Critical Mass Yet Again - ‘90 Gen1

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😂

Lol, I think you’re being a bit harsh. I had to look up plonker, but laughed when I saw what it is. Had a pretty good idea from the context, but checked just the same.

And yes, I am a forum guy. I have belonged to countless different ones over the last couple of decades. From camperMobile, to guns, various automobiles, astronomy, fish, motorcycles and more. I really think this one is about as tightknit as any I’ve ever been part of. Not to mention a gold mine of information on the Vmax. And hair.

Thanks to all for the discussion and working through this particular float issue. There may still be some BS ahead of me on this bike, but hopefully carburetors won’t be part of that.
 
I had an OSSA 250cc ISDT bike, one of the great bikes from that company. They also made a trials bike called The Plonker. I've never-owned a trials bike, but they aren't tuned for power, it's torque and light weight. Dig that rear sprocket! They also used chain control as-in idler wheels to maintain chain tension for greater bike control. There was a lot of ground clearance, and seats were just something to use between sections on the trial course, as most of the time, the rider is on the footpegs. The OSSA has a particularly-well-stuffed seat, atypical of what most had. Yamaha had a trials bike the TY250, first released in 1973, one of my local acquaintances had one. It was a pretty bike. The Yamaha seat is more-typical of the breed. In the mid-1970's, all the Japanese manufacturers had trials bikes, it was supposed to be "the next big-thing" in motorcycling, but it never took-off. Frames on enduros were often double-loop downtubes, while trials bikes often had single tubes for less-weight, or smaller-diameter double-downtubes, smaller than normal suspension components, and tucked-in exhausts to allow the calisthenics/gymnastics a competitor would engage-in to maneuver the bike over obstacles that would be very-difficult for a person on-foot to traverse.

The Kawasaki KT250 is typical of the breed, lightweight, tuned for torque and a minimal seat. The one pictured below has a small rear sprocket, which would be replaced with a much-larger one in competition.

1970 OSSA Plonker Observed Trials Bike - National Motorcycle Museum (nationalmcmuseum.org)

Another Revolution Heard From – 1974 Yamaha TY250 | Bike-urious (bike-urious.com)

Bonhams : 1976 Kawasaki KT250 Trials Frame no. KT2-06251 Engine no. KT2E 006295

OSSA Plonker trials bike 1970.jpgYamaha-TY250-1974.jpg
Kawasaki KT250 trials 1976.jpg
 
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Worked with a fellow some years back from Scotland who was a huge trials rider and enthusiast. Requires a crazy amount of talent to be even moderately successful. For folks who really don’t know what it is, let’s just say it ain’t easy. And for the record, no, you cannot put your foot on the ground during competition.


Queensland Trials
 
Worked with a fellow some years back from Scotland who was a huge trials rider and enthusiast. Requires a crazy amount of talent to be even moderately successful. For folks who really don’t know what it is, let’s just say it ain’t easy. And for the record, no, you cannot put your foot on the ground during competition.


Queensland Trials
Watched your video, great stuff dude. The terrain they are on in Australia is equally natural to Scotland over and over again, I think that is why we have so many trials riders here.

Tried this stuff very low level when I was about 20, loved it but just never had the money to get involved, so had to make do with my Z650 and pedal bike instead. They are damn expensive for the higher level trials bikes. Infact I still go out on my mountain bike most days and much prefer rough routes to the smooth, I'm 60 this month and still as strong on a pedal bike, although I tend to try stupid things and broke my wrist last year, maybe it's best for the health service here that I never went to trials riding.
 
(Amazing the tangents we go off on due to all the triggered topics coming from FM's brain)

Sheesh. Never a dull moment.

Stay tuned for further 90 Gen1 exploits. Looks like my needles will be here today rather than the 6th! Hopefully, the drama is behind me (except for fork seals).
 
(Amazing the tangents we go off on due to all the triggered topics coming from FM's brain)

Sheesh. Never a dull moment.

Stay tuned for further 90 Gen1 exploits. Looks like my needles will be here today rather than the 6th! Hopefully, the drama is behind me (except for fork seals).
I’m getting more excited every day, and it’s not even my bike.

When F_M comes online I instantly open my online dictionary. The vast related/not related diverse knowledge he has is incredible, he also must have a memory like an elephant to pull this stuff out of thin air.

keep posting dude as it’s a very interesting subject.
 
The Spanish manufacturers have always supported the trials sport. Newer manufacturers like Gas Gas and Beta emerged, while in the 1960's and '70's Bultaco and OSSA were big names in trials manufacturers, there were others.

The Bultaco and OSSA importer was in Schenectady NY, his name was John Taylor. He also had Full Bore as a brand, and that was a line of products from replacement parts for dirtbikes, to oil, to clothing for off-road riders. The Full-Bore motocross boots were famous as they had aluminum plates riveted to the fronts. Wearing a pair of these, and showing-up with a European bike like a Bultaco, an OSSA, or a Maico immediately identified you as someone serious about having good equipment, and hopefully, the skills to use it in the method for which it was designed.

Friends of mine bought-out the business, and over time they liquidated the stock. I bought from them a Full Bore enduro jacket which I still have, and wear occasionally. It's from the days before jackets had 'inside' armor. It has voluminous pockets inside and out, because competitors would often carry spare parts on-them, like innertubes, so you needed storage space. Ever-see an old video of an ISDT racer changing an innertube? It's amazing how-fast they can do it.

One of the things that was in the inventory was an OSSA **** Mann Replica (OSSA-DMR). You whippersnappers should look up **** Mann, Steve McQueen wished he was as-good as **** Mann on a motorcycle. The **** Mann Replica was brand-new, it was an entry ornament at the office. That was a great short-track machine in its time, comparable to the Bultaco Astro. The OSSA trials bike was designed and campaigned by Mick Andrews.

Below is a description of an advanced design conceived in the USA before Charlie Manson's followers visited Sharon Tate and the LaBiancas, and the Hells' Angels offered to be the security detail for the Rolling Stones at Altamont Raceway Park in California, east of San Francisco.

A failed attempt to manufacture a killer enduro bike was the Yankee Z, a 500cc two-stroke parallel-twin which used the OSSA 230cc Pioneer enduro top-ends on a common bottom-end. Eventually, the design used a full 250cc design, for the two pistons, to make it a true 500cc. An interesting feature was that the pistons could be made to fire together, or on alternating crankshaft revolutions. It had a six-speed gearbox where low gear was capable of being rendered unavailable to meet racing regulations of the day.

Remember **** Mann? He designed and built the chro-moly frame for it. Those of you who were into dirtbikes in the 1960's and '70's will recognize the wheel rims manufacturer, Akront, a Spanish company which manufactured shouldered rims that were on seemingly all the best bikes of the day. Of-course Akronts were used on the Yankee Z.

Smith & Wesson made the forged triple tree for the bike. The downtubes were as-big as the '85-'89 VMax. You can't say that John Taylor did things on the cheap. It also sported a Kelsey-Hayes disc brake-in the rear! The front was a traditional drum. In a concession to saving weight the axles were hollow.

The Yankee Z was just too-heavy to be successful in the type of use to-which it was being subjected. Fueled, it was > 350 lbs. Detuned motocross bikes which in motocross use had to be ballasted to make minimum weights, were used for enduro use, and they were 75 lbs less weight, which means the operators were wrestling around much-less machine. The under the bike motocross pipes were exchanged for higher pipes, sometimes 'through the frame,' to slim the design. Gas tanks needed to be bigger/heavier, and additions like lighting and switchgear added weight. Still they were single-cylinder designs and that-alone meant less weight to control. You might call the twin-piston Yankee Z to be "too-much of a good-thing."

One of my friends here in So. Florida tried to roadrace a Yankee Z. The vibration running at the high rpm's necessary to make power just shook-apart things, and caused metal fatigue to the point of failure. He tried thread-locker, he tried safety-wiring, it was just the wrong use for that particular engine design. He was a successful campaigner in AHMRA and he had a Shell-built engine Yamaha 650 twin which won races. The Yankee Z was a disappointment for him. Here's a pic of one at the St. Augustine FL classic bike show usually held in late May every year, at the World Golf Village. My buddy and I didn't attend last year (COVID) but we're thinking that we might be able to make it this year. This year, it's moved-up to April 24.
Home | Riding into History It's a great event, lots of interesting bikes. An acquaintance of ours, Don Bradley, who was an enthusiast, a machinist, and a motorcycle dealer, was also an artist. He would design the show posters, works of art themselves (I have many of them). Some are ****! He had an Indian Chief and a Vincent Black Shadow, and he would ride them across states, and show them regularly. Unfortunately, he's gone now, his daughter tries to keep his memory alive. Don Bradley | Riding into History

YANKEE Z 500cc twin.jpgYankee-OSSA 500 cc twin 2-stroke.jpg
Don Bradley BSA Riding Into History poster.jpg
 
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OMG I see now why you now and then post a picture of a girl in black shiny tight clothing, its obviously art ;)

we get Wayne on the telly here too, very interesting guy.

what a read though, enjoyed that.
 
Runs pretty good, but there’s a little more excitement on the top end of cylinder number four than I would like to hear. May have to pull the valve cover. Needs gaskets anyway. Haven’t even synced the carburetors yet and it already runs pretty darn good.

Will button everything up and take a maiden voyage tomorrow. Hoping for solid second gear.
 
"He spent a lot of time in the UK so enjoys riding in wet conditions" Cheeky ******* - I'll let you know it does stop raining at least twice a year o_O

... or you can do similar stuff but without the engine:
Danny MacAskill’s Wee Day Out - YouTube
That video is brilliant, i’m a great fan of Danny, clearly the best + a bit more. I started doing some of this stuff on a pedal bike at the age of 9, its damn difficult to even do a fraction of what he does. We would build ramps and fly off them, rattled my goolies on the bar a number of times, and put a scar on my throat by going through someones garden and catching on a washing line. Damn dangerous, he just does this with ease.

1 sunny day for us so far this year.
 
I like the outtakes, it shows it's not always, "nailed-it!" Note how-often he maintains a grip on the bars as he comes-off the bike, even as he parts-company with it, and then releases.

The succeeding video I watched had me worn-out at eight minutes, then I saw it's 39 minutes long! The aerobic conditioning these guys have is incredible.

 
I like the outtakes, it shows it's not always, "nailed-it!" Note how-often he maintains a grip on the bars as he comes-off the bike, even as he parts-company with it, and then releases.

The succeeding video I watched had me worn-out at eight minutes, then I saw it's 39 minutes long! The aerobic conditioning these guys have is incredible.


That's a great video, watched it with great interest, thanks.

My wife's family have been looking for a trial pedal bike stunt course as a special gift this month on my 60th. This was at my request and they could not find one at all for trial stuff. Surprised me, but there you are. I think it's a Scottish DNA thing this level of madness. "Better to burn out than to fade away", Highlander.
 
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