Author Topic: Rotax egines  (Read 689 times)

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Offline Slakewell

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Rotax egines
« on: February 05, 2020, 04:47:42 PM »
Did Rotax make an open class engine before 75?
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project. Dont need a pickle just need to ride my motorcickle

Offline Watto HVA 1

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Re: Rotax egines
« Reply #1 on: February 06, 2020, 04:50:34 PM »
In a snowmobile maybe.. :o

Offline djr

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Re: Rotax egines
« Reply #2 on: February 06, 2020, 08:50:06 PM »
Could be wrong, but I think they only had the 175 + 250 disc valve engines in 1975


Offline supermoto.mc

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Re: Rotax egines
« Reply #3 on: February 09, 2020, 09:34:43 AM »
No but you could fit the long stroke Conrod maybe and go to 280 your bore should be 74 !

Offline pokey

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Re: Rotax egines
« Reply #4 on: February 09, 2020, 10:37:47 PM »
It reads kind of obscure but FWIW

Canned ham
Quote
In 1974, an attempt is made to enter the 500cc Motocross class. The Type 406 is introduced via the intermediate step of the Type 366 in 1978, with an output of approximately 48 HP at 6,700 rpm.

I read that as they started with a probable prototype(maybe type 366) in 74 but didnt get there till 78 with the type 406

https://www.rotax.com/en/100-years/history-of-motor-sport.html

Offline sleepy

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Re: Rotax egines
« Reply #5 on: February 10, 2020, 12:37:18 PM »
No but you could fit the long stroke Conrod maybe and go to 280 your bore should be 74 !

Length of conrod doesn't change the stroke only pushes the piston further up the bore. Would be possible to weld and re-machine bigend hole further out to increase stroke and make and fit a larger sleeve/piston to get one into open class but gets expensive.

Offline pokey

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Re: Rotax egines
« Reply #6 on: February 10, 2020, 12:41:44 PM »
Ummmm yes longer rod doesnt change cc but it does change the speed of the piston;)


Offline Slakewell

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Re: Rotax egines
« Reply #7 on: February 10, 2020, 05:15:16 PM »
Thanks for the info guys so the short answer is NO
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project. Dont need a pickle just need to ride my motorcickle