motosinge83 Posted February 21, 2007 Report Share Posted February 21, 2007 (edited) Motosinge83 Edited December 29, 2007 by Motosinge83 Quote Link to comment Share on other sites More sharing options...
martinm Posted February 22, 2007 Report Share Posted February 22, 2007 (edited) Whats this Armstrong doing on our nice new SWM forum ? Shame on you Motosinge There seem to be a few of these Armstrong Jumbo's coming out of the woodwork at the moment, they use an Amal carb....and by the look of it, a petrol tap from Stevensons Rocket. The works Jumbos, like Stu's Bernie bike, have a section welded into the front pipe to extend it, maybe to soften down the power. Here's an example, wonder whats happened to the shocks ? Martin Edited February 22, 2007 by MartinM Quote Link to comment Share on other sites More sharing options...
malcra Posted February 26, 2007 Report Share Posted February 26, 2007 hmm, see that the Jumbo prototype has a steel swingarm, rather than the alloy box-section one. Mine has a steel swingarm, but understand that this and 35mm, rather than 38mm, forks were specific bikes that might have ended up in the US ? Engine number places the bike around July 83 manufacture. Quote Link to comment Share on other sites More sharing options...
baldilocks Posted February 28, 2007 Report Share Posted February 28, 2007 The first photo posted is what I recognise as a 350 Jumbo SWM as ridden by Schrieber, Michaud et al in the 83 world championship. They had the clutch lightener under the tank fastened to the cylinder head. Some good club lads got them for the ssdt in 83 but they were very powerful bikes. Quinns supported rider that year on SWM was a guy called Geoff Mcdonnell, a good rider in our centre ( he has a few scott spoons so he wasnt just average). He found the jumbo way to powerfull and claimed you could ride most sections in the SSDT in 3rd or 4th gear IF you could keep up with it ! the Jumbos had a reed valve engine rather than disc valve I think. Ive seen a couple of other posts referring to smaller CC jumbos but I thought the 350 was the only one actually called a jumbo ? Quote Link to comment Share on other sites More sharing options...
whatgearyouusing Posted March 1, 2007 Report Share Posted March 1, 2007 Ive heard a lot of people say how powerful the 350 jumbo is.Is that "powerful" as compared to other bikes of that era?As I havent had the priviledge of riding a Jumbo how do they compare with the power of say a modern bike? Quote Link to comment Share on other sites More sharing options...
malcra Posted March 1, 2007 Report Share Posted March 1, 2007 First trial on my Jumbo on Sunday, and i've been riding a 280cc 320TL for a year. My engine has been rebuilt, but may not be perfect and I've got to check the situation with the reed valves and to play with the ignition timing: + its got plenty of power and more short burst blast than the 280, but the 280 is pretty impressive as has been said on the SWM forums, the 280cc engine is more "rideable". Its got more grunt for sure and on Sunday in the mud it could earn its place in the front row of the Italian pack no problem. + the main thing about the Jumbo is the frame and riding position. Although I've not got the alloy section swingarm (yes please if anyone has one), the frame geometry is much like a more modern bike and comparing that with a 78 Guanaco, its more like 15 years than just 5 in terms of bike design. It makes the Jumbo much easier to ride. + the cluch lightener is good, but i have a (surpringsly) light clutch on my 320TL so its one finger on both bikes. I'm conitnuing to mod and tune the Jumbo and "plan" to rider 10-15 trials this year on it. Quote Link to comment Share on other sites More sharing options...
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