Peter Cobbold Posted November 9, 2015 Report Share Posted November 9, 2015 (edited) Lets hope it is the butterflies. But its worth bearing in mind that the carbs might be working fine. In which case the different piston lifts are revealing different air flows and we start looking into rockers, valves, cam lobes etc. So I'd do compression measurements next, if the buttlerfles are sync'd. Peter Edited November 9, 2015 by Peter Cobbold Quote Link to post Share on other sites
RogerH Posted November 9, 2015 Report Share Posted November 9, 2015 ..or carb manifold gasket leak.... possibly/maybe/could be/ probably not though!! Roger Quote Link to post Share on other sites
BlueTR3A-5EKT Posted November 9, 2015 Report Share Posted November 9, 2015 Swap dashpot, piston. spring, needle assy from front carb with back carb. Just ubdo 3 screws on each and lift the assemblies out - DO NOT mix up the pistons and dash pots as they are supposedly matched. There is a timing test for them. Does the problem move with the dash pot assemblies? You should not need to mess with the mixture as this is only an in the garage test. Cheers Peter W Quote Link to post Share on other sites
Lebro Posted November 9, 2015 Report Share Posted November 9, 2015 Link below may be of use http://sucarb.co.uk/technical-hs-type-carburetter-tuning-multi Bob. Quote Link to post Share on other sites
mjdearing Posted November 9, 2015 Report Share Posted November 9, 2015 worth checking float bowl overflows i had a blocked overflow (rust in small steel pipe) on one carb it did crazy things which included out of balance piston lifts ? Quote Link to post Share on other sites
Peter Cobbold Posted November 9, 2015 Report Share Posted November 9, 2015 worth checking float bowl overflows i had a blocked overflow (rust in small steel pipe) on one carb it did crazy things which included out of balance piston lifts ? How'd it do that ? I could see the air pressure above the fuel in the f/c going screwy, perhaps dropping below atmospheric. That would lean the mixture badly. Or fuel vapour adding pressure and richening the mixture. But leaning or richening the needle would not need to change position. I dont see the link to the piston lift.... Peter Quote Link to post Share on other sites
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