Jet sizes after new rebore



  • So I've just redone the top end on my DTR project went for a 58.40mm rebore so now it's installed I'm wondering if I'll need to re-jet the carb or will the standerd jets be ok? The bike fires up first kick but dies or bogs down when being revved so I'm guessing it's due to the bigger bore and not getting enough fuel? When I took the spark plug out seemed to be fouled a little bit with oil .Anyone know the best jet size ? Thanks



  • It's a minor minor increase in size.

    A quick test to see if it's fueling, use a higher octane. Or use an Octane booster.

    If the problem goes away then you know the Fuel is too lean. If it's exacerbated, then there is too much fuel.

    Plug chop will tell you if the fuelling is off too!

    I know that for whatever reason, a forged piston can make you need to go up a few jet sizes.



  • @Calum Thanks 😃