How fast are 125s? and other "micro" bikes

[mysta2]

So what do these things do as far as speeds? I always read in Classic Racer about the small capacity races back in the 60s and 70s and it all sounds very exciting and fast, but I wonder how fast they can actually go. I don't mean to say that you need a whole lot of speed to make a race exciting, but I have a hard time picturing what one of those runs was like.

There was a recent article/review by Alan Cathcart in CR about the Krauser 80. The thing looked awesome with its rivited aluminum frame/gas tank and skinny tires. I'd love to build something like that.

I love how the smaller skinny tired bikes look.

 

[Hoofhearted]

don't know about the Krauser 80 but Ricardo Tormo on a Bultaco 50 was (I read) timed at 128 mph at Zandvoort (I think it was). A "Burt Munro" style streamlined Kriedler 50 was timed at 139 mph in Holland. My Kriedler was, in 1980, timed at 112 mph in the Isle of Man. Robert Dunlop's Kriedler in the same race hi 115 mph. There were some very fast tiddlers back then.

 

[mysta2]

Good god, how's that even possible? Do you just never brake? Is that down the mountain? From as many life on the racing road stories as I've read it sounds like the bikes would often have to last a whole season. How do you get 120mph out of an 80cc machine that has to last more than a few laps? I can't get that out of 360ccs and 6 gears (4 stroke yes... but still that's 4 times the displacement)

 

[Hoofhearted]

The figures I quoted were for 50cc machines and on the flat. No hills. My Kriedler was dyno'ed at 19 H.P. at 16,000 rpm. It could be revved to 17,000 rpm if needed but didn't make any more power. The only time I would do that is in between corners where I didn't want to up shift and then have to downshift. The Kriedler had a life span of 150 miles. The re-build consisted of replacing everything except the crankshaft halves (pressed up crank). A road race weekend could eat up most of those miles. During the season I raced 2-3 weekends a month and would re-build the engine approximately once a month. July always had two road races and two short circuits so the engine got re-built twice that month.

If you go back and check your history you'll see one amazing fact. H. Muller riding a 50cc blown fuel streamliner at Bonneville set a record of 121.700 mph in 1956!! A record that still stands! In 2007 the Buddfab streamliner running a 50cc Aprilla engine in streamliner fuel ran 131.545 mph. I tookmy Kriedler to the Isle of Man for a road race on the Jurby circuit. 4.7 miles of beautiful fast roads. Robert Dunlop won the race at an AVERAGE speed of 72.14mph. I was a distant second at an average of 69.99 mph. Still pisses me off that the timekeepers could'nt have just said 70 mph. That was in 1980 and at the time the LC Yamaha 250s were the hot production racer. The winner of the 250 race had an average speed of 68.70 mph.

Too many people laugh at small capacity machines. They can be made to fly.

 

[mysta2]

I don't laugh at them, and I certianly don't laugh at the guys that can ride them competitively.

my hat's off to you.

I wish there was more of a vintage racing scene over here in the colonies. My parents didn't get around to having me till '80 so I missed all that.

 

[Hoofhearted]

Looking at the photo of the Krauser reminded me of the Isle of Man. Heres a photo from that trip. The orange Kriedler with the lower fairing removed is mine. The green Kriedler is Robert Dunlop's and the really neat monocoque (Minarelli engine) belonged to Don Carlisle. He made it himself in Northern Ireland. It was a fast little bugger.

By weslake at 2008-03-03

 

[pUNKrOCKEr]

i don't know about the other models, but i ride a Yamaha 135cc bike.

i can reach up to about 145km/h..
thats about a few mph short of doing the ton...

but overall, quite speedy...

it just feels like its hurting the engines if i continue for too long...
thats why i dont really speed. its safer.

 

[gord]

I don't laugh at them, and I certianly don't laugh at the guys that can ride them competitively.

my hat's off to you.

I wish there was more of a vintage racing scene over here in the colonies. My parents didn't get around to having me till '80 so I missed all that.,,,,,,,,,,,,,,,,,,,,,,The VRRA here in ontario is one of the biggest m/c vintage racing clubs in the world,you never know what will come out at Mosport but there is usually rare and exotic somewhere in the pits Check it out in August,there will be a few DTT members racing there

 

[Ton Up Dave]

My first bike was a Honda 50 Supersport .It was a four speed and it would do 70mph...flat out lying on the tank
Thrashed the hell out of it..seized it once through lack of oil ,no prob started again.Loads of fun.

 

[mysta2]

Ontario's not the colonies

I'm in Texas