Bonneville America Forums Forums Technical Forums Performance Mods TBS or Thruxton Needles ?

I decided to check the new and improved jetting calculator and it seems that, with my 130 mains, I should replace the stock needles with TBS needles.

However, I seem to recall several people singing the praise of Thruxton needles. If I switch to Thruxton, the jetting calculator says my mains need to go down to 127.5, but I think I can get away with my 130 mains as is. I'd rather be a little rich versus a little lean. I have no shims installed.

So... any thoughts about TBS versus Thuxton needles anyone? How much should I expect the dealer to charge me ? US$8-$10/needle ?

And, if I recall, I should be able to just pop the top off of each carb (yes, I already replaced the screws with SS Allen Head screws) and pull the old needle out and slide the new one in? Will I need to drain the bowl before hand?

Thanks !

Yes, the tops just pop off.
There are springs that jump out so be careful removing the final screw.
No need to drain the bowls.
I replaced stock needles with thruxton needles for no noticable difference, except I got about 30 km's less per tank.
I was running 140 mains with them.
I now run 135 and stock needles, pods...runs hard.

I suggest trying TBS needles (N3RF) first. Thrux needles (NBZT) generally run a full-step richer than TBS. Both needles have a similar profile, however the TBS needles are a bit longer.

I run the Thrux needles and they are thirsty. Gotta feed the beast though.

I tried TBS needles and just couldn't seem to get the mix dialed in the way I wanted so went back to stock.

I run NBZTs in both mine and Karens bike and they made the midrange feel good. My bike runs very strong and Karens did great this year with the new needles and one shim on each. The shim eliminated a poping and long warm up period on her bike.

I run the thruxtons myself.

Thanks all for the input everyone. It looks like Z has an offer, for Thruxton needles, that I'm going to take him up on. We'll see how she runs after I swap out the needles.

Met up with Z at I-90 Motorsports to get the Thruston needles. THey were having some kind of clearance sale with all kinds of bike bits & pieces (Triumph and other) out in a tent with a sign saying to "make them an offer". Saw a couple of used stock pipes and short TORs.

Anyway, after I got home, I swapped out the needles, being careful about the springs. Definitely helps to pull the gas tank when doing this.

But what the heck is that white plastic piece inside below the spring? It looks like one of those plastic things you find ina pizza box so you don't push the top of the box down on your pizza.

Z gave me some shims as well. I considered adding a shim to each, but wasn't sure how you get a shim back out.

Checked one of the spark plugs as well. It looked good.

Put her all back together and gave her a test fire. Started strong with no backfire. I will see how she rides tomorrow.

Thanks again Z.

The white plastic spider is the needke keeper. The spring pressure holds the needle in place. Shims should not be needed with NBZT's.