40 replies to this topic

[SADBATCCM]

The Rotax tandem twin
In the early 80s.... this motor was developed for cotton ccm Armstrong?? From what I remember it was a skidoo motor that was transplanted into a bike frame!!

please add your com's

Edited by SADBATCCM, 11 June 2010 - 23:16.

[MoMurray]

The tandem was never a Ski Doo motor, although Rotax has been owned by Bombardier, makers of Ski Doo, Sea Doo and CanAm since 1971. The tandem was a purpose built road race engine and although difficult to set up, once it was done right, it was mighty. Very different from the TZ that was popular at the time and that was the root of most of its negative press - the fact that many people tried to tune it as a TZ and it never worked. I spent a lot of time fettling these motors, ever helped build an off road desert racer around one and I was and am very fond of this motor.

Mo.

[SADBATCCM]

The tandem was never a Ski Doo motor, although Rotax has been owned by Bombardier, makers of Ski Doo, Sea Doo and CanAm since 1971. The tandem was a purpose built road race engine and although difficult to set up, once it was done right, it was mighty. Very different from the TZ that was popular at the time and that was the root of most of its negative press - the fact that many people tried to tune it as a TZ and it never worked. I spent a lot of time fettling these motors, ever helped build an off road desert racer around one and I was and am very fond of this motor.

Mo.

Did Jon Ekerold get a full works motor for the 82 TT a magnesium unit?

[philippe7]

The tandem was never a Ski Doo motor, although Rotax has been owned by Bombardier, makers of Ski Doo, Sea Doo and CanAm since 1971.

What probably confuses people is that the Sea-Doo's were powered by 2-stroke inline twins very similar in design to the motorcycle engine - but of a larger capacity, I recall around 1000cc on a Sea-Doo I had ? Same engine was used for early ultra-light aircraft , with Rotax branding, I'm sure . Of course, most of those Sea-Doo wet bikes and Ultra-Light flying things are now powered by ( similar in design ) 4-stroke inline twins .

Before the Rotax inline twin appeared in GP races ( was it originally on the Cotton, or the first Aprilia, or a self-built German or Austrian bitza ?.... ) I am sure I have seen a picture of a "Can-Am" branded road racer using a "bombardier" two-stroke engine , in northern america. As early as late 70's maybe. Not sure it was the same in line watercooled engine as the Rotax, though

[MoMurray]

What probably confuses people is that the Sea-Doo's were powered by 2-stroke inline twins very similar in design to the motorcycle engine - but of a larger capacity, I recall around 1000cc on a Sea-Doo I had ? Same engine was used for early ultra-light aircraft , with Rotax branding, I'm sure . Of course, most of those Sea-Doo wet bikes and Ultra-Light flying things are now powered by ( similar in design ) 4-stroke inline twins .

Before the Rotax inline twin appeared in GP races ( was it originally on the Cotton, or the first Aprilia, or a self-built German or Austrian bitza ?.... ) I am sure I have seen a picture of a "Can-Am" branded road racer using a "bombardier" two-stroke engine , in northern america. As early as late 70's maybe. Not sure it was the same in line watercooled engine as the Rotax, though

Correct the Can Am was a 500 in line triple (across the frame) as far as I recall. Jim Allen raced one. Sea doo engines started out as 580s then 650s, 720s, 785 before going to direct injection or 4stroke. Big difference with Sea Doo/ SkiDoo and the road race engine is the water & snow applications did not have gearboxes. The tandem was a unit construction (later got a cartridge gearbox). Single ignition system which meant timing the two cranks very precisely. I shaved a lot of woodruff keys! There was a wasted spark at BDC with the motoplat so many folks thought to turn one cyl 180 degrees but it never worked.

This was the engine in the carbon fiber Armstongs as well as the Cobas, Aprilia, EMC, Waddon and a host of others in the mid eighties.

Mo

[philippe7]

Correct the Can Am was a 500 in line triple (across the frame) as far as I recall. Jim Allen raced one.

I did a google search without any real hope and to my surprise this turned up....exactly what we were talking about !
http://www.classicca...com/canam22.htm

Sorry for drifting away from the Rotax tandem

[philippe7]

OK, I'll drift away from the topic for one more post only, honest....but look what I've found ! OK, not very clear, the page was un-copyable so I had to fiddle around with screen captures etc...but the material is good ! That's definitely the racer I remember seeing a picture of...
By the way Mo, it seems that it was a twin, apparently....

[Coupe Kawasaki]

I haven't spent long on this but here's an idea of what's available today http://www.startingl...p;productID=652 cheap go faster kit I'd say.


I remember that Can Am vaguely Mo/Philippe they never gave two strokes a chance with the emissions and killed any development on the road which is daft as there are thousands of other two stroke motors used for all sorts of things They have been used in stunt quads and stuff (over 200 hp!) Mark Jordan at Team Sparrow was thinking of running one in the open class a few years back



David

[Coupe Kawasaki]

Thanks for all of that info there Philippe, it's re-kindled an interest The Norton Rotary was used in target drones and may still be along with the Rotax which is used a lot in Microlight applications



Dave

[HEMEYLA]

1984 Can-Am 250 production racer build by Armstrong with Rotax tandemtwin engine ........... click ...... and more ........... click.

Edited by HEMEYLA, 12 June 2010 - 04:21.

[Steve O'Brien]

About 1987-88 I read about a guy who had made a bike using the Rotax twin he lived on the outskirts of Kirkby Liverpool, the bike was unusual in the fact that it had leading link forks but the steering was done by what looked like thick brake cables he was looking for someone to finish it I did offer but I never heard anymore about it.

[exclubracer]

OK, I'll drift away from the topic for one more post only, honest....but look what I've found ! OK, not very clear, the page was un-copyable so I had to fiddle around with screen captures etc...but the material is good ! That's definitely the racer I remember seeing a picture of...
By the way Mo, it seems that it was a twin, apparently....

What an interesting article, many thanks Philippe.

Such a shame that many of these snowmobile-based projects never came to much in the day, many of them would have caused a stir methinks, like the belt drive Kohler for example.

Found a piccy...

http://www.eurospare...cs/monotrk1.jpg

Some interesting stuff on this site:

http://www.eurospares.com/graphic2.htm

Edited by exclubracer, 12 June 2010 - 19:18.

[SADBATCCM]

Thanks’ gang for all the interesting com’s
Didn’t get to the bottom of this one!!
Did Jon Ekerold get a full works motor for the 82 TT a magnesium unit?
Having spent many a happy hour in the back of the Rotax van measuring port heights to get a matching pair strange how much difference there was in there castings... or bore coatings

[Coupe Kawasaki]

That Eurospares site is great Mick, loads of good stuff for everyone..brilliant I was looking at the frame building on there..very good



Here's a snowmobile motored quad dragster...just for the sound it's worth it

[exclubracer]

That Eurospares site is great Mick, loads of good stuff for everyone..brilliant I was looking at the frame building on there..very good



Here's a snowmobile motored quad dragster...just for the sound it's worth it

Yes it was a good find David, Brian Flack's bike gets a mention on there also.

[Ray Oldam]

Philippe,

Hi and thanks for the interesting posts - I don't remember the 500 twin but it would have been interesting to see it raced. The four stroke Rotax now used in most microlight (ultralight in America) aircraft is the 912, which, confusingly, is a 1300cc engine! It is a horizontally opposed four, with water cooled cylinder heads, linked to a reduction drive gearbox, and puts out around 80bhp, which may seem low but they are designed for continuous running at full power for long periods. Here's a photo of an aircraft I used to own a share in, which shows the engine. Before the 912, Rotax produced a series of two stroke aircraft engines, the 377, 447 air cooled twins, and the 462 and 582 liquid cooled versions, but all the two strokes would drink fuel, limiting the range. The 912 is a great engine, and a huge improvement on the old two strokes.



All the best.

Ray

Edited by Ray Oldam, 13 June 2010 - 18:13.

[SADBATCCM]

Well this is how i think this motor should be used

Edited by SADBATCCM, 13 June 2010 - 18:30.

[sidecarracing]

various Rotax 500 twin racers on this interesting blog:

http://jlmeccanica-rotax.blogspot.com/

[sidecarracing]

I think this is where it all started with Rotax engined motorcycle race bikes:

http://www.lippitsch...amily/heinz.htm

This is Heinz Lippitsch, one of the Dipl.Ing of the Rotax factory who in his spare time raced quite succesfully.

He developed and also raced the bike, I think later Heinz Kriwanek was drafted in as he was a better rider.

Kriwanek was 5th in the 125 world-championship of 1969.

Edited by sidecarracing, 13 June 2010 - 19:04.

[SADBATCCM]

various Rotax 500 twin racers on this interesting blog:

http://jlmeccanica-rotax.blogspot.com/

my god look how thin the barrels are


the first big bang motor!!

Edited by SADBATCCM, 13 June 2010 - 19:04.

[SADBATCCM]

and this one with a funny disc

[Coupe Kawasaki]

My mate used to work in the race dept at AP and did the Rainey brakes etc After that pic though I think...he's on FB I'll see if I can get something out of him Tim


Here's a Yamaha snowmobile motor from 1968 It's a YR1 350 (tr2b) without the gearbox essentially. The link is fantastic if you want a parts fiche for almost all of the old Japanese (USA) models . I use it all of the time for cross referencing parts to see what fits what..essential if you don't want to throw money away


http://www.powerspor...rand/parts.aspx

Looks like you'll have to search it as the link works that way

David

Edited by Coupe Kawasaki, 13 June 2010 - 22:02.

[Coupe Kawasaki]

Take a good look at an RD 500 twin in Aprilia RS250 chassis here

http://www.twostroke..._RS500_2008.htm

David

[Terryt]

Thanks’ gang for all the interesting com’s
Didn’t get to the bottom of this one!!
Did Jon Ekerold get a full works motor for the 82 TT a magnesium unit?

Yes he did. I had a bit to do with the ´82 Armstrong TT effort and I think he might have won the race had he had a production Rotax motor. He was quickest in training by quite a margin, but in the race he was never going well due, it was thought at the time, to the casings flexing which ultimately led to his retirement due to crank bearing failure on the fourth lap while lying second to Tonks who was on the Randle bike with standard casings. He had never sat on the bike before the TT so we obviously thought the magnesium engine was an advantage after his more than impressive practice times. They say you live and learn
Regarding Ekerold, I´m not sure anyone impressed me more than him on the Island. Despite his relative inexperience, he was so fast and smooth, and he brought the GP style to road racing. Lovely guy to work with as well.

[yslandvoarder]

Hey,
Just found out Motorcycle Racing Nostalgia. I'm 50-plus en for more than 30 years visiter of many GP's and other races. It all started with a race at Hengelo (Holland)in april 1980. This trip I made to see the Honda 400cc twin cup. My first little moto I HAD...
The most spectacular race that day was the 250cc race. Between the Dutch and (some Belgian riders) all with Yam-TZ there was a certain Chas Mortimer. He came over to test the cotton-Rotax 250cc racer and won the race quite easily What a rider and what a bike!
The Belgian riders in 1981 which drove Rotax-powered bikes (gp 250) did quiet well also. Jean-Marc Toffolo, Etienne Geerard both on Armstrong-Rotax.
It was nice to see
Was Chas Mortimer only test-rider in 1980 (cotton-rotax) and if so, which UK-rider drove the cotton 250 that year?
Thanks! Sorry for my English.

[bobness]

UK riders on Cotton Rotaxes in 1980 included
Steve Cull
Clive Horton
Graeme McGregor
Steve Tonkin

There will be more I'm sure.

[Terryt]

Yes he did. I had a bit to do with the ´82 Armstrong TT effort and I think he might have won the race had he had a production Rotax motor. He was quickest in training by quite a margin, but in the race he was never going well due, it was thought at the time, to the casings flexing which ultimately led to his retirement due to crank bearing failure on the fourth lap while lying second to Tonks who was on the Randle bike with standard casings. He had never sat on the bike before the TT so we obviously thought the magnesium engine was an advantage after his more than impressive practice times. They say you live and learn
Regarding Ekerold, I´m not sure anyone impressed me more than him on the Island. Despite his relative inexperience, he was so fast and smooth, and he brought the GP style to road racing. Lovely guy to work with as well.

Thought I´d just add this shot of Jon at Rencullen on the works Armstrong in the ´82 TT.

[Coupe Kawasaki]

I see what you mean about being at home on the circuit...super shot Terry


Daisy

[gmwzorro]

Derek Huxlley used to be the works Cotton rider in 79 on I think a v twin
remember it used to be a pig to start and also remember him almost
catching Kork Ballington who was on the works Kawasaki after the Cottons
usual poor start at Oulton in 79

[gmwzorro]

Clive Horton Cotton Donington 80

[Leif A Nielsen]

The Rotax tandem twin
In the early 80s.... this motor was developed for cotton ccm Armstrong?? From what I remember it was a skidoo motor that was transplanted into a bike frame!!

please add your com's

Hi,

Here is a few pictures of my Nico Bakker Rotax, picked up the frame in Holland 1981 used it 1981/82 and then sold it, got the remains back a few years ago, been sousing parts for a while now, hope to have it done for next season.


-Leif

[fil2.8]

Looks promising , very nice , Leif

[roadshop]

Looks promising , very nice , Leif

Hi, Leif

Did this bike reach Denmark yet?
Classic racing in midtown Aarhus next weekend, motorcycle parade class as well!

Poul Erik

[Coupe Kawasaki]

I can see why you guys like this so much...the motor is very compact and slim.....nice Leif

[SADBATCCM]

Thought I´d just add this shot of Jon at Rencullen on the works Armstrong in the ´82 TT.

Thanks TerryT
Thought Jon had a works motor!! But not a works bike, that motor at the time was supposed to have 10% more power hence the quick times!
That‘s not getting away from the fact that he was a very quick!! Met him on several occasions always seemed to me as very hard faced just like Graeme McGregor !!

[SADBATCCM]

My mate used to work in the race dept at AP and did the Rainey brakes etc After that pic though I think...he's on FB I'll see if I can get something out of him Tim


Here's a Yamaha snowmobile motor from 1968 It's a YR1 350 (tr2b) without the gearbox essentially. The link is fantastic if you want a parts fiche for almost all of the old Japanese (USA) models . I use it all of the time for cross referencing parts to see what fits what..essential if you don't want to throw money away


http://www.powerspor...rand/parts.aspx

Looks like you'll have to search it as the link works that way

David

Well Daisy
The pic of the front brake was at snetterton just before the British GP in 82, this was the first time we used it.
The first one’s as in pic were cast steel, this caused big problems!! due to the weight round the rim, just like a spinning top the brake would work super in a straight line but on fast corners the thing would not turn in, causing one or two off’s. Later ones were ally with steel outer this seemed to stop the above problems

[Terryt]

Thanks TerryT
Thought Jon had a works motor!! But not a works bike, that motor at the time was supposed to have 10% more power hence the quick times!
That‘s not getting away from the fact that he was a very quick!! Met him on several occasions always seemed to me as very hard faced just like Graeme McGregor !!

Not sure how you arrived at the extra 10 %, but the whole object of magnesium was to reduce weight, not increase power. The bike was a full works jobbie, so maybe weighed a bit less than the standard one, but that was sort of cancelled out by the fact Jon was quite a big fellow and weighed a good few KG´s more than Tonks, for example. The one or two kg´s the magnesium motor saved was neither here nor there IMO.
Hard faced? Definitely. After all, he was a professional and, like Graham McGregor, wanted to win. Nothing wrong with that.

Edited by Terryt, 19 June 2010 - 20:10.

[Leif A Nielsen]

Looks promising , very nice , Leif

Thanks Phil, can't wait to finish it

Edited by Leif A Nielsen, 20 June 2010 - 08:58.

[Leif A Nielsen]

Hi, Leif

Did this bike reach Denmark yet?
Classic racing in midtown Aarhus next weekend, motorcycle parade class as well!

Poul Erik

Hej Poul Erik,

Half of the bike is in Denmark, so it won't be ready this year, I do not have all parts yet, but I am getting there SLOWLY

Hope all goes well in Århus

-Leif

[fil2.8]

Thanks Phil, can't wait to finish it

Neither can we..................................................................

[mba21]

Hi,

Here is a few pictures of my Nico Bakker Rotax, picked up the frame in Holland 1981 used it 1981/82 and then sold it, got the remains back a few years ago, been sousing parts for a while now, hope to have it done for next season.


-Leif

Leif that looks fantastic.................