charliechitlins Posted November 29, 2004 Report Share Posted November 29, 2004 If anybody has one, I sure would appreciate it if you sent me some detailed photos of your bike so I can put mine back together properly. Thanks! c Quote Link to comment Share on other sites More sharing options...
feetupfun Posted November 29, 2004 Report Share Posted November 29, 2004 If anybody has one, I sure would appreciate it if you sent me some detailed photos of your bike so I can put mine back together properly.Thanks! c You will find lots of useful info on Jared Bates' site below and a good RHS photo of a 1972 Cota 247 in his photo gallery. http://www.southwestmontesa.com/ There are also many other sites with Cota photos. Have you seen www.todotrial.com It has good info and a good set of links to sites with plenty of photos of perfectly restored Spanish trials bikes. I'm glad you got a pre '76 Cota 247. They certainly are a fantastic looking bike. Quote Link to comment Share on other sites More sharing options...
dabmeister Posted December 1, 2004 Report Share Posted December 1, 2004 Check out these galleries, all sorts in there http://www.ataq.qc.ca/galerie/index.php?folder=/Mus%E9e/ Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted December 5, 2004 Author Report Share Posted December 5, 2004 Thanks fellas, mates, guys and y'all. What I would really like, also, are some detailed photos of an original or properly restored bike, so I know just how everything goes together. I would be willing to pay. This one I have has been pretty well...um....personalized over the years, and I would like to know how it's really supposed to look. Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted December 5, 2004 Author Report Share Posted December 5, 2004 Yikes! What a beautiful job. Is it your's? It's a real temptation to restore mine (I wouldn't be afraid to ride it!), but I have a big restoration in front of it. I think I've seen my next project, though. Is that one earlier than '74. or could a '74 be had with a silver frame? Anybody know where to get a toolbox? Thanks so much for the pics! Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted December 5, 2004 Author Report Share Posted December 5, 2004 Oh, yeah...excuse my ignorance, but I've never used a compression release for anything other than starting. How would one use it while riding? Quote Link to comment Share on other sites More sharing options...
woody Posted December 5, 2004 Report Share Posted December 5, 2004 (edited) It provides very effective engine braking when the engine is running. It will stall the engine on anything up to say three quarters throttle. Over that the engine will carry on running. Consequently, as long as the clutch lever is not pulled in.... and the ground offers enough traction it becomes a very effective rear brake on downhills. By slowing the engine down it also slows the back wheel, giving the braking effect. Once you get the feel for this you can use it as a brake without stalling the engine, juggling it on and off during a decent. It works pretty well. Of course, if the ground is too sippery to offer much traction, the decompressor will just stall the engine, as it would if the bike were in neutral, as the rear wheel has nothing to drive against to keep the engine turning. When I used to use my Ossa MAR on the road regularly back in the 70s, hooning around with my mates on their road bikes, not to mention the odd trip to school, in the absence of efective brakes the decompressor made a very good substitute. Makes a hell of a noise too if pulled in at speed. For those familiar with Monty Python, it must sound like Mr Creosote farting. Pedestrians would leap out of their skins when the decompressor was pulled at 50 - 60mph for some hard braking. Bus queues were always a good source of amusement too. If you brake using the clutch/brake method, the 'deek' is no use to you but if you use the engine it can be a very useful tool indeed. Also audibly warns other riders inspecting the section to get out of the way - Ossa with no brakes approaching rapidly... Oh yes - I almost forgot. That really is a cracking Monty. Beautiful looking bike - almost as nice as a MAR Edited December 5, 2004 by Woody Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted December 5, 2004 Author Report Share Posted December 5, 2004 It provides very effective engine braking when the engine is running. It will stall the engine on anything up to say three quarters throttle. Over that the engine will carry on running.Consequently, as long as the clutch lever is not pulled in.... and the ground offers enough traction it becomes a very effective rear brake on downhills. By slowing the engine down it also slows the back wheel, giving the braking effect. Once you get the feel for this you can use it as a brake without stalling the engine, juggling it on and off during a decent. It works pretty well. Of course, if the ground is too sippery to offer much traction, the decompressor will just stall the engine, as it would if the bike were in neutral, as the rear wheel has nothing to drive against to keep the engine turning. When I used to use my Ossa MAR on the road regularly back in the 70s, hooning around with my mates on their road bikes, not to mention the odd trip to school, in the absence of efective brakes the decompressor made a very good substitute. Makes a hell of a noise too if pulled in at speed. For those familiar with Monty Python, it must sound like Mr Creosote farting. Pedestrians would leap out of their skins when the decompressor was pulled at 50 - 60mph for some hard braking. Bus queues were always a good source of amusement too. If you brake using the clutch/brake method, the 'deek' is no use to you but if you use the engine it can be a very useful tool indeed. Also audibly warns other riders inspecting the section to get out of the way - Ossa with no brakes approaching rapidly... Oh yes - I almost forgot. That really is a cracking Monty. Beautiful looking bike - almost as nice as a MAR OK...I'm not doubting you...but I think I'm a little dense. Wouldn't compression give more resistance to the rear wheel? When I want to spin an engine on the lift (to check timing, for instance), I jack up the back wheel, put it in gear, take out the sparkplug (eliminating compression) and turn the back wheel. Quote Link to comment Share on other sites More sharing options...
woody Posted December 5, 2004 Report Share Posted December 5, 2004 (edited) Sorry Charlie - I can't help you out with the science of it. It baffles me too and I have no idea how it works the way it does. By all reaonable thinking, releasing the compression should make it go quicker you would have thought. If I pulled in the valve lifter on my 426 Yam whilst rolling down a hill in gear, throttle off, I am pretty sure it would accelerate. I not going to try it though as valves are expensive..... PS - it is a must have accessory for the discerning Spanish 70s classic owner. Period fitment..... or at least in the UK it was. It was definitely the only way to stop the buggers Edited December 5, 2004 by Woody Quote Link to comment Share on other sites More sharing options...
vintagecota Posted December 6, 2004 Report Share Posted December 6, 2004 The bike in the pictures could be a '74 as the black frame began from Feb.'74. No fork boots, eh? Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted December 6, 2004 Author Report Share Posted December 6, 2004 Right! No boots. I'm scheming a way to graft the "Montesa" part of my torn up ones on to my generic aftermarket ones. Got to spent a whole hour on it today between chores. Forks completely empty, springs crusty and 2 different lengths, tubes bent. Time to call Forking by Frank. But, hey...ya can't put a price on a good time. The good news: too-long primary drain plug was interfering with shift mechanism. Presto grind-o...shifts great. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted December 6, 2004 Report Share Posted December 6, 2004 The two stroke decompressor as on that Cota 247 works by opening only a small hole between the combustion chamber and the outside air. The small hole allows air to flow in and out in a controlled manner dissipating energy just like fork oil moving through the orifices in the damper rods also creates a drag which dissipates energy. A big hole in the head (as in taking the spark plug out) doesn't restrict the flow as much so doesn't provide as much braking effect. On a 4 stroke, the decompressor is there to allow the motor to turn over easier for starting so it works by opening a large hole between the combustion chamber and the exhaust header. In the case of a 4 stroke, an exhaust valve is held open continuously to provide the big hole. Please be aware that in dusty conditions, with the type of decompressor shown on that Cota 247 it is possible for dust to enter the combustion chamber via the decompressor hole (unless it has a filter), increasing ring, bore and piston wear rates. Quote Link to comment Share on other sites More sharing options...
brian r Posted December 7, 2004 Report Share Posted December 7, 2004 The beautiful bike in the picture shifts on the left. Wouldn't that make it at least a '74? Quote Link to comment Share on other sites More sharing options...
vintagecota Posted December 8, 2004 Report Share Posted December 8, 2004 Left-side shift was from Dec. '72. Quote Link to comment Share on other sites More sharing options...
dgshannon Posted December 8, 2004 Report Share Posted December 8, 2004 Left-side shift was from Dec. '72. Don't think so. The left side shift on Cota 247's first appeared on the 1974 models, to the best of my knowledge. The change from a silver to black frame color came mid year on the 1974 models for sure, which they marketed as the "Still Better". I have a 1974 "Still Better" (manufactured around April 1973) along with a full page color marketing ad featuring the bike. You will occasionally see the ads come up for sale on E-Bay. Quote Link to comment Share on other sites More sharing options...
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