Barrel interchangeability



  • Hi all I'm new here and starting to learn all about DT125s.

    The story: My Swiss girlfriend owns a 1997 model DT125 with power valve and electric start. Earlier this year she rode it from her home to western Russia. Unfortunately she had two engine seizures towards the end of the trip and the bike is now being stored in the Ukraine. The bike has great sentimental value to her so we plan to ride down on my bike next year with enough spares to rebuild it so she can ride it home.

    The questions
    Question 1: Are all LC powervalve barrels interchangeable or are there differences between model years that I need to be aware of when buying one?
    Question 2: I'll obviously take all the gaskets required to change the barrel over but are there any other parts which you would recommend I take (eg little end bearing)
    Question 3: Anything DT specific I should watch out when buying replacement barrel and piston?

    Many thanks in advance.



  • That's very odd for the engine to seize.

    Something clearly isn't right as these engines are more than reliable.

    The1997 DT is not an LC and is a DTR.

    So you are looking for barrels coded 3MB000 or 3MB000P.

    The bike was restricted for learner legal riders, I.E. restricted to 11Kw power. As such, you only got a powervalve model if you could prove you had a license.

    Therefore not all cylinders will have the powervalve, but the valve from the 3MB is interchangeable with barrels that used the blanking plate.

    To my mind, the engine has something wrong. Either the fueling is incorrect, the bottom end is worn or the top end is worn.

    Fitting a new top end could result in the bike seizing again due to one of the other factors. So be sure to sort it out before doing it.

    Otherwise, once run in, the engine should see you plenty of miles with the right oils. 10K+



  • Hi, I have a freshly rebored 3MB00 barrel with a new Mitaka piston kit and a new genuine Yamaha little end bearing. Also have a mint like brand new 3MB head only done 300 miles from new and very sought after head. Also have a new Athena head gasket thats been altered to suit the new bore size and a new NGK R plug along with stainless domed nuts and washers for the head. If interested will post some photos for you, also have a modified powervalve to suit the new bore that is virtualy brand new.
    All the parts are matched together and complete ready to fit. If on a budget I have a
    used 3MB00 barrel in good condition with new rings fitted and a used 3BN head.



  • I would be interested in one of the 3mb heads, send me a pm if your OK with that. Ta



  • Skim the head and barrel before you leave, it's the one thing that WILL let you down on a DTR, even if it's not visibly warped it will leak from the gasket, the surfaces need to be absolutely perfect.