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Amal Throttle Valve and Main Jet Size 1974 T100R
#801584 03/16/20 3:32 pm
Joined: Jan 2020
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Lucas57 Offline OP
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I have a 1974 T100R Triumph. All engine parts are stock. Exhaust is a modern day reproduction. I am in the process of buying new 626 26mm AMAL Premier carburetors. I see these carburetors come with a #3 air slide and a 160 main jet. The Triumph published, year/model specific, parts catalogue calls for a #3.5 air slide and a 150 main jet. To complicate matters more the Triumph published year/model owners handbook also calls for a #3.5 throttle valve but calls for a 170 main jet. I realize with modern day petroleum the original specification no longer hold. Any thoughts as to what size main jet and throttle valve I should use here.

Last edited by Lucas57; 03/16/20 3:41 pm.
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Re: Amal Throttle Valve and Main Jet Size 1974 T100R
Lucas57 #801598 03/16/20 5:09 pm
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What I typically recommend to my customers and folks in general is to jet your carbs "to the book"

This is a good place to start...

From there, you can tune your motorcycle and make changes accordingly

Here is a parts book:

https://www.classicbritishspares.com/pages/free-triumph-bsa-norton-parts-books

When it comes down to carbs, you will not get it right the first time, install them and make changes from there

Cheers

Last edited by C.B.S; 03/16/20 5:10 pm.

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Re: Amal Throttle Valve and Main Jet Size 1974 T100R
Lucas57 #801604 03/16/20 5:23 pm
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Hi Lucas,

I've a 72 T100R and I've just fitted new Premier carbs, with the stock #3 and 160 jets. Only done 50 miles on it so far (it's only just starting to feel like spring is not far away here in the UK). However, it starts easily, revs OK and rides OK. I'd say it's not far out - but then I don't rev it too hard so I may not be getting all the way up the carb mixture range anyway. 97 octane petrol.

Re: Amal Throttle Valve and Main Jet Size 1974 T100R
Lucas57 #801669 03/17/20 9:40 am
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My ‘71 on a 626 Concentric ran fine on a #3 slide but is happier on a #3.5. Nothing tangible really just seat of the pants diagnostics. Hot summer running (30c) was easier running.

I think my main is a 160.

When you order the carb get another slide and another jet. Postage will be the same.


'51 C11 in a '54 C10L frame. Back on the road...
'70 Triumph Trophy 500. Next on the bench for a refresh!
'72 Triumph Tiger 650. Back on the road...

Moderated by  John Healy 

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