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Discussion Starter #1
I've heard good things about TBS needles. My question is where do you get them? I see jets and shims on Newbonneville.com but no needles. What does TBS stand for?
 

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TBS=Triumph thunderbird sport. They are the stock needles from that perticular bike, but work good in the twins to enrichen the midrange. But ONLY if your bike has been modded, IE:pipes and unrestriction of the airbox. Otherwise they'll only help to foul your plugs and make your bike run badly. You can get them by ordering them thru any triumph dealer.

[ This message was edited by: dazco on 2006-11-15 15:45 ]
 

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just to butt in here. I intend to do mods most have done to help my bike breath but like kcnlisa, am curious about the different types of needles that can be used.

So now considering the tbs needles to help to "enrichen the midrange", we have one thought from daz to get tbs needles and now gm16sw suggesting Thruxton's.

So my question is, if I keep my own originals will the difference be less midrange response and if so which needles have most gone with. I would prefer to use the most popular as that would suggest to me, various trials from different bikes have determined they are probably the best.
 

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I have tried thruxtons for a couple months combined and i'm using TBS now. the reason is that thruxtons are too rich for most cruisers unless it's had the air box removed. Others have said the same. They're usable, but they're on the rich side and caused my bike to stumble at high revs sometimes. The reason i say go with TBS is because thru extensive testing of both i found the TBS with 3 shims is the same as thruxtons. So if you wanted thruxton needles for some reason, tho unless the air box is gone i can't see a reason, all you'd have to do is add shims. So the TBS gives you the option of enrichening the mids in a very similar fashion as the thruxtons because the taper is very close at the end, but the TBS are longer. So shimming them approximates the thruxtons. But the obvious advantage is that you can lean them out with fewer shims, while with the thruxtons you're stuck with a very rich midrange and no way to lean them out. Mine is as open as you can get w/o airbox elimination and i'm using 2 shims and it's just right. Runs stronger than it ever did with the thruxtons and never stumbles.
 

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hmmm. I haven't had Dazco's problem so I don't know what to say. I guess everyone experiences everything differently. I don't know if it would have to do with the different cam durations between the TBA and the Speedy.

Well whatever. Give the TBS's a shot. Sounds like they are the more preferred pick.
 

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Could be your mains are smaller than mine. If you use less than 130's that would account for it because with 130's and thruxtons it's just too much because they do overlap. You could run thruxtons w/o a problem tho. You coulda run mine with them and thought everything was fine. But if you then put TBS with 2 shims in it and rode it again you'd see the difference. The stumbling i mentioned the limiter. But what was happening was that when i'd hit the limiter the bike would shut down till i was almost to a complete stop and sometimes even die completely. That stopped completely with the TBS and now it just cuts out at the limiter for a second or two then begins firing again. Don't ask me why a richer mix would cause that, but the combination of the that and the way the bike ran it was obvious the TBS worked better. Most people at the BA forum who've tried them also found them rich and now use TBS, so i would always recommend against them for the cruisers if the airbox is still there, modded or not. You might want to try some TBS with a couple shims yourself if you haven't already. You might just get a bit of performance from them. But if your mains are smaller then mine you may be fine. They're on the line depending on the other jets.
 

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I might give the TBS's a try. Can't hurt. Nothing wrong with having a box full of jets, needles and shims in the garage. If they don't work I'll just put them in my lawn mower and have the baddest mower in the neighborhood
 

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Discussion Starter #11
Can anyone give me a logical reason why it calls for smaller jets when you plug TBS needles into the jetting calculator?
 

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On 2006-11-16 13:10, kcnlisa wrote:
Can anyone give me a logical reason why it calls for smaller jets when you plug TBS needles into the jetting calculator?
the needles sit inside the main jet and gradually come out as the throttle is turned till at full throttle the needle is more or less out of the jet allowing it to be fully uncovered. So they are interactive, or in other words one's size affects the other. It's a balancing act. say your bike is just right with 125 mains and Thruxton needles. If you then went to TBS needles which aren't as rich, the mains would need to get larger and richer to keep the balance. When at full throttle even tho the mains are said to be on thier own, the needles are still adding some influence and visa versa. So if you increase your mains, the hole is bigger and therefore the needles would let more mixture thru so you'd have a richer midrange w/o even having changed the needle length or taper. This is why you're supposed to get the mains right before trying different needles/shims. Hope that was clear...the best i can describe it at the moment.

[ This message was edited by: dazco on 2006-11-16 15:58 ]
 

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I use TBS needles w. one shim & I have nary a drop in mid-range. Certainly nothing I can feel.
 

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You would think someone would have run a dyno jet & made one change at a time with all the needle,jet combinations..and got the bike right...
I just ran a dyno run on mine to get a base line..
the bike has freak box ,kn's nology coils,iradian plugs,nology wires,BuB pipes,18 tooth Primary gear. Thruxston needles with 2 shims.
60.9 HP 45.88lbs of troque.
the air ratio shows 13 to 1 Except it has a rich spot starting at 4500rpms dropping down to 12 to 1 going to 6000 @ 6000rpms it's back up to 13 to 1 going to7500 then climbing to 13.8 to one at 7900rpms.

I am thinking of either pulling one shim out or taking one baffle out of the bubs..the more i think about it -I am leaning toward the baffle...either way...I am back on the dyno jet....

Is there a way o have this site send a email when a post is made on a subject?
thanks,
Kenny Nichols
[email protected]
 
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