Bonneville America Forums Forums Technical Forums Performance Mods TBS needles=performance or driveability?

I know TBS needles improve midrange performance but do they have an affect on everyday driveability? For example, I have a somewhat flat throttle response when making small increases in throttle at 1/4 to 1/2 throttle. Will the TBS needles help this condition?

I noticed 42 pilots in your sig. How many turns out on your screws? I had similar pipe and airbox mods, ended up going back to stock pilots with screws out 3 1/2 turns.

I put my TBS needles in specifically to remove that same flat spot of which you speak!...Worked great!

My screws are out 3 1/4 turns if I remember correctly. Lately I have been trying to get a good balance between MPG and driveability. I am not so much concerned about performance but it seems to be faster than it has ever been where I am right now. But my plugs are also white with a little tan color on one side. And it seems to run like it's lean too. My mileage is up to 38.5 so I hope I don't lose MPG by going to TBS needles.

Amazing how different all of our bikes are - for example, that mileage seems low.

I run SS exhaust, modified airbox / UNI, 130 mains and 45 pilots (about 2.5 turns on the screws) and get ~42 normally (a LOT of heavy traffic in the DC area commute). I just got 47 MPG at an average of 80-85 MPH (indicated) on a round trip to Richmond last weekend. Guess I must twist my wrist a little less.

I twist my wrist hard when I can and I still get close to 50 mpg most of the time. I run Freak , 155 mains ,48 pilot, open stock exhaust, and no AI. Quite a bit of mileage depends on fuel too. The ethanol blended fuels tend to lower mileage and that is proportionate to the amount of the blend.

We run 10% ethanol here and I know that is having an affect. I'd be tempted to run to the next county sometime and fill up with "real" gas and see what my mileage is then. Looking at my plugs and the way the bike is running I know I am lean. But 38.5 mpg is the best I have gotten yet.

I get 43 with plenty of throttle twist. I've noticed long, high speed runs seem to eat more gas than spirited around town riding.

Yes, I balance the carbs everytime I make any carb mods. I was thinking of drilling my slides when I put the TBS needles in. Thanks Erwin.

I get 33 mpg with my bike all the time every time. I have the tbs needles it helped with the flat spot somewhat its time to shim it cause I still have some flat spots.

I found the TBS needles to be a big improvement over stock. I did end up bringing the main jet size down from 130 to 125 (thinking of trying 128, though) after puttin in the TBS needles. I'd give it a try, its relatively easy to do and inexpensive.

Same boat here, Rick.
Stock needles, no shims.
White porcelain no matter what I do with mains, pilots, or screws.
Thinkin' TBS needles are called for.

Bill: They weren't always white. I had 135 mains, 45 pilots, and one shim with a stock air filter. The plugs were black. I also was getting 25 mpg. I've backed everything down one step at a time to where I am now. Also added a Uni. It runs like a rapped ape now at WOT but under normal driving it's flat and feels lean. My mileage is better so I hesitate to make any more jet changes. I'll see what the TBS needles do. At least it doesn't involve pulling the carbs again. That's getting old.

For what it worth, heres my set up,

130/42/TBS no shims/Drilled slides/3.5 turns/Uni/Thunder bike pipes/42mpg more local than highway driving

Don't the '05 slides have bigger holes already?

Mine is an '05 and mine were not at 7/64". I drilled them. However, my ID tag says that the bike was built 07/04.

My setup is similiar to Erwin's, and I get 44 mpg. Half local, half highway driving. (42 pilots)

Just fitted TBS needles, 125 mains, Uni and dumped the snork. Pilots still 42 at 2 1/2 turns. 865 motor ('07). Plugs are light tan.

The TBS's helped midrange a lot and made the biggest improvement over my initial stock needles with 2 shims. Still a little flat below 1/4 throttle though, I'm thinking of drilling the slides this weekend to address this.

Problem is this last step is the first that's non recoverable and I'd hate to screw something up.
Does it make much difference?

Larry

Read pages 4 and 5, learn all you need to know about needles.
Mikuni Tuning Manual

Thanks Dinqua,. What would we do without ya..

Far as I know, most of the later 05s and all newer bikes already have their slides opened up. I doubt that you need to do this. What this was for on the earlier bikes was to improve the initial throttle response, as in it gave us a little better snap off the line.

Drilled to what? (hopefully Patrick will chime in)

Yeah, I drilled them to 7/64, or whatever the Triumphant artice said (can't remember the exact measure anymore). Anyway, it only took off a very small amount on metal, so its possible that the newer bikes come from the factory with a bigger hole. I didn't notice too much difference either positive or negative. So I don't think it hurts to drill out the hole on the newer bikes, but you may not get as much of an improvement as on the earlier bikes.

Also, Larry, not sure what pipese you are running. I have short TOR's and went down from 130 mains to 125 with the TBS needles drilled airbox, Uni,etc., and although that cured the rich condition I had with the 130's, I ended up putting a shim under the needle to richen up the bottem end a little. So far that combo (#125, TBS, 1 shim)is working pretty well. You might try it just to see, its pretty easy to add or remove the shims.

I'd be interested in knowing what the slide holes are stock on the new bikes.

The old ones were 2.5mm (0.098").

I put TBS needles in mine as well as drilling the slides. It seems to run better under normal driving conditions. It's more responsive to small throttle increases. But it still seems lean. On cold days it just seems a little flat at times. I hesitate to shim them due to my already lousey mpg. But since the TBS needles are longer maybe a shim won't have too much of an adverse affect on mileage. It's easy enough to try anyway.

Thanks gilligan,
Running long TOR's and Yes, I found exactly the same with a shim and the TBS's. I'm thinking the 130's might be about right though, the 125's seem a little lean.? Maybe try a change this week.

Didn't attack the slides last week, went riding insted.. But I reckon the '07 slide holes are a tadge under 2.5mm. I think a 7/64 drill will only take off around 10 thou (I know I'm mixing standards here but you get the drift.. and it caters for all tastes...).

With 130 mains, stock needles with one shim, and 45 pilots I was getting 25 mpg. Now with 128 mains, no shims, Uni, and back to 42 pilots I am at 38 mpg. I'm not sure if the TBS needles had any affect yet. Haven't had a chance to ride in the last few days.

thats a big difference

I had 130 mains and 45 pilots after putting on the Specialty Spares 2 years ago. My dealer on my 2 year service drilled the slides and put in adjustable needles and did pre/post dyno runs. They ended up changing the jets to 125 and 42 and I have no snorkle with a UNI filter. The bike is running better than ever and my gas mileage has gone up from 34 to 38 (avg. city/hwy).

I'm not sure if the needle change or drilling allowed going back to smaller jets, but I'm not arguing with success.

I just thought I would update everyone. After installing the TBS needles and drilling the slides over the weekend I got almost 41 mpg with this last tank. (Read my other posts in this thread.)That's a relief!!! I think I am going to leave it alone. It's runs good and pulls strong through all gears. I am a happy camper.

glad you got it figured out.