Yamaha RX10H Service Manual

Also see for RX10H: Owner's manual

Contents

2-57CARBURETOR TUNING INSPADJMain jet selection chartSpark plug color Diagnosis RemedyLight tan or gray Carburetors are tunedproperly.Dry black or fluffydepositsMixture is too rich. Replace the main jet with the next smallersize.White or light gray Mixture is too lean. Replace the main jet with the next largersize.White or grayinsulator with smallblack or grayishbrown spots andelectrodes having abluish-burntappearanceMixture is too lean.The piston is damaged orseized.Replace the piston and spark plug.Tune the carburetors again. Begin with low-speed tuning.Melted electrodesand possibly ablistered insulatorMetallic deposits oninsulatorMixture is too lean.The spark plug melted.Check the piston for holes or seizure.Check the cooling system, gasoline octanerating and ignition timing. After replacingthe spark plug with a colder type, tune thecarburetors again. Begin with low-speedtuning.TroubleshootingTrouble Diagnosis AdjustmentHard starting Insufficient fuel Add gasoline.Excessive use of thestarter or chokeReturn the starter lever to its seated posi-tion so that the starter valve is fully closed.Fuel passage is clogged orfrozen Check and, if necessary, clean the fueltank air vent, the fuel filter and all of thefuel passages. Check and, if necessary, clean thecarburetor air vents, fuel passages and thefloat valve. Clean the float chamber of any ice or water.Overflow Adjust the fuel level.Poor idling: Poor performanceImproper idling speedadjustmentAdjust the engine idle speed.Refer to “Low speed tuning”.at low speedsP l ti Damaged pilot screw Replace the pilot screw. Poor acceleration Slow response to Clogged bypass hole Clean the bypass hole. Slow res onse tothrottle Engine tends tostallClogged or loose pilot jet Remove the pilot jet, clean it withcompressed air and then install it. Make sure that the pilot jet is fully tightened.stallAir leaking into thecarburetor jointRetighten the clamp screws on thecarburetor joints.Defective starter valve seat Clean or replace the starter valve seat.Overflow Adjust the fuel level.