Dirt Bike History 101

[nachtflug]

Originally Posted by PSchrauber

Here the Result:

Eingangsposting:
BMW GS mit Zwillingsreifen hinten, gab es so etwas einmal zum Anfang der siebziger Jahre?

Topic:
BMW gs with dual tires rear, gave it something once in the beginning of the seventies?

Frage:
Hallo, ich habe mal eine Frage an die Gemeinde:
Gab es einmal eine zwillngsbereifte BMW GS, also mit zwei Reifen am Hinterrad, in etwa im Zeitraum zwischen 1970 und 1980?
Ich bin mir selbst nicht so sicher und glaube es persönlich eigentlich nicht, ein Bekannter von mir meint jedoch, dass es so etwas wohl gegeben haben müsste.
Da ich mich mit den BMW Motorrädern auch nicht so genau auskenne, frage ich auf diesem Wege hier die Spezialisten im Forum.

Question:
Hello, I has times a question to the municipality:

There was once a twintire BMW GS, thus with two tires at the rear wheel, in the period between1970 and90? I am not sure and have some doubts, an acquaintance of me mean however that it probably must have given such a thing.
Since I am also not versed so exactly with BMW, I ask the specialists in the forum in this way here.

Antwort:
Bei Gespannen gab es das sicher, ich glaube bei Solo Motorrädern hab ich so ein Bild auch schon einmal gesehen , war aber auf jedenfall eine Bastelei und nix gescheites.

...

Vor allem fährst du in jeder Kurve nur auf einem Reifen nämlich dem Inneren.
Da der ja einen gewissen Abstand von der Fahrzeugmitte hat bildet sich da ein schöner Hebel für alle auftretenden Kräfte. Ich stell mir das zumindest gewöhnungsbedürftig vor....

Answer:
With sidecars there did exists some, I believed with solo motorcycles I have seen a picture once, it was however in any case a makeshift solution and nothing clever.

...

Above all doubts you drive in each curve only on the inner side of one of the two tires. The tire have a certain distance from the middle / center of the motorcycle and therefor this forms a beautiful lever for all arising forces. I could imagine that this behavior will take a long time getting used to it ...

So I hope you are pleased, there might be a picture, but it is not such a good idea to use double tires on a motorcycle. And there should exist a photo too.

As it is not real good idea the interest in this topic was very low and pic's did not show up.

Complete story in German, posted in offroadforum:
http://www.offroadforen.de/vb/showth...fang-der-70-er

À leur satisfaction !!

many thanks for trying my friend. who knows maybe it will get more responses as time goes by. and thanks for posting pictures of the other airhead dirt bikes and providing the information on them.

thanks again!

[Stagehand]

Originally Posted by PSchrauber

But they do look cool:

Cool bikes, these double cylinder monsters, but perilous for Joe average, still dangerous for a good driver even today.

Could be collectable if there would been sold but ae I know this happens very very seldom, there are some replicas around, but the efforts for a replica are very high, nothing of the interna is standard, erverything is weight reduced, optimized for higher performance (power and torque).

Even when you ride a original or a very goor replica remember that still you have to carry along with you about 40kg more than with a standard bigbore 500cm singlecylinder fourstroke!

Be still my foolish heart

[Garthe]

1983 Honda CR 480 R



.

[A_Vasiliev]

Originally Posted by Garthe

1983 Honda CR 480 R

.

Shit, I'd ride that.

[PSchrauber]

Originally Posted by Garthe

1983 Honda CR 480 R



.

How Nice, Jurrasic Park opend again!

Originally Posted by A_Vasiliev

Shit, I'd ride that.

There is nothing embrasing with these creatures, althaught the 83 Honda has a not so good reputation when it comes to power delivery:
first nothing, than again nothing and after third throttel it start ripping awful, until three quart than again not much, if the hit you have got by third throttel has not scared you a lot.

On a big bore single two stroke all personal requirements while riding are limited to:
- getting it started,
- don't get a hanging throttel,
- don't care where and what your rear is doing,
- aim any target where you want to go only roughly.

Beside that it's great fun, sound is very cool.

It's a bike and a bike class itself that separete between real riders and the rest in the world of dirt-bikes. Here you can find out weather you are strong and fearless or a gimp. Everyone should at least have ridden one just for the experience. Best IMHO is to have one and sometimes do a ride with it, just to find out where the borders of ridng or failing can be.

Many older 500cc 2-stroke bikes are in bad mechanical state, pistons and cylinders bearings worn out, heavyly dented pipes, so they have only 50% of the performance left they had when new or with a fresh rebuild.

More please!

[Garthe]

Originally Posted by PSchrauber

More please!

Well, you can come visit my tread...as long as you keep it up with ALL the positive comments...

http://www.advrider.com/forums/showthread.php?t=659435

[A_Vasiliev]

I want to rebuild a CZ 400... really really bad. Always wanted an open-class dirtbike.

[pvangel]

I rode open class for awhile, it's exhausting and not fun....This is fun!



Thats a 490 on my arse(15w) and actually a 125 on either side of me(727)

[PSchrauber]

Originally Posted by pvangel

I rode open class for awhile, it's exhausting and not fun....This is fun!



Thats a 490 on my arse(15w) and actually a 125 on either side of me(727)

I totally agree MX on a 500cc is hard work, but 500cc riding sixdays or endure whatever you call it in the US is cool. For enduro you don't need top speed or all the power like on a MX track, so the bikes are detuned
mine 500cc KTM have a sixdays "package" wich detune it from around 65hp down to 50hp, this makes it much more "gruntier" and controllable, you are just around between 0 to 2/3 of the throttle, it's like floating thru the woods.

I have the MX or "standard outfit too, but as stated already, then it's real hard work. If I'am in a bad mood and have to get rid of build up aggression best way are some rounds with full power delivery and all problems are vaporized.



Comparison MX and Sixdays outfit for KTM 500:



EDIT:
Extract from the part list of the KTM 500 1989,
yellow = MX parts
red = enduro or sixdays model parts
grey = spark arrestor (forest legal equipment for MX model, for the U.S. market)

note:
- closed airbox cover sixdays,
- doubled lenght rear exhaust for enduro/sixdays model
- extra middel resonator between pipe and rear exhaust for sixdays/enduro model
- enduro airbox had an additional opening at the bottom of the airbox, for getting rid of water.

[waspp]

Originally Posted by PSchrauber

As I know they where sold to public, but Frigerio Puch bikes where never a bargain, they did always cost much more than the bikes of the other brands. The bikes where manufactured in the old way, so the production run of each model was very low.

Highest output overall was, - as mentioned already-, under 2000 units in 1980, and this means of all bikes beginning from 50 ccm up to 347 / 440 ccm MC, enduro, cross and some street bikes in one year.

There where also a 175ccm version available. Here is another 250ccm:



And another 250ccm from a different view:


They are dream bikes, so if I would probably have the money and the occasion and still know how to pull the throttle ... how knows what the futur will bring.

I had 2 Puch's a 175 enduro and a 125 both were great bikes and I wish I never got rid of them. From what I remember the 250 was a monster in the hp world and came with dual carbs...is that correct? I managed to pick this up years later and still have it.

[305racer]

Originally Posted by waspp

That is a bike you dont see very often,more porn err....picts please!!

[TLtrials]

Here are a couple of helmet cam videos from our grass track riding this past weekend. I had a welded seam in my expansion chamber split on my PE250, so I got a chance to ride the Bultaco. The 360 Pursang was a lot of fun.


[IMG]

Vintage Motocross/Grass Track from TLtrials on Vimeo.

[/IMG]


[IMG]

VMX 2-13-11 Moto 4 from TLtrials on Vimeo.

[/IMG]

[KansasBob]

Originally Posted by 305racer

That is a bike you dont see very often,more porn err....picts please!!

Meet his younger brother........................................... ..



The motor will back where it belongs soon. 100% original except the PO traded the seat and front wheel with his buddy's 250 H7 when they were both brand new.

[waspp]

Very nice! A year or so newer than mine. I had a heck of a time finding some original bits for mine but its nearly all original.

[KansasBob]

Originally Posted by waspp

Very nice! A year or so newer than mine. I had a heck of a time finding some original bits for mine but its nearly all original.

There are plenty of these "end of the era" Montesa's in Spain, but Very Very few made passage to the US. The 1985 H7 in the photo was imported by a dealer in KY who hung on to the very end. It was his personal bike and he competed with it for two seasons. Life got in the way and he never reassembled the motor after his usual winter maint. He made the conscious decision to "Not" put the motor back together so his kids and grand kids wouldn't ask to ride it. It sat in his shop for the next 25 years until the day he decided to sell it and put the add on craigslist. I paid his asking price without hesitation.

Standard bore, original piston. New rings, and crank seals to be prudent, should be all it needs to spring back to life.