Originally Posted by zenduddhist
2009 Sherpa: I too have a hard time with cold start. Already added the 130 main jet and 20 pilot jet. What I found is that if I loosen the screw that allows the float bowl to drain, and leave it open until I get a nice flow coming for about 5 seconds, then shut the drain screw, it will start easier. Sometimes, that is on the only way to get it to start. Sounds like I am not getting enough fuel after it sits awhile? Maybe too much?
Also, probably related, I took the fuel tank off the bike and I can't get the fuel to completely stop coming out of the bottom of the petcock. I have tried it in both the "on" position and the "reserve" position. Obviously, when I put it in "prime" position, I get a lot of gas coming out, but when I switch to "on" or "reserve" it still drips.
For the cold start, it sounds like you just need to get some fresh gasoline into the float bowl. I got into the habit of putting the petcock into prime, and leaning the bike over until the gas came out of the overflow hose from the carb. I do that on my "newer" dirt bikes too, to prime them before starting.
As for the petcock, sounds like a leaky o-ring. Would be a good opportunity to do the Yamaha petcock conversion and lose the vacuum diaphragm/hose.