Bonneville America Forums Forums Technical Forums Performance Mods TBS Needles - Shim(s) or not?

Folks:
My TBS needles should be in next week. ($16 from my local dealer) Wondering if I should put on any shims? My setup is:
SS Long Cannons
132.5 main/45 pilot
Uni Filter - w/all snorkels removed
Currently, I have two shims (installed when I rejetted for my old TOR's)

AL...
Have orderd a pair myself, & based on everything I've read (Archives, etc.), no shims are needed.

Not to disagree with BonnyBeemer, but Deuce, who originally did the TBS setup did use a shim on each. But, it seems all of our bikes are a tad different, so better have a pair just in case, and if you don't need them, no big loss. I'm going to start with them when my TBS needles come in and see from there. It's a relatively easy change, so no biggie...

We didn't use shims on my son's Speedy (Bubs slash cuts [jetted by dealer at sale]; snorkle out)

Yup, with carbs, "your mileage may vary". Here in the Phoenix area, at about 1200 ft. ASL, we have days in the winter where the density altitude is around sea level, and days in the hottest part of summer, where the DA gets up over 6000 ft.(!) ASL. Tuning for those kinds of changes can be slightly tricky....

Thanks for the replies folks. I'll try one shim and see what happens. Good point on elevation PapaDean. I'm a few hundred feet above sea level here in MD and assume I don't see the kind of swings experienced in AZ.

I'd run down to a local dealer and see if he'll give you a few old shims from used dyna jet kits. Given your smaller main jet size, you could probably go one shim...but if you need to go up two, you might see better overall performance by going up a main jet size with no shims at all.

Guess I'll have to tinker around a bit. Thanks for the good advice guys.

I'd be surprised if you need a shim. Let us know what happens. I think somebody here posted that they tried a shim and it didn't run right, then they pulled the shim and it ran better.

PapaDean, can you tell me what size jet setups your son is running, since I also have Bub slashcuts and snorks out? Thanks!

That's one good thing about this Al, it's only about a 20 min. job to change from with or without shims, so not a big deal.

Skip the shims Al, you most likely won't need them. but, try them if you will, then see how she runs. We are all different as stated above.

for what it's worth I didn't put in my shims, but I did have two shims in my previous setup...

I'll start with no shims and take it from that point. Pretty easy to change so no problem. I'm getting curious as to what changes the needles bring.
My new front tire is on the way also. I've got a serious headshake at 40 mph up, my tire must really be shot. Obviously I'm not riding much until the tire arrives next week as well.

Popped the TBS needles in last night, didn't add any shims. Went to a nice long test ride tonight.
The Good news is:
Throttle response is perfect, no idling problems or lags on short bursts of gas, nary a hiccup
The Bad news is:
Those are the same results I previously had with the OEM needles and two shims. I can notice exactly zero difference on any riding condition.
I was a little disappointed, but given I had no problems previously maybe that's all I could have expected. I'm glad they were only $16 for the pair.

Well you're right they are a cheap experiment!! You didn't notice any difference in the power curve? Lots of people who had a flat spot sait it fixed it, me included. Maybe you were just real good or real lucky with your first setup not to have that flat spot!

Well since my front tire is bald, I didn't take it past 70 mph. Maybe I'll notice something on the upper rev range, but cranking through the gears the bike pulls the same.

I'm sure you could get all your money back selling them here. I'd say several people would be glad to take them off your hands.

Try winding it out to 70 in second and see how it feels all the way up. And yeah I'm sure someone would pay fill freight for them if you wanted to take em out!

I'm surprised you didn't notice the same difference the rest of us did.

My new front tire is getting mounted tomorrow. I'll get in a few hundred miles over the weekend, heading down to the British Bike show near DC on Sunday. I'll see how she runs with two-up at highway speeds. For $16, probably not worth removing.

Al,

The more agressive taper on the TBS needles seems to cure a slight stumble or flat spot at midrange rpms for most of us. However, most of us (as far as I know) never used shims on the stock needles. By using shims on the shorter stock needles, you were probably achieving the same result where the jets flow's overlap at midrange.

Look on the bright side. For $16.00 you have 4 less pieces in your carbs to deal with and that much less weight to haul around!

Well that makes sense! Tire was mounted today, looking forward to really giving the bike a work-out.
Al

Well Al, I finally got around to checking my plugs with one shim under the TBS needles, a bit too rich. So, I pulled the shims, and while at it, turned the Pilot mix screws in a bit (the right is at 2.75 turns, left at 3 even, as the right seems a tad richer than the left. I already ran it up the street at WOT and didn't notice any issues up to 70mph with acceleration, will ride again tonight and see what leaning up the pilot screws (they were at 3.25 turns) does, I suspect it should be fine, hopefully no noticeable difference on popping (which was up till now much diminished with 3.25 turns and TBS/1 shim setup....

I've always wondered why my bike runs slightly better in the winter here in Tucson, than it does in the summer. I imagine we get some of the same density altitude changes that Phoenix does.

In 3 weeks I'm heading to Alpine, Az. I wonder if it'd be worth doing a main jet change to adjust for it. I'll only be gone 4 days though. Been up that high a few times in the past and I really notice the bike losing performance at 8,000 ft.