Trying to tune up my HS4, damn flatspots. Working on the float level, where do I want the fuel to sit in the jet? At the moment I have the fuel puddling slightly above the main jet, before I had it sitting just below. Neither seems to fix the flat spot, but if I can make sure it isn't the float level then I can move on to the next possibility.

just below opening of the jet... where is the flat spot ? can you describe how it comes on...

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did I tell you that I won a trophy?

flat spot is between 2000-3000rpm. It isn't too bad driving normally, you can feel a slight loss of power. Really noticable when your giving it some, it takes off around 3000rpm, then when you change up you catch the tail end of the flat spot before it starts to rev again. Since it doesn't seem to be the float level I'm tempted to try different dashpot oil - running ATF at the moment but I'm thinking maybe some 20w oil and see what that does. Other than that I'm running a red spring, and changing to different needles doesn't effect the flat spot.

Oh and it seems to happen less in the morning with the choke out, but then I don't tend to flog it when it's cold.

I have this problem too, not really bad but same flat spot then take off at about 300rpm. Be interresting to hear from some of the tuners on here.