Thruxton 1200s Fitting 2021 Speed Twin Engine

Discussion in 'Triumph General Discussion' started by andy-gsxr, Dec 16, 2024.

  1. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
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    Lincolnshire
    #1 andy-gsxr, Dec 16, 2024
    Last edited: Dec 24, 2024
    Have 2016 Thruxton 1200s done few miles 55k but have acquired 2021 low milage 5k Speed Twin engine in near new cosmetic condition complete with throttle body and injectors . Not sure if its later higher power engine but think it maybe as it has a breather on cam cover like on later engine (mine has no breather on cam cover ) . Any idea of any problems with engine swap , was going to use Speed Twin throttle body /injectors as same part numbers on all 1200 twins HAH9840 engine number " if anyone can tell what engine I have ? "
    Just removed cam cover to check clearances noticed cam cover breather goes through holes on head so maybe wise to keep this cover on , anyone any idea were this top engine breather goes on the later engine , mine has only breather on crankcase to airbox
     
  2. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    Gosh this is not straightforward, an awful lot needs changing, the biggest issue is engine mounting, the 2 are different, wiring, air box, drive chain re alignment etc etc etc, there is so much to change over, and you need good skills and equipment to do the work, it is costly and time consuming.
     
  3. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
    1
    3
    Lincolnshire
    #3 andy-gsxr, Dec 24, 2024
    Last edited: Dec 24, 2024
    They are exactly the same engine Thruxton 1200 and speed twin 1200 are basically the same bike , just the cosmetics are different . Talking to guy on Youtube he dropped speed twin engine in a Bobber he even flashed the Thruxton map on Bobber . There is a HP 1200 and HT 1200 the HP is the Thruxton /Speed twin , HT is T120 and Bobber only difference is lighter crank lower compression . I know the engine will drop straight in my Thruxton and run but only slight issue I have is it been 2021 engine , it maybe the higher power engine , higher compression /different cam profile . Just wondering how my fuel map will work with it , may need dyno and remap . Higher power engine was introduced in 2021 when Speed Twin got USD forks Radial calipers but they were still selling earlier Speed Twin in 2021 . If its later engine be interesting to Dyno see how engine performs not constrained with the EU5 ECU
     
  4. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
    1
    3
    Lincolnshire
    #4 andy-gsxr, Dec 24, 2024
    Last edited: Dec 24, 2024
    Its straight swap as Speed twin/ Thruxton 1200 are basically the same bike with same engine both use the same Thruxton 1200 engine . But not sure about setup (fuel map ) if its later engine with higher compression different cam cam , if its the pre 2021 engine then engine will be identical to mine (black cases though ) Even the throttle bodies are the same its just that Speed twin doesn't have dummy float bowl and carb slide fitted like rest of Bonneville 1200's . Sorry just realized repeated this on here
     
  5. Iceman

    Iceman Crème de la Crème

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    I wish you the best of luck with the project.
     
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  6. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
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    3
    Lincolnshire
    Thanks but not really a project just simple engine out and back in again as the Thruxton and Speed Twin share same engine . As far as I know the Speed Twin engine after 2021 is exactly the same as Thruxton RS just with different fuel map . I'm just after finding out if my engine is the later engine ie like RS engine if so what fuel map should I use
     
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  7. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
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    Lincolnshire
    Sorry but don't see any of these issues with the chain alignment , mountings , wiring ect as the Thruxton and Speed twin share same engine unless you think I'm fitting the pre unit 1950's speed twin 500 cc , now that would be a project
     
  8. Iceman

    Iceman Crème de la Crème

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    Now the latter would be a straightforward project, as said I wish you the best of luck.
     
  9. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
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    Lincolnshire
    Been on Triumph Rat forum my speed twin engine is the EU5 engine and only mechanical alteration is blanking off the air admission valve . The engine will drop straight in exactly as my old Thruxton engine would . May need a re map or copy n past EU5 map as my older ECU won't accepts EU5 map directly
     
  10. Iceman

    Iceman Crème de la Crème

    Apr 19, 2020
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    As I said I genuinely wish you the best of luck, there are differences in the 2 machines, as helpful as I like to be, unfortunately I don't have time at present to put up all details of these differences between the two, these are not modular bikes as used to be the case in the earlier days of Triumph, however I hope you work it all out, don't however get side-tracked on just the engine mounting, and if you doubt what I say give Triumph technical an e mail, they will respond fairly quickly to your enquiry. Ride safe all from an ageing Rocker.
     
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  11. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
    1
    3
    Lincolnshire
    Yes I well aware of the difference's on this engine as its EU 5 engine it has a lighter crankshaft , different cam profile lighter clutch lighter alternator rotor and air admission valve (that can be removed ) . Physically all the water cooled twins are all exactly the same even the 900 although it has single throttle body . If it had been a EU4 speed twin engine then both my Thruxton 1200 and Speed twin are identical engines . You can swap engines between T120 , Bobber , Thruxton , Speed Twin , scrambler 1200 , friend of mine dropped Speed Twin in a bobber the only issue was he couldn't run the ST ECU so had to copy ST map onto bobber ECU . Actually the Thruxton and Speed twin bikes are pretty much same bike even the ECU's swap between them ok other Bonneville's differ slightly due to only 2 ride modes Bike run ok on Bobber fuel map but it didn't take advantage of the ST engine . As I will state again the only issue I'm concerned with is how this engine will perform on my Thruxton fuel map . They also share same throttle body and injectors , I'm currently running my Thruxton with T120 injectors Throttle body (same part numbers ) Anyway thanks for your interest ride safe
     
  12. andy-gsxr

    andy-gsxr New Member

    Jul 27, 2023
    1
    3
    Lincolnshire
    #12 andy-gsxr, Dec 31, 2024
    Last edited: Dec 31, 2024
    Yes I well aware of the difference's on this engine as its EU 5 engine it has a lighter crankshaft , different cam profile lighter clutch lighter alternator rotor and air admission valve (that can be removed ) . Physically all the water cooled twins are all exactly the same even the 900 although it has single throttle body . If it had been a EU4 speed twin engine then both my Thruxton 1200 and Speed twin are identical engines . You can swap engines between T120 , Bobber , Thruxton , Speed Twin , scrambler 1200 , friend of mine dropped Speed Twin in a bobber the only issue was he couldn't run the ST ECU so had to copy ST map onto bobber ECU bike run ok on Bobber fuel map but it didn't take advantage of the ST engine . Actually the Thruxton and Speed twin bikes are pretty much same bike even the ECU's swap ok ,virtually any part can be swapped between between ST and Thruxton . As I will state again the only issue I'm concerned with is how this engine will perform on my Thruxton fuel map . They also share same throttle body and injectors , I'm currently running my Thruxton with T120 injectors Throttle body (same part numbers ) Anyway thanks for your interest ride safe will update when start on this but wont be for quite a while as busy with other stuff
     
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