Bonneville America Forums Forums Technical Forums Performance Mods Sputtering

I put a shim on my TBS needles today and resynched the carbs. I also did 3 1/4 on the mixture screw. Now my popping is gone, but I have a sputter right at about 1/8 throttle for a little, then if I twist some more, it goes away. Any ideas? Also, does the mixture screw have anything to do with synching the carbs? It seemed very difficult to get the levels right for some reason, wasn't a problem the first time. My setup: Sceptres, TBS needles, K and N in box, no snorkels, 130 mains, stock pilots.

You mean screws plural, right? I found if I eliminated popping on decel completely, it was too rich.

Shimming the needles pulls them out sooner, increasing the wet side of the mix. I have read that the hotter iridium plugs "fix" this. Bottom line- you're rich off idle. Get more air into the mix. You didn;t mention your elevation, but even at Sea Level you are above outer limit with the 130. Several things to try, easiest to hardest: 1) remove the shim, 2)Go down to a 128 main, 3)cut the intake box up and add dual filters and rejet up main and pilots, 4) find a replacement air box eliminator and rejet up main and pilots. The factory box is very restrictive, even with the snorkle out. If you are not willing to mod the air box, and you are happy with the performance, remove the shim and you are done! Check out Daniqua's jet sizing tool and run through the scenario's. ~ peace

Thanks guys. I will go back to needle with no shims. I am going to Freak the bike soon, when I get some more funds.

Don't waste your money on the irridium plugs. Just side gap your stockers. .7 gap at a 45 degree angle (http://www.performanceunlimited.com/documents/plugsidegapping.html )
I'd say lose the shim. Readjust your mixture screws for best idle (http://www.bonnevilleamerica.com/forums/showthreaded.php?Cat=0&Number=99368&page=0&vc=1 ) then synch your cabs with a carb tuner (http://justkdx.dirtrider.net/carbtuning.html ). Remember when syncing the carbs only turn that screw a pubimeter or you will get all "screwed" up.

Keep in mind, when you Freak your gonna change everything.