Does anyone know how much horsepower the old 521cc motor made? *A dealer told me that the sled made 98 horse. *Does this sound too high to anyone? *Mike

P.S. *Anyone hear if winter is ever going to get here? Sad, but with this crap I'm ready for spring already. *http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/sad.gif

BlackKnight
Your dealer is in the Ball park,i have a 85 plus with
that engine and used to talk to the boys at FAST,
they told me those engines made around 96hp.I gave
mine a .049 sqish, polished exhuast ports and geared
down to 22-38 from 26-38,no overdrive in these babies.
This old sled is fast,it will run about 155km if you give her
a little room,and it used to out drag every thing up until the
94Machs came out. I still have it and keeping it as a collector
as 85 was the first production independant front end for bombi as far as i know.
* * * * * * * * * * * * * *hope that helps
* * * * * * * * * * * * * * * GREYGOAT

THE FIRST FOUR YEARS OF PRODUCTION THE 521 MADE ABOUT 88 HORSE. THE 85-88 MODELS HAD 40 MM CARBS. IN 89 THEY GOT DETUNED BECAUSE OF THE 583 IN THE LINE-UP.

Thanks guys. *If you know of any sites showing these numbers let me know. *

Greygoat, I have a 1986 Plus that when new just destroyed everyone I rode with. *But that was then. **http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/biggrin.gif *Thanks. *Mike

I used to have 86 F Plus. Greatest sled I have ever own!!! Bought used for $1300. When new, the guy took it to HRP and had Brad Hullings do the treatment! Pipes, porting, 580 big bore, 44 carbs K+Ns, the whole works! I bought it, filled it with gas, and took it out on our lake and could smoke the new Wildacats and VMax 750s all day long!! WIsh I still had that old tank!

hello Greygoat, I believe the first production IFS SD was the 1981 (or 1980?) Blizzard 5500 MX

Mxzr
You could be right there,but i rode one of those Blizzards
a freind had and his wasn't much of a sled.Do you think we should count it.
* * * * * * * * * * * GREYGOAT

DYNOTECH HAS STOCK AND MOD HP RATINGS FOR THE 521. THEY ARE INCLUDED IN VOLUME 1 ISSUE 1. THEIR ADRESS IS 8 APOLLO DR. BATAVIA NY 14020. THOSE ARE GOOD MOTORS. MY BUDDY HAD AN 87 THAT CHEWED 650 INDY'S AND WILDCATS. GOOD LUCK.

Hello * *

As far as I know, the ROTAX 521 cc Engine came in four (4) different versions.

they were called as followed:

* 532 * ( Safari Grand Luxe LC *-86 )
* 534 * ( I think this is the same engine as 537, but with Magnesium crank case ! )
* 536 * ( Formula Plus 89-92 )
* 537 * ( Blizzard 9700 83-84 , Formula Plus 85-88 , Formula Plus 500 -90 , Formula Plus-X -91 )

Hp example:

-87 Formula Plus , *"537" * 2*VM40 *= about 95 Hp. / 7800-8000 rpm
-90 Formula Plus , *"536" * 2*VM34 *= about 60 Hp. / 6900 rpm
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Does anyone know which type of RV-disc and jetting that were mounted in these two sleds ? :

* Formula Plus 500 *-90
* Formula Plus X *-91
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Sorry about the grammar and spelling ! * http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/sad.gif

I used to have a 87 form plus it kicked a$$. *What a change from my 78 olympique, lol

Lasse,

The jetting for the '90 Formula plus according to my manual is 250 mains for both carbs and 159 Q-4 needle jets. It didn't say what type rotary but did show the timing. *If you want it let me know.

The '91 Plus X shows 360 mains for both carbs and and *480 P-4 needle jet for the PTO side and 480 P-2 for MAG side. *Hope this helps.

You sure about that 60 hp for the 91 plus X? *Seems way too low to me. *I thought the X model was supposed to have more power than the regular plus but less than the Mach1.

Permafrost - You said it. *I went from a cheetah 5000 to the 86 Formula plus. *To me, at the time, it might as well have been a Mach Z. *

Mike

Blackknight / Mike & Others


All Formula Plus 89-91 had the "536" engine. 2*VM34

But, *As a HO alternative Ski-Doo made this machines in some kind of "LE" models:
* -90 , Formula Plus "500" with the "537" *, *2*VM38
* -91 , Formula Plus "X" *with the "537" *, *2*VM38

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They were never imported to Europe, but still my friend has one of these in his garage !!
We are trying to rebuild it 100%, but we have difficulties to find any tech. specs. on this machines !!!
Thaths why I need help !!

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The Rotax RV-engines with "End" outlet pipe always have bigger basic jetting on the MAG side !!
And the RV-engines with "Center" outlet pipe always have bigger basic jetting on the "PTO" side !!

I think you must have miss read the tech specs.......

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Compared to the ordinary Formula Plus with "536" ( 2*VM34 ) and about 60 Hp. this machines with "537" and 2*VM38 had about 85 Hp !!

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Please, help me out with my problem about the jetting and the RV-disc on this machines.........

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Sorry about the grammar and the spelling !! * http://www.snowmobileworld.com/forums/iB_html/non-cgi/emoticons/sad.gif

Hello Lasse
* I thought i had spec. book on those sleds but just had
* a look and my book only goes to 89 model year.If you
* like go to www.mrrsltd.com/ their e-mail adress is there
* ask for Ken he'll likely help you out.
* * * * * * * * * * * * * * * * * * GREYGOAT

Lasse,

The numbers I gave you are correct, or at least what is printed in the manual. *Clymer Ski-doo shop manual, 1990 - 1995, page 142. *You can find it all over the internet, like amazon.com. *If you want to know more specifics, email me. *Mike