That’s really cool looking though.
was pretty quick too -
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There are several legends about the real performance of these, some I suspect were fomented by Parilla himself, some by cult followers, some may actually be real as you see above. I believe in an interview Achille was saying these engines caused the demise of the rotaries, a cut above everyone else, super fast out of the box (“you could remove 500g of aluminum and it will go slower than a stock one”, with a couple of different discs you covered pretty much every tuning need).
I’m skeptic, but we shall soon put it to the test. Somebody here said “believe nothing, test everything”. So here we go, dove into the deep end.
vs
I’m super busy with work so the rebuilds will take time, but I got help from Italy to work on some of this stuff, it’ll be fun.
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The 90s where awesome for different ideas at the top level, so many different chassis designs that where drastically different. Anything to gain an edge.
most manufacturers made inboard drive motors to get a more direct flow into the cylinder as the sprocket wasn’t in the way so the carb could be on a greater angle, italsistem just went crazy and put the valve on the front.
Rotax DSD-L
Rotax DSD you can see that the carb flange is alot flatter
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Yes you can clearly see where they were finding power. Trying to get as much charge as possible by optimizing flow, so you can either try and get a favorable angle of entry on the side (by moving the pinion on the left DSD/DSE, but the crank is still in the way) or moving the intake directly centered in between the two crank halves (Ital). I believe I’ve seen a shifter rotary prototype too, where they moved the disc in front for the same reason
On the standard ones I’ve seen some aggressive profile of the liner to help channel the flow, trying to achieve the same result
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What Era is this engine? 80s?
those engines are 2001 homologation I believe
Wow they look like your old dds.
Bringing this back from the dead……
Here in the USA when I was a young man I ran what we called Super 100, ROW may have called
It Formula A or super national.
100cc rotary valve engines direct drive, Rotax DS series engines were the dominant one.
Watching Alan’s YT I have learned there are a few DS series engines DSA, DSB etc, can someone tell me the difference between them?? I did not know this until recently.
Would love to find one of these and re live my younger years, what an amazing time it was!!!
Do you have more info on super 100?
Rotax naming went like this:
DS: Rotary
VM: Reed
PP: Piston port (not 
sure on this)
Then you had the lettering which corresponded to the homologation period. The model years are off the top of my head so you’ll have to give me a bit of grace on those.
A (I think 85-87). Parallel fin head without Rotax on casting.
B (89-91) Parallel fin head with Rotax on casting.
C (92-94) Radial fin head without cylinder shrouding.
D (95-97) Radial fin head. Square, angular cylinder shrouding.
E (98-01) Radial fin head, more rounded, modern cylinder shroud.
So, DSD is a rotary from 95-97.
VME would be reed 98-01.
Within these there are some variations. For example I think the DSC and DSD had 1,2 and maybe even 3 variants. Main different being oval vs bridged exhaust port.
One last think is the -L designation which is for left side drive. Or inboard drive. For example DSD-L.
Hope this helps.
There’s always confusion around the Rotax because of the nomenclature and homologaiton extensions. Double check homologation years. There’s always been a lot of confusions around the Rotax line of engines in this period with a lot of misidentificaiton. I might have a fuel detials wrong, but it is as follows:
Rotax R100 - 1983
- Radial head, it may have been updated before the next homologation. Can’t remember.
Rotax DS100 - 1986
- Parallel fin head.
Rotax DSA & DSB - 1989
- Parallel fin head.
- Like the DS100 the DSA doesn’t have the fins braced at the rear, however the DSB did have this update. Presumably because they had a few barrels left over from the DS100 and they could throw the updated port liner in them and shift as the DSA.
- Extra ports, can’t remember which. I think it’s the added auxiliary exhaust ports.
- The crankcase changed with the bracket for the coil so it was on the outer side rather than centrally located. Same for DSB and DSA
Updates
The DSB 90-A was an updated version of the DSB with wider studs to accommodate a larger exhaust port.
The DS100 was rehomologated in 90/91 with the rear fins braced. This often gets confused as a DSB because of that.
Notes
I believe in period the lack of Rotax stamp on the head of the 89 homologations, despite them being on the actual produced engines caused regualtory issues, nothing serious, but I don’t have specific anecdotes to hand.
Some engines are Frankensteins so this isa problem occasionally. The difference between a DS100 and DSB/DSA should always be assessed via porting.
People think the DSA proceeded the DSB but they were homologated the same year. The DS100 often is mistakenly called the DSA
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When I first started karting in the 90s, I started on a spec 4-cycle class that used a sealed Tecumseh (H50?) engine. This was supposed to be a “Rookie” class before moving into the Briggs flathead or Yamaha KT100 sportsman classes, but we quickly found the Sportsman Tecumseh was faster than the Sportsman Briggs flathead (with purple restrictor plate) and was nearly as fast as the Sportsman Yamaha class.
I had heard that these engines may have been more popular out in the West in the mid/late 90s, but they never really caught on in the Midwest and disappeared after a couple of seasons and we moved into Yamaha. I know some places ran open/modified versions (Tecumseh STAR?) and they may have had a little more popularity in the dirt scene for a time.
James, IKF (possibly WKA as well, long time ago) adopted “super 100” in 88 or 89 after a short spell of trying the Formula K class, Komet 135cc rotary valve direct drive, I’m sure you know, it was THE class in Europe. At 14 I was running that class and it was amazing!! This went away and Super 100 took its place. I was pretty sure we ran the DSB Rotax, but after watching some of Alan’s videos heard there were a few variations. From your list DSB correlates with the years, parallel head fins but ours had no branding on the outer fin but did have the Hezemans plaque.
I know Hezemans was involved with the development of those engines, if I remember correctly.
This shot was the 1990 IKF Grands at Oakland Valley. I’m #85. You can see the engine a bit in the pic. From what I remember everyone ran the Rotax.
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