Basket Cases

[Greg Harding]

Hi Everyone,

Well as David has so cleverly put it, looks like OSSA is more than just a pOSSAbility for next years theme!

Billy, if we keep on alternating the theme between Japanese and Spanish, Montesa will have it's turn in 2016. But much more importantly, ride what you want, just don't miss out on the fun.

Mark K, Oh boy, you forgot that OSSA made Orange Ones as well !

David, the factory dints in that Alpina frame give it away that it is very light wall tube. If the tubes were thicker, there would be a bigger radius on the edge of the impression. Is this the new Vinduro weapon, or do you have other plans, maybe fit a Trials Gonelli ?

Yammyty, top job on the BSA tank! Was the Bantam the only BSA model to use Poultry in it's name and graphics?

Chippy, I have been looking at the pair of MAR wheels in my shed and wondering how many parts were missing that hold them together or is that apart?
Thankyou for the offer of your OSSA 250 MAR , something is not quite right as it is in just one piece!

Another thing I am not too sure about is what is going on with all this GREEN, is it just that GREEN and MACHINE go so well together?

GREEN Japanese, then GREEN Italian and now GREEN OSSA!

Here is a photo of Steve's ITALJET Piuma frame 6.990 kg and swingarm 2.960 kg

IMGP7705.JPG (165.67 KiB) Viewed 6650 times

[Bully fanatic]

Hi David. I reckon you should go with the Pursang front mudguard as it looks more natural on the 138. That shape looks like a MK 6 shape I think. The MK 7 and 8 had a deeper shape and sides on them. Preston Petty guards also look fine on these as well and were a usual modification on any old bike. They are back in production these days too. Graham.

[David Lahey]

Hi David. I reckon you should go with the Pursang front mudguard as it looks more natural on the 138. That shape looks like a MK 6 shape I think. The MK 7 and 8 had a deeper shape and sides on them. Preston Petty guards also look fine on these as well and were a usual modification on any old bike. They are back in production these days too. Graham.

Graham - thanks, I hadn't thought of using a Preston Petty. Yes they do look pretty normal on old trail bikes, especially the PP rears that had an integrated tail-light.

Greg - with a frame that light, it is no wonder it was called a Piuma, which come to think of it, is pretty close to being named after poultry (like a Bantam)

The challenge is on now to find a full-sized twinshock era trials frame lighter than the Italjet Piuma

Ah yes the M138 Alpina. That model Alpina is as far removed from the trials-bike-like early Alpina design as any of the mountain-country trail bikes of the era could be. It has a 350cc capacity motor with much less flywheel mass than a 325 Sherpa T, Pursang/Frontera triple clamps and a longer wheelbase than the Bultaco trials bikes. Mine is now 360cc and is quite "refreshing" to ride. Yes the current plan is to use it for Vinduro riding, and the local mountainous trail rides. My original plan in the early 1990s was to have an Alpina like the one I rode as a kid, not suspecting that this one is quite different to the very trials-like 1973 325 Alpina I had as a kid. This one was a basket case that came to me as part-trade for my Suzuki TM125 in about 1998. It feels pretty terrible to ride in trials sections. Maybe with trials tyres it would be easier but I think the steering geometry is quite unsuitable and the motor is too snappy. I think the Alpina you rode at Conondale a few years ago might have had the same steering geometry

[Mark K]

...... Mark K, Oh boy, you forgot that OSSA made Orange Ones as well ! ......

I believe that as well as green white and grey, they also came in orange, in yellow, and red, and if memory serves me correctly, a whole range of colours for the road racing models, which is why I said back in November:

..... I'd suggest GREEN SPANISH but OSSAs that weren't MARs came in other colours too, so instead I'll practice my alliteration.... ......

The MARs are still the prettiest though.

[billy]

....... Billy, if we keep on alternating the theme between Japanese and Spanish, Montesa will have it's turn in 2016. But much more importantly, ride what you want, just don't miss out on the fun. ..........

All good.

Don't want the colours running. A MONOSSA doesn't bear thinking about.

[Mark K]

Hey Billy, just in case there is any doubt I just want to let you, and anyone else know, that these themes started off a few years back when a couple of mates decided to co-ordinate which bikes they rode. The themes have nothing to do with the official running of the event. Anyone is perfectly welcome to turn up with whatever bike they want, even those weird and wonderful modern things.

That being said, I personally like the idea, it adds a level of interest, and hopefully involvement maybe getting some bikes out which wouldn't otherwise be there.

[chippy]

Hello everyone,
Mark K you are exactly right with the theme for Conondale. It is good to see such a variety of makes at Conondale each year, the theme is just adding some additional interest and getting a few more twin shocks out of the shed and with Greg and I, getting some bikes completed for the event, even if it is the eleventh hour!!!

Greg, I said you could borrow my Mar 250 that is running, but I didn't necessarily say that it was in one piece....but I'm sure you will be able to sort it out.

Billy, my phone cut out the other day due to poor reception and I will ring you back soon.

Greg, I will get some spokes for those Ossa wheels too. As you know, I have a bit of time up my sleeve at the moment, so I can get started on my Ossa Mar 350 restoration. I will post some photos shortly.

David Lahey, just out of curiosity, what twin shock bike would have the heaviest flywheel. I know that the Ossa Mark is all lead and very heavy.

Chippy

[David Lahey]

David Lahey, just out of curiosity, what twin shock bike would have the heaviest flywheel. I know that the Ossa Mark is all lead and very heavy.Chippy

Yes the 250 MAR magneto flywheel is pretty heavy, but remember it has no flywheel on the drive end of the crankshaft. 325 Bultaco Sherpa Ts have a heavy magneto wheel and a heavy wheel on the drive end too. Cota 348 also has external flywheels both ends. The bigger the motor capacity, the bigger the flywheel effect required
The 250 Japanese 2 stroke trials motors have heavier crank wheels than the 250cc and 300+cc Spanish bikes so can get by with smaller external flywheels than what is needed on the Spanish motors.
Back to your question, the strongest flywheel effect I have ever felt when riding a twinshock is a special Yamaha 360cc trials motor built for Peter Paice in 1977 using a design based on the TY250 motor and developed by the works Yamaha people in Europe at the time. As you might expect that motor was very strong, and needed lots of flywheel inertia to make it rideable.
Maybe for a bit of a laugh we could have a weigh-in for flywheels and crankshafts that people can add to when they have their motors apart?

[chippy]

Hello everyone,
David very interesting and I remember watching Peter Paice when I competed a lot in NSW in the late 70's and watching him ride was really inspiring and some of his bikes did seem 'trick' in the day.

Also I have just weighed the Ossa Mar 350 magneto flywheel and it is 4.7kg. Also weighed the 350 crackshaft and it is 3.3kg as against the Ossa Mar 250 is 2.5kg.

I was especially interested in the weight of the magneto flywheel as I'll let you know why later....

Chippy

[chippy]

Hello everyone,
Here is a photo of my Ossa Mar 350 basket case. This is practically how I got it. THe frame has been sandblasted and powder coated, but as you can see the powder coaters only have a grey colour. Frame is about to be rubbed now for a coat of paint.

Ossa 350.jpg (31.48 KiB) Viewed 6582 times