Motorcycle Repair: 1974 yamaha dt100 enduro, yamaha dt 100, yamaha dt100

Question

dt   QUESTION: OK,any info would be great I bought an Yamaha dt 100 its a two stroke when I bought it I was toldit needed to be push started after sitting over night however after test riding it I brought it home and pit it in the garage a few days later I got on and it started first kick it ran great all day the next day I rose it up the street and it died I checked the plug it was fouled so I cleaned it up and it started again but quickly fouled the plug I tested compression its 150 after around 10 kicks I checked spark its good I tried starting fluid but I can't even get a pop out of the thing I would assume its Carb related but when it ran the idle and throttle were perfect so if you have any ideas please help thanks

ANSWER: James,you are close its still fuel related. The carb may not be set right and may need to be removed and gone through cleaned and adjusted. Also just a note these older bikes used a oil injector system that was set up for Yamalube injector oil. A lot of time an owner will substitute a cheaper oil that is easily obtained like from Walmart. It could be thinner and now the oil pump that mixes the fuel may go berserk and put in to much. After checking the carb check on the oil in the tank,some have done away with the tank and started premixing it. Then put a fresh spark plug and go one number lower,example" Bike has B8ES go to a B7ES,the lower the number the hotter the plug. Try to stick to a NGK plug. Do not use a Champion brand they dont work well.The compresion is good. Sometimes the crankshaft seals dry up and cause the cases to leak making it a lean running condition but this doesnt sound like it.

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QUESTION: OK,I had already bypassed the injector when it fouled the first few plugs the Carb was working fine when it was running ill check it and ill also use a hotter plug a few questions could the spark be weak ( I have an in line spark.     Checker on a 12volt car it lights up white on the 6 volt bike it was orange) I thought possibly the point gap is off but can't find a spec. For what it should be and also if the exhaust is gummed up what effect would that Have i mention the points/spark because even with starting fluid I wasn't getting any pop thanks for your time

Answer
James,This is a tough one . Try checking the intake system on the down side of the carb. The reeds can curl up on the edge and not seal or they may be damaged so that the carb wont draft the fuel efficiently. It could let your starting fluid blow back out and not have enough in the cylinder to fire or let some of the air out and only leave enough fuel to fire but foul the plug. Just check it out first before spending any more money.