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748 748 Boggy On Low Revs

Discussion in '748 / 916 / 996 / 998' started by Nick Hemmings, Jul 3, 2026 at 8:06 PM.

  1. Ive just bought a 2002 748s with an 853 conversion and when we went to look at it he told us its done 100 miles in the last three years. Too late then Ive seen and heard it, so obviously HAD to buy it.
    At first it was really bogging and hesitant everywhere now after 60 miles it feels a bit better but still reluctant to pull off without a handful of revs and slip of the clutch.
    Ive put a tank of Shell super in as I don't know how old the fuel was and will look for an injector cleaner fuel additive tomorrow.
    Any other tips?
     
  2. When was fuel filter last changed and how long was that old fuel sat in tank for?
     
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  3. Id start with fuel delivery side of things first and take it from there
     
  4. Standard for my 748SPS at low revs.
     
  5. This might be a silly question but you have had one before haven’t you ? It’s always necessary to give it >3k revs as you slip the clutch home.
     
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    • Agree Agree x 1
  6. As above. OR maybe someone has got the gearing (sprocket sizes) a bit too high, thinking an 848 would pull it!
    My SPS 1st gear has always seemed a bit high even with the original sprocket sizes. But once it's rolling, its just perfect.
     
  7. I agree with above. Not much throttle response below 4000rpm. Could be bad fuel? Lowering gearing can help. I never rode an 853 conversion, so could not say.
     
  8. Personally I wouldn't bother with the 'additive'. Injectors generally either work or they don't. Initially I'd be looking for split fuel hose(s) and replacing the fuel filter, pita job but well documented on here. Chances are it's been neglected and as it's been sat for three years there may well be a load of crap at the bottom of the tank, water ingress E10 retention, yuk.
    Good clean and inspection first Sir, if I may.
     
    #8 Greyman, Jul 4, 2026 at 8:41 AM
    Last edited: Jul 4, 2026 at 8:47 AM
  9. Magneti Marrelli/ Weber IW724 injectors aren't the best , they spit fuel like a cabourettor,rather than spraying it.
     
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