andyz Posted September 19, 2009 Report Share Posted September 19, 2009 Hi All, I've just purchased a 1979 Cota 349 as a first foray into the world of classic trials, after years of motocross and enduros. The bike had been laid up for a few years and the owner claimed that it had been completely rebuilt (whatever that means) previous to this. After putting new oils in the primary and gearbox and fresh fuel in the tank, it fired up, second kick, but it seems very rattly! So rattly in fact that its a bit emabarassing riding it in my back garden! The noise seems to be mostly from the top end, possibly piston slap and small end, but its hard to tell. Should this engine be mechanically quiet, or is a bit of rattle normal? If its not normal then could anyone suggest the most common source of rattling on this type of engine. The other area of concern is the lack of any protection of the swinging arm from the top run of the chain. I believe that the rubber tubes which were fitted to these bikes originally are not easy to find, so how does everyone else stop the chain wearing through the swinging arm? With those minor items sorted, I'll then be looking for any classic trials going on in Kent, UK and surrounding areas - suggestions very welcome! Many thanks, Andrew Quote Link to comment Share on other sites More sharing options...
toofasttim Posted September 19, 2009 Report Share Posted September 19, 2009 To be pedantic the 349 was introduced in '80. Chain tubes: AFAIK some mob in Spain still supply. Others will be more forthcoming with details. If it's piston slap, don't fret. The Monts rattled something horrible (so did the sherpas). Quote Link to comment Share on other sites More sharing options...
feetupfun Posted September 20, 2009 Report Share Posted September 20, 2009 Yes probably piston slap but may also be the primary drive gears if the crank end is running out. If the noise is from the primary gears the noise will be the same under most conditions while piston slap will sound worst while on closed throttle overrun from highish RPM. Spring loaded tensioners seem to be more popular than the chain guides. Theres a neat one available that mounts on the gearbox case. Have a look at what other riders use. Museum standard bikes will have the tube guides while many ride bikes have a tensioner. Quote Link to comment Share on other sites More sharing options...
toofasttim Posted September 20, 2009 Report Share Posted September 20, 2009 Dave, that chain tensioner came std with the later 349's it was only the first model (this one) that didn't have it. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted September 20, 2009 Report Share Posted September 20, 2009 Its good they eventually ditched the tubes. Thanks Tim I wasn't sure which models had them. Quote Link to comment Share on other sites More sharing options...
toofasttim Posted September 20, 2009 Report Share Posted September 20, 2009 I thought the tubes were a good idea. They weren't as vulnerable as you'd think and they kept a lot of crud off the chain BUT they did accumulate crud inside them and cleaning that out was a nightmare. Quote Link to comment Share on other sites More sharing options...
steve Posted September 20, 2009 Report Share Posted September 20, 2009 Hi All,The other area of concern is the lack of any protection of the swinging arm from the top run of the chain. I believe that the rubber tubes which were fitted to these bikes originally are not easy to find, so how does everyone else stop the chain wearing through the swinging arm? I recently bought a 349 chain tensioner from Sandifords through Ebay. It came complete with the swinging arm protector. It was dirt cheap aswell! Give them a call - if they've run out send me an email and I'll give you mine. It doesn't fit my Cota 330. Steve Quote Link to comment Share on other sites More sharing options...
andyz Posted September 20, 2009 Author Report Share Posted September 20, 2009 Many thanks for your replies! This looks like a great forum! Cheers, Andrew Quote Link to comment Share on other sites More sharing options...
vintagecota Posted September 22, 2009 Report Share Posted September 22, 2009 349s DID start from '79. '79s and '80s had red tanks but different stripe kits. Quote Link to comment Share on other sites More sharing options...
thedktor Posted September 23, 2009 Report Share Posted September 23, 2009 Interestingly my 349 was completely rattle free before I stripped it down to find the whole engine badly corroded! To be fair the piston looks unworn, but the point to make is that a 349 in "normal" condition should not really rattle should it? Unfortunately taking the barrel off is not as easy as some bikes due to recessed bolts... but there is a post of my experiences (and advice) if you decide to open her up. Steve Quote Link to comment Share on other sites More sharing options...
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