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Discussion Starter · #1 ·
I have a line on a set of 376 Amals off a T100 that are 1"
I am building a '51 6T that is going to try to be stock, but not all the way and a search shows that 1 1/16th Amals are more in line with a 6T.
I am not going to build a big bore/big cam/big carb motor, but want a solid 650cc of power.

Is the 1/16th difference going to make this possible? Or will there be to little power to cruise highway speeds 2 up?

I have a few steps before I have to worry about firing up and engine, so if I miss out on these I have a year or so to continue the search

 

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Discussion Starter · #3 ·
So the 1 1/16 Amal listed for the 6T would have been the only carb?
Did the Thunderbird ever come with dual carbs? What was the first 650 with dual carbs?
Was it the Bonneville?
900 series at 30mm?
 

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T100 race kit with the delta head , edward turner wouldn't let the bike leave the factory with it fitted , you had to buy the kit and do it yourself , when you fitted the kit the warrantee on the bike was voided , so if the bike blew up that was your tough shit.
The first factory bike fitted with twin carbs was the bonny as far as i know, and they were chopped monoblocks with a central separate float chamber.
An su car carb was fitted for one year on the thunderbirds but not in america, the reason was it got better petrol mileage.
 

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...yes man, you notice the difference if you crank up the engine on the roads.
A friend have a 5TA from 63 with a 22 or 24 Amal and there s a very difference instead of the 26mm when the guy is in top gear
 

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The Thunderbirds had lower compression and smaller cams than the Tiger 110, but my '55 T110 with an iron head screams with a pair of 1 1/18" 376/40 carbs on adapters. You would get way more power out of your motor if you build it to T110 specs or if you want 2 carbs, T120 specs. The only down side is you have the early cases with the small timing side main bearing so you shouldn't flog it too hard.

As for carbs, the smaller carbs may have a bit more grunt off the line but when you open it up at high RPMs you'll want something that can move more air.
 

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The very first '50 Thunderbirds came stock with a 1" carb. It was changed to 1-1/16th during that first year. They were pre-monoblock 276 series carbs with a bolted on float chamber. The 1" monoblock is fine but loses a little top end. It can be bored to 1-1/16th if needed, or put a 928 concentric on it! Anything bigger will be overkill unless you run a later top end or open up the intake ports.
Robbie
 

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The SU only survived one year in the US market because dealers and riders did not like them. They did not understand them and in typical US rider fashion they messed with them too much and screwed them up. They had a great reputation in the UK for mileage and low maintenance once set up properly.
Robbie
 
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