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tbird sport carb rubbers for tbird & legend

8K views 14 replies 7 participants last post by  jimmyj900 
#1 ·
What's this all about?? What would it do to my bike if I swapped to TBS carb rubbers??
 
#2 ·
What's this all about?? What would it do to my bike if I swapped to TBS carb rubbers??
The primary differnece between the Thunderbird and the Thunderbird Sport horsepower wise is an exhaust balancing pipe and the thunderbird had restrictive carb rubbers. The rubber manifolds that connect the carb to the head had a restriction inside in order to reduce power. Essentially, If you remove the restriction, you have a TBS engine with no balance pipe on the exhaust. It will not get you to the TBS numbers but it will improve your horsepower.

Frank
 
#6 ·
MMmmmmmm TBS carb rubber... aaaaaaggggggg.
Doh! Stupid spell checker. ( :eek: (|).

I suppose anti-rejection drugs would be the order of the day.

Alright, I'll try again.

Is it necessary to re-jet after this or is that required only for the Air box Modifications.
 
#7 ·
The nearest dealer where I live stocks them. I thought they all would so maybe I'm spoiled. As far as I know they are the same on all the classics. My '99 Legend came with unrestricted carb rubbers and had #98 main jets and #38 pilots so there should be no need for rejetting. However, if you are going to pull the carbs out you should consider a jet kit, venting the airbox, and aftermarket pipes.
 
#8 ·
Called my dealer and asked about the rubbers. He could only find one set for the TBS but several for the t-bird depending on year and so on. Now I know that the t-bird went from Mikuni to Keihin...what about the TBS? Did they stick with the same? Which one in that case? Does it matter? Will the rubber with no matter if its a mikuni or keihin?
 
#9 ·
Called my dealer and asked about the rubbers. He could only find one set for the TBS but several for the t-bird depending on year and so on. Now I know that the t-bird went from Mikuni to Keihin...what about the TBS? Did they stick with the same? Which one in that case? Does it matter? Will the rubber with no matter if its a mikuni or keihin?
The first thing is to determine if you've got the restricted carb rubbers. They were only installed on the Mikuni carbs, so if you've got Keihins you don't need to change anything.

To double check, look for dimples in the sides of the carb rubbers about the diameter of a cigarette. If there are no dimples, you don't have the restricted carb rubbers.

The carb rubbers for the Mikuni and Keihin carbs are supposed to be slightly different lengths and diameters, so it's probably a good idea not to mix from one carb type to the other. (Haven't checked that personally.)

I believe it was the Super3 or Speed3 that used the unrestricted rubbers so have your dealer check on those for the same year of your bike.

Also, the dimple might be shown in the fiche or computer, but I'm not certain of that.

Jim
 
#10 ·
The first thing is to determine if you've got the restricted carb rubbers. They were only installed on the Mikuni carbs, so if you've got Keihins you don't need to change anything.

To double check, look for dimples in the sides of the carb rubbers about the diameter of a cigarette. If there are no dimples, you don't have the restricted carb rubbers.

The carb rubbers for the Mikuni and Keihin carbs are supposed to be slightly different lengths and diameters, so it's probably a good idea not to mix from one carb type to the other. (Haven't checked that personally.)

I believe it was the Super3 or Speed3 that used the unrestricted rubbers so have your dealer check on those for the same year of your bike.

Also, the dimple might be shown in the fiche or computer, but I'm not certain of that.

Jim
Hmm..let me get my head around this, with your help I hope. I thought we were talking TBS carb rubbers...what's super3 and speed3?? I guess you're talking Speed Triple...but would those rubbers also fit??

I have the Mikuni carbs on my 97 (actually late 96 but not taken out until 97) T-bird. Will the dimples show on the outside of the rubber or just on the inside?

Oh dear I feel dirty talking about these dimpled rubbers...but but...anything for xtra horsepower!
 
#12 ·
On 2005-08-10 13:31, 95TBird wrote:
They will show very prominately on the outside. It is more than just a dimple actually. It is a pronounced hole a good 1/2" deep or more. A quick glance at the connection between your carb and the cylinder head will tell you.

Frank
Hmmm...don't think I have the restricted ones. No dimples or holes as far as my eye could see...I did however not unscrew the clamps and look under them. Are the dimples/holes lurking under them perhaps??

Now, if the major difference between the t-bird and the tbs only was these two things i.e. balance pipe and carb rubbers...how does that explain the 70hp vs 83hp? I mean if the later t-birds had the same carb rubbers as the tbs...that should have accounted for more than the stated 70hp....or did the early t-birds have less than 70hp since they had the restricted rubbers??? I don't get it?
 
#13 ·
Be careful here, fellas - I have heard, but am not sure, that the Keihin rubbers are longer than the Mikunis (due to differences in carb dimensions). This would mean that you will have even more fun fitting up your air box....

I used the part number for Trident intake rubbers. I understand those off a "steamer" Tiger are also to same.

Scot

[ This message was edited by: cafetbird on 2005-08-10 16:46 ]
 
#14 ·
Now, if the major difference between the t-bird and the tbs only was these two things i.e. balance pipe and carb rubbers...how does that explain the 70hp vs 83hp? I mean if the later t-birds had the same carb rubbers as the tbs...that should have accounted for more than the stated 70hp....or did the early t-birds have less than 70hp since they had the restricted rubbers??? I don't get it?
It is my understanding that the TBS's may have been a bit over rated originally and then in 1999, when they changed the carbs, the TBird was actually upped in power as a result of the unrestricted rubbers but the specs were never changed.

Just my opinion
Frank
 
#15 ·
Hmmm...don't think I have the restricted ones. No dimples or holes as far as my eye could see...I did however not unscrew the clamps and look under them. Are the dimples/holes lurking under them perhaps??
The dimples are quite visible from the outside and are between the clamps.

As I understand it, the dimples were designed into the Classics models (along with the single inlet airbox) to keep the horsepower at 70 or below for the German market where there were some sort of insurance or license class restrictions.

Having the dimples visible (and deep!) was to insure compliance for vehicle inspection and prevent folks from cutting the internal restriction out of the carb rubbers.

Jim
 
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