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Which Triumph Motor for my TFS?

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  • Which Triumph Motor for my TFS?

    Hi,

    I'm seriously considering installing a Triumph motor into my TFS, mainly to make it more suitable for the roadwork element of Long Distance Trials.

    Which is the best motor and carb for this application? I'd still like to keep the machine 'pre-65' compliant.

    Where might I obtain suitable plates for mounting the new motor?

    If I obtained say a road bike motor, are there any recommended tuners who could make it more suitable for trials use?

    Thank you,

    Ian.

    PS I will hold on to all the original parts and would look to keep the conversion reversible.

  • #2
    TFS Triumph-Greeves

    Triumph 350/500 C range. A really easy conversion using simple plates which can be reversed.

    Private message me with your email and I will give you details of engine plate patterns.

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    • #3
      A standard T100 engine will give you great power for what you want. Only one carb and standard compression (Don't go Daytona!!!!) If you want a bit more sparkle, the sports exhaust camshaft and a polished head was a usual mod. No doubt someone will give you all the relevant parts numbers. In my (much) earlier years, I rode several bikes with a similar engine spec to this and the increase in pulling power is noticeable.

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      • #4
        Here is a couple of photos of Phil's engine plates holding my T100C. Excellent job by Phil. As to the engine I went for a later engine (T100C) as it has, I believe stronger/better bearings on the crank. I suppose technically I could not use my one in pre 65 but then it has been designed for distance not trials. It is probably best to design it for one purpose rather than trying to fulfil a number of roles as then everything becomes a compromise.
        Great bikes









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        • #5
          Wise words

          Cheers Tony. Wise words indeed. I have championed the twin plate set up for the TFS. Still got ideas to remove the bottom engine mount and improve ground clearance. Equally, a hydraulic clutch.

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          • #6
            Hydraulic clutch My engine was rebuilt by SRM so not a cheap job, one finger clutch one hand, really heavy- I would like a hydraulic clutch Phil
            Perhaps electric start for those days when the knees are not working too well

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            • #7
              Thanks for the replies.

              I have the small matter of acquiring a motor first

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              • #8
                try the Malvern jumble , expect to pay @ £1000 if its complete , the 3ta is in a softer state of tune and very smooth , the t100ss is a lot faster , you might consider a B40 unit

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                • #9
                  Originally posted by ian640 View Post
                  Thanks for the replies.

                  I have the small matter of acquiring a motor first
                  A 3TA (18bhp) can be easily converted to a T100A (32bhp). The differences are Barrels ,Pistons,Cams,Rods,Head,Clutch basket,carb. That's 9/1 com.The 5TA is softer and 28bhp. The big ends are shells so its easy to change the split con rods.A big improvement in performance.

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                  • #10
                    Versatile engine range

                    The C Range engine is a real Meccano set when it comes to mixing parts and specifications. Aside from the major change from BSF/Whitworth to Unified the possibilities are endless. Cub pistons fit straight onto 3ta rods so with a small oversize re-bore you can have a 400!

                    Distributor engines can be upgraded to points on the side, etc. I could go on......

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                    • #11
                      Phil. Out of interest, what year did they change from BSW/Whitworth to Unified? Interesting also about the Cub pistons; a simple and relatively inexpensive upgrade to the 3TA motor, which one would imagine are cheaper and possibly more readily available? Does that just give a bit more low/mid-range power than the standard 350, rather than bringing the characteristics closer to that of the 500? What CR does it give?
                      Ian

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                      • #12
                        Triumph

                        Ian

                        The thread changed in 67/68.

                        The compression ratios follow the standard cub ratios. 9 : 1 being the most useful. The combustion chambers will need to be opened out on a lathe .

                        As you say, the 350 engines were more popular.

                        The 400 gives a bit more power without the drama of the 500.

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                        • #13
                          Good info Phil; many thanks. Ian

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                          • #14
                            Hi Phil/Ian, having not had a 350 Triumph I not sure how much drama I am getting from my 500's. Both my T100c and the grumph with the T100c engine are really pleasant. Very easy to start, one on points the other electronic ignition. Is it the Daytona (R) engines which were a bit more of a drama?

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                            • #15
                              My thought was from a cost perspective really, that the T100 motor would be perceived as being more desirable, therefore would fetch more than a standard 3TA engine when one went to buy one. I am sure that the cost of converting a 3TA to a 500, given the list of required changes which Stuart itemised, would be more than buying a 500 to start with, so the overboring of the 350 to 400 seemed an interesting variant. I don't think I would be overwhelmed by the power of the 500 (!), and am pretty sure a 350 wouldn't have much more poke than a decent 32/34A motor, so maybe not worth the bother, taking into account extra weight etc. I imagine the Daytona engine makes the power delivery of the 500 more peaky, so less suited to trials or trail riding. Interestingly, I have noticed that for pure trials work the 350, or 400 version, seems more popular than the 500. As you quite rightly said previously Tony, horses for courses. My intended use would be more like yours.
                              Ian
                              Last edited by IanCordes; 07/04/2017, 01:50 PM.

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