yamaha dt 125 1984 problem?
i have a yamaha dt 125 1984, iv just done a top end rebuild on it and was all running fine , replaced all the gaskets ( base/ Head) but when i ride it, it judders LOADSSSS.
i had a make du gasket for about a month,,
This all happened when i rode it for about 4 mile full on !!! bout 90 -100 The whole time..... I ran outta petrol then the juddering started!
Now, i get to about 4 thousand rev fine, then judders n wont go over.. untill i let the throttle off and on a little then it will pick up 2 about 50 Just( Caining it) any help please , 
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Comments
youve pulled some crap into the carb...strip and clean it...oh and doing 90 on a freshly built engine is a no no...
Try keeping the throttle on it's just trying to get past the power band where the engine speed reached a point where no mixture is lost out of the exhaust port. It may need breaking in. Just keep throttle on full when you reach 4000 RPM. expect a rocket reation but it wont pull a wheely at that power so don't worry. If not it just the throttle cable not pulling on t ecrab in the way that it should do.
90-100mph?
You have an extremely optimistic Speedo!
Run bike flat out, then stop as quickly as possible and check Spark Plug colour.
If it's showing white to light Grey, then it's running weak.
Try a bigger Mainjet.
Also try bike without Air Filter.
WOW !!!! ONE HELL OF A 125 TO CRUISE AT 90 /100..MUST GET ANOTHER ONE OF THESE ..MUST HAVE BEEN SOMETHING WRONG WITH MINE..ANYWAY CHECK CARB AND CABLE ESPECIALLY CARB WHEN RUN OUT OF PETROL ..