View Full Version : Rotaz 125 Vs 123...

05-27-2009, 08:21 PM
so I ordered some jet's for the 34mm del'orto from a kart shop today, and was talking to the guy about the rotax they run, about specs etc.

What I'm looking for is the differences between our rotax and the one more prevalent in the states...the Kart used Rotax 125.

I'll also get him on the phone, and find more about a 250cc rotax! haha

05-28-2009, 03:56 AM
there is a engine called the 257. It can fit into the RS frame but there is some work needed to get it in.

05-28-2009, 05:33 AM
They use a rotax 125 here in Australia also. I understand it is called a DD2 and is a 2 speed box rather the 6 speed we use. Others have told me that the motors are totally different. Different barrel, no oil pump, different CDI and rave are things I have read and no of. Others have claimed different pistons etc
Hope thats a start.

05-31-2009, 03:23 AM
ok, so lets get into detail :)

http://s3b.directupload.net/images/user/090508/temp/jtkxs3nz.jpg (http://s3b.directupload.net/file/u/11738/jtkxs3nz_jpg.htm)

this is what they look like, left-hand side the kart barrel and right-hand side a rotax123 barrel.

the kart barrel is approx 4mm shorter, the piston has only one ring and the same compression hight and other dimensions. the rod seems to be the same 4mm shorter then the barrel.

the kart engine uses a 2 speed gear box if the engine is a dd2 which is pretty much the same as the 123/122 from the ports layout. they mix the oil into the fuel tank and they use the pneumatic rave2. they use the 34mm dello carb but they use other needles and much bigger main jets.

the kart barrel shows the 20hp version, which is called rotax max junior i guess, and they have no boost-ports, pretty much like the restricted rs125 in switzerland.

there are 2 different versions of the rotax257, one from a kart with really short transmission ratio and the other one from enduros which is what we want to get if you like to transfer it into our rs125 :)