Peter Campbell Posted February 3, 2012 Share Posted February 3, 2012 Newbie here. Just bought a 78 DT400 sight unseen on CL. PO said it ran fine. When I ride it it runs good for about a mile then starts pinging and knocking and becomes unrideable. I've cleaned the carb three times and have ensured that the bike is stock (80 pilot jet, 180 main jet, main nozzle I am not sure of did not see any markings) I have two questions: First is are the main nozzles marked? Second is can the air jet be seen from the rear of the carb? I can't see one on mine and I'm wondering if it got shot out during the many carb cleanings it had. Do they even have an air jet? Any help would be appreciated thanks... Link to comment Share on other sites More sharing options...
blackhat250 Posted February 4, 2012 Share Posted February 4, 2012 Welcome peter. " that pinging & knocking is Detonation , this will result in a holed piston . timing , or fuel [ high octane] is usualy the problem,, or carbon on top of piston, glows and pre-ignites before piston is at top of stroke, as you can imagine ,if bang is early, its hell on piston, , Start with decoke, then check fywheel marks,, as Dt 400 is CDI. it still needs to be timed.. a dial gauge is needed, set to degree ,Before TDC , thats wen pointer lines up with pulser coil , oh spark plug shoulf be B9ES ,,,, Link to comment Share on other sites More sharing options...
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