While holding the throttle at 1/4 for a stretch cut the engine...coast to stop, then pull plug...if blackish then it's rich...if whitish, then lean...


Realize that at 1/4 throttle you are off the pilot (idle) jet completely and more onto the needle and main. If it shows lean and you're 100% positive the pilot is clean & clear (it has tiny little holes), then I'd investigate how the slide/cable is assembled and or take a good look at the needle jet (compare to fiche) to see if you're missing a washer (spacer)...I have a funny feeling your needle is too low into the main (at idle) and causing a starvation issue until you raise it up (manually by moving the throttle)


Your description of it needing to get on the pipe (main jet only) is also telling me there is an issue with the needle...it should be crisp off idle...not need a gradual ramp-up...the more I think about it the more I feel there is something not quite right with the needle and or it's installation (given that you're sure the pilot is CLEAN)...

 

DD thanks for the reply. Yep, just cleaned the jets again two days ago and every hole had light thru it. If I am not mistaken I have the needle clip in the lowest (needle highest) setting. Something is definitely off, when I first got this carb dialed in it would nearly do a wheelie when you went WOT. Now it will jump a little then slowly build speed till you hit a sweet spot and then the throttle gets crisp again at near WOT? At $28 I am tempted to try another ebay special carb.

 

Just thought of something I noticed different. When it is on a jack and I hold the throttle wide open for a few moments it seems to hit a spot where is starts crackling (ignition breaking down) almost like a lean backfire. Do these have a rev limiter?