.
So I still drive without the spring.

No Rotax-MZ is like the other...

[muzredstar]

My Redstar has the spring fitted the bing goes alot faster than the dellorto on the 500r

[Donny]

Thanks - I'll keep the spring as BING recommends.

[Donny]

I have a new Rotax 865 cam I have been planning on installing in my Silvy, but according to the cam specification list, it's is one of the "interference" cams because of it's lift. So I'm having second thoughts, and would prefer a milder camshaft, more like a 800 or 805 cam. Anyone interested in a trade? Danke; Don