Dr Evo problem ( ? )

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  • #783427

    Ben Dover
    Topic starter
    Berichten: 2

    Hello , I am an old geezer , who rides a motorcycle , but I also have five different Piaggio two wheelers . Hell , I may buy a three wheeler too ( MP3 ) , if the price is right . It was year 1995 , when  I bought my single speed Ciao . I ride it mainly at winter time  , when trips do not exceed 10 kilometers . I like “less is more” attitude of  the Ciao . My Ciao do not have power enough , when there is headwind , so I decided to fit a DR evo 43 mm cylinder . Crankshaft is with 10 mm piston pin and the needle bearing is 12,7 mm wide ( 10 , 14 , 12,7 ) . However , the space in the piston for needle bearing is 6 mm wider . This means needle bearing can move sideways too much . In my experience , this can not be right . Does anybody know , what is wrong ? Any help would be greatly appreciated .P1070203

    #783440

    dennis84
    Bijdrager
    Berichten: 43

    This is a common problem with all DR-pistons.  I’ve experienced the same issue and began searching for a “wider” bearing. Ordered one from Aliexpress but when it arrived it had exact the same measurement as you mentioned above. (besides very crappy quality) A wider one simply does not exist!

    Filling up the gap around the bearing isn’t a good idea either, with 8.000 rpm it will somehow start to eat away the relatively soft aluminium of the piston.

    There are hundreds, if not thousands DR-cylinders being installed and with nobody complaining about this issue, I decided to install it rightaway using a Malossi bearing. Those are better quality than the one in your picture, and the needles are slightly wider, making it more difficult to eventually fall through… My speedengine with DR-evo is still running fine for about 400km’s. Thats’s not very much, but it runs smooth without any strange sounds/ticking.

    #783448

    niek1992
    Bijdrager
    Berichten: 1593

    I have never seen this type of needle-bearing being shipped with a DRevo before, but i only bought one new once and that is almost 10 years ago. The needle-bearings i used to use where the DMP bearings that have the same dimensions but look a bit tougher.

    I do want to mention that all but one of the DRevo pistons i had, had problems with the pistonrings making noises when revved. The rings had a fraction of a milimeter of play in the grooves where they should be mounted. After 500+km the noise went away (presumably after carbon deposits fitted the ring(s) even tighter).

    I’ve seen @ritze using two small pieces of garden hose that fitted perfectly over the piston pin. I don’t recall exactly if this DIY-fix was able to hold up the thousands of KM’s he made on that DRevo, but it’s worth to check out his perso to look for comments about this. He made it quite tight in there, so the needle-bearing wasn’t able to move much (and thus wasn’t allowed to eat away at the rubber).

     

    #783451

    ritze
    Bijdrager
    Berichten: 3406

    Yeah got the same issue with it and I use to put 2 pieces of thick gas line (rubber) over the pin, so it sits with a bit of clearance in between te piston and bearing. That went okay for at least 500km
    I think its in my perso somwhere

    De budget beun tjoener: geen geld is te duur of het werkt nog niet
    Link naar Mijn collectie / Projecten.
    #783453

    ritze
    Bijdrager
    Berichten: 3406

    RiTzE perso.

    Check half way down page 27

    • Deze reactie is gewijzigd 3 weken, 2 dagen geleden door ritze.
    De budget beun tjoener: geen geld is te duur of het werkt nog niet
    Link naar Mijn collectie / Projecten.
    #783459

    Ben Dover
    Topic starter
    Berichten: 2

    Thanks for the comments , it is nice to know , that I am not alone with this so called problem . Main question is why DR made piston this way  🙄  . I simply can not accept , that needles are partially in the air and therefore connecting rod is stressed either left or right side . So , I am following Ritze’s idea and putting stuff around bearing . I happen to have a new Tomos connecting rod with 10 mm bush in the small end . I will take that bush away and cut two 3 mm wide slices of it . These brass “washers” go around needle bearing . If there comes some problems in the future , I will report it here .
    I must some day read that Ritze´s personal page , it seems interesting , even though G translator is not perfect  🙂 ,

    #783474

    ritze
    Bijdrager
    Berichten: 3406

    A brass spacer would be perfect., I just put something there to get rid of a sound that it made, and it helped a lot.
    The thing I am most proud of in my perso is a liquid cooled Dr Evo on a reedvalve 🙂

    De budget beun tjoener: geen geld is te duur of het werkt nog niet
    Link naar Mijn collectie / Projecten.
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