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Main tank is 3.4 USgal.



Main tank per the Triumph Workshop Manual specs is 16.6 liters or 4.38 US Gallons or 3.65 Imperial Gallons.

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i am getting 38 to 40 miles



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i have just put in 15 pound ,worth of juice



Your location is empty in your profile so I can only assume you're in the British Isles somewhere based on the monetary unit and general membership of this site, yet you mention number of miles driven not kilometers. Are we talking Imperial or US gallons? Kilometers or Miles?

Maybe we're mixing measuring systems and coming up with bogus numbers?

Regards,

Tom