Question about Yamaha RD 250 Motorcycles

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Hello, I have just replaced one of the carbs on my RD LC YPVS 350 as it was leaking from the overflow pipe. I have replaced the float and the bike is back running but now seems to be "holding back" on a run until I put the choke back on. It then runs ok for a while and then loses power again - any suggestions please?

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Floater is set wrong, it closes to quickley not enough fuel in the boll
I had same problem. First it was overflowing then I set floater diferently then it wasn't runing properly just like yours

Posted on Aug 20, 2010

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By putting the choke on you are effectively making the fuel mixure richer. If this makes the bike run better, it points to not enough fuel.
As this started when you fitted a new carb, I would start by checking the main jet size on the new one you fitted, it could be too small. You will need to take the carb off and undo the four little screws on the float bowl. Take this off and roughly in the centre will be the main jet. You should be able to unscrew this and you will see a number written on it. This is the jet size. If you have a workshop manual, check to see if it is the correct size. You could also swap it from the carb that leaked.
If this is ok, check the float height. Again, this will be covered in the manual.
Incidently, why not just cure the leaking problem from your original carb. Remove the float bowl, you will see the float secured by a pin. Remove the pin and the float lifts away. Under it you will see the float needle. Tip this out and check its condition. Also check the brass seat where it came from for tiny specs of muck.
Finally, if you removed both carbs make sure you didnt switch float bowls by mistake. They are different!
good luck!

Posted on Aug 02, 2010


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