jimsbeast2720 Posted November 15, 2011 Report Share Posted November 15, 2011 hello, this is my first post on here, i have always wanted an old trials bike and a few months ago i found a montesa 348 really tidy model i bought it cheap because it was advertised as having no spark, im npo bike expert but i am a mechanic so i know a few things, i straight away bought myself new points, condenser and spark plug, firstly i changed the plu and it ran perfectly! i was shocked but it ran fine for about half an hour, i then took it out for about the same time a couple of times in 2 weeks, then she decided to give up, i checked it over and it had np sperk at the tip but the plug would always spark on the side of the plug against the block like if it was weak, i decided to change the points and condenser and made a tidy job, well i thought so! but the problem was exactly the same no change, so i bought a new coil, which i put on today and it stopped sparking altogether now i have nothing at all! some issues which might be involved, the coil is slightly different, it was advertised to fit my bike but its not made by motoplat like the old one and it wont fit just where the old one did i will have to adapt it to fit, its a different shape basically also: i used a thick solder wire on the conderser cos thats all i had and it took a while, this caused the condenser to warm up quite a bit, and im worried i might have damaged it what do you guyus think? any advice very much apprechiated as im really stuck thanks james Quote Link to comment Share on other sites More sharing options...
bullylover Posted November 16, 2011 Report Share Posted November 16, 2011 (edited) Hello jimsbeast2720. I don`t know to much about Montesa`s but what was the points gap after you changed the points. I think it should be 14 to 16 thou or .35 to .45 mm. With the condensers excess heat can damage them. The best bet with condensers is to use a car one of a similar size instead of the motoplat one as they are easy to get hold of and it helps to put them up under the fuel tank out of the heat. Remove the old one and splice into the wire going to the coil and join it up. Don`t forget to earth the condenser to the frame. I think the plug gap is important on the montesa`s as well. I am not sure what it should be but the Bultaco`s are 40 thou which might seem to be very close but that is what they like. They are Spanish after all. The timing is also very important as well and I don`t know what it should be but some of the montesa experts on here should be able to tell you. A different coil shape should not matter either as long as the resistance and other electrical measures match. Good Luck. Bully Lover. Edited November 16, 2011 by bullylover Quote Link to comment Share on other sites More sharing options...
dadof2 Posted November 16, 2011 Report Share Posted November 16, 2011 I would check the output from your source coil. Spin the engine with an electric drill at about 600 to 800 RPM and you should get 23 or more AC volts. Cheers Quote Link to comment Share on other sites More sharing options...
heavywrecker Posted November 16, 2011 Report Share Posted November 16, 2011 Are you sure the replacement coil is AC not DC ? Fitting the condenser under the tank with the coil is a good idea. Go to the local car factors and get a Lucas DCB203C condenser, comes with a bracket and a wire, most convenient. I presume you are setting the points up with a TDC tool or dial gauge? Cheers Bill Quote Link to comment Share on other sites More sharing options...
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