Main Jets and Compression Questions

[Sludgetrap]

 :-[G,day Guys,,,

I,ve asked these questions on a couple of other forums but havent got an answer from anywhere yet .
So what I would like to know is , can any of you guys tell me the compression for a 1970 T100C and same year TR6C, stock barrels and pistons, 9.0 to 1 from memory compression ratio, out of the box, meaning new specs.
And the other question is , some of you guys here know that I,ve got the above bikes amoungst others and that the T100C is a twin carb, and before everyone says Wrong, thats how it was ordered from the factory for the West Coast of the USA by Jo Mo.
What I,m trying to find out is the correct main jet size for the twin carbs, I,ve looked online and in two different workshop manuals that I have and have found 4 different sizes.
I just looked up under daytona but found such a big variation
Now I could buy 20 or so jets and start testing but I would have thought there would be a spec somewhere, or at least two places that said the same size so I could use as a starting point,,cheers and thanks in advance,,,

[Goldy]

The Amal reference book does not show a 1970 100C but for 71 - 72 it lists R626/32 carb with 376/100-170 main jet.

[esometisse]

I am afraid you WILL have to buy some main jets of different sizes to get your T100C running sweetly.
If not for the fact that there are indeed several different carburetor setup instructions for the twincarb 500 unit Triumph around but for the fact that this is an engine in a fairly highish state of tune that can show quite a lot of variation from one individual engine to the next - both assembled from presumably identical parts!
From 1968 all twincarb 500s used the 626 Concentric, and according to Roy Bacon the recommanded main jet sizes over the years are: 1968-200; 1969-160; 1970-180; 1971general-150; 1971UK-170; 1972-150!!!!!!!!!
That won't help you one bit!
Furthermore, if you take into account that the fuels used 40 years ago are vastly different from the fuels used nowadays you don't really have any other choice but to find out for yourself what size(s) your individual engine needs!
So get some sets of jets, start with 180s and go down gradually in steps of 5 until you've found out!
And don't be surprised if you find out in the end that you need slightly different sizes for left and right!

Cheers
Andy

[Sludgetrap]

G,day and thanks for the input guys,,

Seems I might have the wrong carbies on the bike , I have 28mm Concentics matched to the manifolds something I,ve overlooked forever, and after being made aware of the fact I,m supposed to have 26mm ,so heres hoping that this may be half the problem.
Bit of a dummy I know but just didnt enter my head,,,
I think I,II be up for a new set of 26mm and 180 main jets,, will keep you posted , thanks to ecomitissie and Goldy ,,cheers,,