jofritz Posted July 8, 2022 Report Share Posted July 8, 2022 Hi there, my name is Joachim, 52 Y and from Germany. Trials was a dream when I was a kid, now it is still a dream as I am a beginner in any way. Sometimes I just can't resist buying a bike, thinking it will run eventually. Newest one is a bultaco about 1970, first bike my age 😉 After spending some time on it I realise I am pretty clueless as there is not so much information easy to find as it is a Lobito 175 MK3 (think so!) Cleand the AMAL, polished some of the alloy, looks great, just like new, but no spark! I don't even now if I can easyly take of the flywheel and put it back on again without messing the whole timming up by moving it a bit... I think there should be some kind of nosre or nipple to make sure it will keep the timing... but I simply don't know... Well, probably someone knows a bit more than I know... would be great to get some hints... Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 9, 2022 Report Share Posted July 9, 2022 8 hours ago, jofritz said: Hi there, my name is Joachim, 52 Y and from Germany. Trials was a dream when I was a kid, now it is still a dream as I am a beginner in any way. Sometimes I just can't resist buying a bike, thinking it will run eventually. Newest one is a bultaco about 1970, first bike my age 😉 After spending some time on it I realise I am pretty clueless as there is not so much information easy to find as it is a Lobito 175 MK3 (think so!) Cleand the AMAL, polished some of the alloy, looks great, just like new, but no spark! I don't even now if I can easyly take of the flywheel and put it back on again without messing the whole timming up by moving it a bit... I think there should be some kind of nosre or nipple to make sure it will keep the timing... but I simply don't know... Well, probably someone knows a bit more than I know... would be great to get some hints... There are a couple of workshop manuals written in English for 5 speed Bultacos that are useful. One manual is in the Haynes series and it's pretty good. I just looked and there is at least one advertised second hand on eBay. Search for "Haynes Bultaco Manual". If you have a Mk3 Lobito it is a 5 speed motor and the Haynes manual will cover it. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 9, 2022 Report Share Posted July 9, 2022 (edited) The other brand manual is Clymer Edited July 9, 2022 by feetupfun Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted July 9, 2022 Report Share Posted July 9, 2022 Amal´s often have a worn throttle valve/ carb body. This shows up by problems getting a stable idling. Don´t fall into the trap of putting jets and nozzles that looks to be correct, but they may not be. I only put jets, nozzles and needles from parts in original wrappings sold by a reputable dealer, and correct sizes accordingly to original manuals or accordingly to Amalcarb.co.uk. During the years I have seen a number of incorrect combinations that don´t work well, and people have a tendency to blame Amal for everything inc bad weather.☹️ Quote Link to comment Share on other sites More sharing options...
jofritz Posted July 9, 2022 Author Report Share Posted July 9, 2022 The AMAL Carb looks just fine... one thing though... is it normal to have a brass mesh around the main jet, on float bowl side as second filter after the banjo filter... never seen it, not even on amal carb exploded views Quote Link to comment Share on other sites More sharing options...
feetupfun Posted July 9, 2022 Report Share Posted July 9, 2022 1 hour ago, jofritz said: The AMAL Carb looks just fine... one thing though... is it normal to have a brass mesh around the main jet, on float bowl side as second filter after the banjo filter... never seen it, not even on amal carb exploded views I've seen that on many Mk1 concentric AMALs Quote Link to comment Share on other sites More sharing options...
jofritz Posted July 9, 2022 Author Report Share Posted July 9, 2022 7 minutes ago, feetupfun said: I've seen that on many Mk1 concentric AMALs but having a clean tank and the banjo filter I could take it off, couldn't I? Quote Link to comment Share on other sites More sharing options...
pschrauber Posted July 9, 2022 Report Share Posted July 9, 2022 There is even too a German Bultaco workshop book from Switzerland available, (ZUG Verlag), see here:https://www.buecher.de/shop/buecher/bultaco-wettbewerbsmodelle-alpinafronterapursangsherpa-t/broschiertes-buch/products_products/detail/prod_id/39918726/ To the AMAL carb Carl Ekblom is pretty right about the jets and nozzles. IF you think you have a carb problem you might replace the jets against new one, too the needle and in case of AMAL please look up the status of the slide and the inner cylinder inside the carb body. AMAL had sadly a soft carb body and a soft slide too, this resulted in quick wear and likewise worn out slides and inner bore (cylinder). I personal like the AMAL not and have replaced them against something contemporary else. 1 Quote Link to comment Share on other sites More sharing options...
jofritz Posted July 9, 2022 Author Report Share Posted July 9, 2022 I have seen the book... but it covers Alpina/Frontera/Pursang/Sherpa T... does it cover my Lobito too? 1 Quote Link to comment Share on other sites More sharing options...
bullylover Posted July 10, 2022 Report Share Posted July 10, 2022 Yes it does jofritz. Use the timing information for the Alpinas for your Lobito. You will need a Femsa flywheel puller. Points gap is .40 mm and the timing will be around 2.9 mm BTDC. I can`t remember what the timing is for a 175 Lobito. That will work though. Quote Link to comment Share on other sites More sharing options...
carl ekblom Posted July 10, 2022 Report Share Posted July 10, 2022 22 hours ago, jofritz said: but having a clean tank and the banjo filter I could take it off, couldn't I? Yes, as far as I know you can. Haven´t seen those at Concentric Mk1, but at Mk2. Might function as a small restriction at full throttle but I am unsure. If they do you may test a slightly smaller main jet, or they may increase fuel flow at full throttle. I would thoroughly clean everything and keep it as it was to avoid uncertainties. Be aware, the Amals function well but have a very limited lifespan. This is why we now have the Concentric Premier carb, with anodized throttle valves an some added extras. A few of them even have alloy bodies Quote Link to comment Share on other sites More sharing options...
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