Trials Australia Forums

Rod wrote:Hey David, hope you didn't pay too much for that rust bucket, obviously Ossa, fork bottoms and barrel to carb connection make me think '74 MAR mk2.

I'm in agreement as MK2 Rod. Shoulderless rims are another ID for Mk 2 too. I'm yet to measure the swingarm length.
Frame and engine 222xxx. Same first three numbers as my Mk 2 ride bike.
I paid a price that both seller and buyer were happy with.
I bought it for the motor parts and am trying to decide whether to sell the rest as one thing or part it out.

tat ty wrote:As a kid I would remove the front wheel and drop the bars down and could tuck the TY250A into the rear of my mums little Renault 12 station wagon.

My friend who bought this TY250A is currently having his ute repainted so only had the Corolla but was hanging out to get hold of the .
Did your TY250A fit standing up in the back of the Renault 12 with the front wheel out? It does look like a nice high load space.
I know French cars are amazing for usable space, having tested how many human bodies can fit in the boot of a Peugeot 504 sedan.

Yes David, I'm pretty certain it was upright. Was a bit of a struggle dragging the forks across the floor and the seat backs.

It was only thinking of this that I remembered the system of the modified hub on aluminium channel. It was such a simple system.

My Dad had a ute, so the Renault only came to the fore occasionally.

Hi Everyone,

David Lahey wrote:I could not resist buying this parts bike today.
Kudos for people who know what it is.

Way too easy David, Spanish Rust You have inspired me to look for some Spanish Rust of my own so back to the Emporium:

That one's tricky Greg. I hope this is a quiz.
There's some things that don't normally go with some other things, as Mark Keenan would say, "a Legion"
I'll wait until I'm sure it's a quiz before having a go

M85 ??

sherpa wrote:M85 ??

I was thinking M85 (or M99) too but if it is one of them, shouldn't it have tapered top fork tubes and parallel front hub and mudcatcher front rim?

I've started working on a series 2 250 MAR motor and thought it would be fun to share some weird things about the 5 speed motor.
It took a few days to get the engine cover off because one of the screws was stuck in place. Luckily I'm a patient man and multiple applications of heating and cooling and WD40 over the three days got it to the point where an impact driver could move it.
The piston was stuck too but over the same three days, WD40 and persistence eventually got the piston moving in the bore. I carefully used an adjustable two-pin wrench in the holes in the magneto flywheel to move the piston without overloading the crankshaft.
This is the primary drive side of the motor.
There are no kickstart idler gears because the kickstart shaft drives the gearbox rather than driving the clutch basket. and of the era are also like this and it means that if you pull the clutch in the kickstart won't drive the motor.
The double-row primary drive chain that chose to use in their motors is the same chain as used in some old BMW car motors as a cam chain, so it is still easy to source new chains in 2022.
The thing I'm pointing at is a device that absorbs driveline shocks. It allows for the working components of the gearbox to have a much easier life than if it wasn't there. There are two axial cams that sit against two opposing axial cams and are held together by the helical compression spring. 1970s Japanese trials motors also have a device that does the same thing in the form of rubber cushions hidden in the rear of the clutch basket, mechanically isolating the clutch basket from the clutch gear. This device is mounted on a taper on the crankshaft and a special puller is required to get it off the crankshaft to change the crank seal or pull the motor apart.
The kickstart shaft is the one with the big diameter spline. The smaller diameter spline in the photo is for left side shift. The shift shaft goes right through to the other side so you can use the bike either left or right shift, or both. Standard for the MAR is left shift, right brake.

I forgot to mention the kickstart return spring last night. The "clockwork" spring looks unusual but works very well

Greg Harding wrote:Hi Everyone,
:Bultaco: :Bultaco: :Bultaco:

OK I've had a good think about this bike and while it initially looked like it has some components that look mismatched, it might not.
I've been caught out before by the way made development improvements in their bikes and incorporated the improvements before they changed the model number to the next number. Most likely caused by poor inventory control, where they ran out of something before the production run for that bike was finished or equally likely when they had too many of something for the production run, they carried it over to the next model number.

In the case of the in Greg's photo which I'm going to say is nominally a model 99 because he told me so, the "odd" bits visible could be explained by it falling into the transition period in production from making model 85/99 Alpinas to making 115/116 Alpinas.
The frame and tank/seat is typical 85/99.
The front wheel, having no shoulder on the rim and having the conical hub, lines up with model 115/116 and all later Alpinas.
The rear wheel could be late 85/99 or early 115/116. Not later than that though because of the shouldered rim which ran out during model 115/116.
The fork tubes are what normally came on model 115/116 and later Alpinas (the tops ends are clamped with bolts rather than a taper fit in the top triple clamp)
The lower triple clamp is model 85/99 Alpina (and model 10, 27, 49, 80 Sherpa T)
The upper triple clamp is model 124/125 Sherpa T. There would have been a necessity to use a Sherpa T top triple clamp in conjunction with that steel lower triple clamp because the geometry of that steel bottom clamp is Sherpa T. Looks like they either ran out of top triple clamps with a taper fit for the tubes, or ran out of tapered top fork tubes. After the model 85/99, Alpinas moved away from Sherpa T steering geometry by fitting the same triple clamps as Pursangs and Frontera, with more trail and bolt-on handlebar mounts.
So my theory is that it is a model 99 from near the end of model 99 production.