Bonneville America Forums Forums Technical Forums Performance Mods OK...1 more time pls...TBS vs stock needles

guys, i'm pretty confused... ...i've read many differing opinions on this subject...some say TBS needles, no shims...some say shim the TBS needles cuz they're too long...some say use Thruxton needles, and others say the bike'll run too rich...can i get some feedback from guys that are using TBS needles w or w/o shims? also, while i'm at it...what about vaccuum port drilling? i thought i'd do that at the same time, but want to make sure there's a definite benefit to it. any probs encountered by those that have done it? btw, i use the term guys in a non-gender specific way...

everyone has different set ups weather it be pipes, airbox mods, or even where they live has major effects. best bet, try needeles, then try shims, if you can get one a dyno tune could tell you everything you want.

Frank

I agree with Frank.
I am running your setup exactly on an '03.
I had what I considered slow mid-range response.
Installed the TBS needles/no shims and noticed a good improvement in this area.
Have not added any shims and have not drilled the slides yet but will try both of these....one at a time to see if it makes any difference.
BTW...I am at 625 ft above sea level

You see my setup in my sig. I am darn near at sea level in a southern climate. So take that into account.

After all the other work I did, I noticed a flat spot in my power band at around 4500rpm. Not a loss, just not as linear. Switched to TBS needles and that went away. Have not shimmed because I do not see the need, for me. If you do not have this issue, there is no need to change!!

The only thing drilling the slide's vacuum port with a 7/16 drill bit will get you is a crisper throttle response and that's a good thing. This would help everyone, IMO.

I believe it was Dinqua who tried Thruxton needles and found them to be too rich. I do not remember if this was before or after his BB.

crap... I am usually pretty good at proofing my stuff and I use the preview function a lot.

Yeah, I would suggest NOT using a 7/16 bit!!!

7/64 is definitely what I meant....

I pretty much followed Phil as my guide since I'm at about 6 feet above sea level myself, altho a more northern climate. So far so good with TBS needles. May try 155s instead of 160s soon. The best thing about the needles is they are CHEAP and EASY to change. That's why I reccomend them, not because they are the cats balls, but because it's such a cheap and easy experiment. And I'd bet you could sell them to someone if you didn't like them.
Edit: I also drilled the slides while I had the tops of the carbs off. Simple, real easy to do, just de-burr the hole a little with a larger drill bit (by hand) when you are done.

My carbs are runnning stock needles with one shim and, along with jet adjustments, dyno out real well. No drilling and no TBS needles. Have a tuner set them up with the assist of a dynamometer. It's the only way to go.

Here's the deal. the reason some benefit and some don't is becase as i said before, TBS needles are longer than many needles. therefore, if the taper isn't much richer than the one in your bike, the length may actually make them overall the same or even leaner. Example: the needles in my speedy were tapered a bit thicker, BUT, they were considerably shorter. So with the longer TBS, at any given point in the jet the thickness was probably the same or even thicker. Look at the pic below and it should be clearer. Use the red line as an example of a given point of the needle within the jet. Even tho the needle on the right (TBS) is thinner tapered as you can see by the tip, because it is longer, at the point within the jet where the red line is the TBS is thicker. Shim it and it wont be.So it depands on the length compared to YOUR current needles

That drawing is a bit extreme. Below is a pic of all three needles and I finally found the post by Deuce where he measured both the stock and TBS needles in 5mm increments (there was no Thruxton at that time). Here's the page in the archive:

http://www.bonnevilleamerica.com/message...echnical%20Talk

and here's the dimensions in mm. Clearly, the TBS is thinner everywhere and would therefore be richer overall. Shimming may or may not enrichen the main circuit too much. Also according to Deuce, the TBS needle is 3mm longer than stock.

TBA ---- TBS
2.48 --- 2.44
2.48 --- 2.44
2.46 --- 2.42
2.42 --- 2.39
2.32 --- 2.27
2.21 --- 2.16
2.12 --- 2.05
2.07 --- 1.92
1.98 --- 1.85
1.91* -- 1.70
--------- 1.60*

(*) = tip

OW,
May I call you OW?

Anyway, I'm running 130 mains, stock pilots, AI gone, snorkel gone, stock air filter, Thunderbike pipes, 18t front sprocket, TBS needles with no shims, and I drilled the vent hole in my slides. I'm happy.
I should have kept notes as to the order of the mods, but I didn't. But, I had a problem with popping on decel that I just couldn't get rid of, and it was intermittent. I even had a problem with the engine "napping" if I blipped the throttle while downshifting through the gears - it would not rev if I was downshifting quickly. That is when I put the TBS needles in and those problems disappeared and the mid-range and upper end of the throttle felt stronger. I was happy.
I read the vent port drilling thread and waited quite a while before I got the nerve to try that. It made the throttle response somewhat "crisper". I am still happy.

Point is, after each mod, without a dyno available, I synched the carbs and checked the plug color and was seat-of-the-pants happy. I don't need to squeeze every last ounce of hp out of this bike to be happy. I'm at about 750 ft. above sea level, 6' tall and 185 lbs. My favorite color is black and chrome, and if I win I will promote world peace and solve world hunger.....

Do yer mods 1 at a time and see if they work for you.

Your results may vary......

My point is that the difference between the needle lengths is 3mm (as measured by Deuce), or .11", or less than 1/8". That is not a lot and therefore do not stick down into the jet much further than the stock needles.

Also considering the OD dimensions of the TBS needles is less (more taper), an unshimmed TBS needle will produce a richer main circuit.

For grins, I did the differences between Deuce's data points

TBA ---- TBS --- diff -- " conversion
2.48 --- 2.44 -- .04 --- .0015"
2.48 --- 2.44 -- .04 --- .0015"
2.46 --- 2.42 -- .04 --- .0015"
2.42 --- 2.39 -- .03 --- .0011" -> (I suspect an anomaly here)
2.32 --- 2.27 -- .05 --- .0019"
2.21 --- 2.16 -- .05 --- .0019"
2.12 --- 2.05 -- .07 --- .0027"
2.07 --- 1.92 -- .15 --- .0059"
1.98 --- 1.85 -- .13 --- .0051" -> (I suspect an anomaly here)
1.91* -- 1.70 -- .21 --- .0082"
--------- 1.60*

* = tip

Well, all I'm trying to get across to him is that the TBS length WILL in fact be longer than some people's needles enough so that they will not enrichen the mix, or at least not enough to feel any difference. And others will have needles that WILL make TBS needles give them a boost. The proof is in my bike right now. TBS needles didn't make one bit of difference for me. Then i shimmed them and they gave me more power than the stock needles di at thier max, which came at one shim.

As to the actual dimentions, i don't know that you can say "X" of needle #1 is only "Y" more than that of needle #2 and to discern that it won't make a difference unless you happen to know how much a thousanth of an inch might actually make in fuel delivery. For all you know the size difference you quote while seeming like little to your thinking may actually be a considerable difference in fuel delivery. I've looked at the 3 sets of needles i have and as far as thickness it's very hard to see yet it made for huge differences for my bikes performance.

thanks everyone (and I absolutely mean EVERYone) for the feedback and info...keep it coming...the differing opinions are very useful and informative and i find the discussion intersting...i'm coming to the conclusion that, while i can't specifically say that i've noticed a mid-range power flat spot, i'll try the TBS needles and see how she runs...i believe i will also do the vaccuum port drillng to achieve that 'crisper' feel...my needles have arrived, and the weather is mild, so what the hey, eh? i'm also considering either a Freak or some further airbox mods, which may lead to another rejet...but first things first...appreciate all your responses...

Grump, if you have to shorten my name to just 2 letters, i suppose O and W are the logical choice...i mean, A and B wouldn't fit so well, and A (alpha) and Z (omega) might be a bit presumptious...i also answer to just plain and simple Wolf...some of the names my wife calls me when she's in one of her moods (which i absolutely had no part in creating! honest!) we'll probably not consider...

OldWolf,
I put in the TBS needles with the goal of eliminating the "flat spot" in mid range acceleration. Goal accomplished. The dyno said I was a little rich through the mid range with TBS needles, where I had been very lean with stock needles. The extended tip of the TBS needles is mute because the head of the TBS needles laid flat on my plastic spacer under the spring. The lift will begin at the exact same time as with stock needles, but the TBS needles having more taper will allow more fuel earlier. The TBS needles extend into the jet farther but the taper at that point allows the same amount of fuel as the stock finishing nail. There was no difference in throttle response, but the midrange pulled much harder. Low end performance along with top end were unaffected. I think some will argue that the TBS needles are usless in our bikes. But, experience beats an argument every time - hands down.
Put in the TBS needles for a smoother power curve and drill your slide vacuum hole to 7/64" for a faster throttle response. You'll be smilin'.

Was that with the Beastie Boys on in background singin'...

Most illingest b-boy Well I got that feeling
I am most ill and I'm drillin' and chillin'

Don't the '05s have a larger hole from factory?

That has been said on here, yes.

AND the 865cc Speedmasters also have different needles. So a lot of this talk when comparing the 03/04/05 is becoming moot as the differences are entering the forum of discussion.

So now you're saying that there are 4 possible sets of needles we could use? How much difference are there between the new Speedmaster needles and the rest?

I went through this last spring. The following was my final posting on the subject:

When I last posted, I was waiting for TBS needles ordered from the local Triumph dealer. I put the TBS needles in last weekend and finished tweaking the pilot screw adjustment this weekend. I could not asked for better results. Runs great running up through the gears and at all throttle poditions in between. There is virtually no popping and backfiring on deceleration. Current modifications and setup are: EPCO pipes, AI removal kit, Freak, 160 Mains, 45 Pilots and TBS needles with no shims. Pilot screw adjustments are at 2.5.

That's really good info. I am much more north, but I am similar elevation. I just got my 45's the other day, otherwise our setups are the same!

Okay, I understand the advantages to the TBS needles but what are they and where do they come from?(TBS stands for?)(Triumph part number?)
Thanks!!
Phil

Jet - Needle Thunderbird Sport #T1241024, $8.95 each at my local dealer.

TBS = Thunderbird Sport (Triumph)

The Triumph part number I used is #T1241024

Thank You!