Engine Trouble grubee crank case stripped? whatt?

Discussion in '2-Stroke Engines' started by jatgm1, Apr 24, 2016.

  1. jatgm1

    jatgm1 Member

    i recently finished my first gas powe- ahem, "pedal assisted" bicycle, it uses a grubee skyhawk engine that has a tilted spark plug on the top, so i think its a newer model engine, and a specialized hardrock frame. however i am having issues with it. i noticed that the crank case, the part where the clutch arm is located, when i tighten the bolts (yes, i replaced the screws with bolts of the same size because the original screws heads A] stripped and B] are clearly made of the worst material i have ever seen) it feels like the crank case is literally starting to strip. in fact, the entire crank case feels like its made from some combination of plastic and metal. is there any way i can get a crank case thats made of a higher quality material? the "manic mechanic" sprocket adapter i have on my rear tire is made of a nice high quality cnc aluminum. i know expecting that much is comical for such a cheap price, however is there anywhere that sells actual high quality parts for these engines? and no i don't want friction drive. thank you for your input!
    -tom
     

  2. crassius

    crassius Well-Known Member

    nope, they are all the same and work well if one doesn't tear them up - I'd suggest getting a torque wrench before making things worse - 6 to 8 lb is plenty for 6mm bolts
     
  3. jatgm1

    jatgm1 Member

    is there a way i can open up the crank case, make a hole the size of a bolt, tack weld or something the bolt to the inside of the crank case so it wont strip the case and could grip the bolt and press against the case? also, one of the bolts fell off onto the road while i was riding once, the reason why i tightened them a bit more. and seriously, their okay for the price, but i really wouldn't consider any of these engines as something that necessarily "works well" lol. and it would suprise me quite allot to find that there is no company that machines higher quality crank case blocks and charges more money, i mean, everything conceivable exists on the internet somewhere.
     
  4. crassius

    crassius Well-Known Member

    no idea what that bolt would be for - a pic of where you need it would be good

    no amount of tightening will make the motor stretch to fit the frame - mounts must sit tight in frame before bolts are ever snugged to hold it there
     
  5. jatgm1

    jatgm1 Member

    ? mounts? the mounts are fine. im speaking of the three bolts on the left hand side holding the clutch cover thing on.
     
  6. jatgm1

    jatgm1 Member

    the clutch is retardedly heavy. i assumed this is why the bolt rattled out and that it was a good idea to tighten it well.
     
  7. crassius

    crassius Well-Known Member

    more than 8 years running repair shop for these & never heard of problem like this

    are you sure that replacement bolts were 6x1.0? do the heads fit nicely in the cutaways in the cover? the longer bolt in upper right hole passes thru so that you can put a nut on the end of it to lock it down better

    something is wrong here, as this doesn't happen to anyone else
     
  8. jatgm1

    jatgm1 Member

    no they do not fit in the holes, they have washers and push down on the plate.
     
  9. crassius

    crassius Well-Known Member

    you can order some that fit better, though some of the allen head sets need to have the heads shaved a bit to fit nicely (chuck them into drill press and touch the heads a bit with a file)
     
  10. jatgm1

    jatgm1 Member

    that could be helpful, but do they sell any engine blocks that are made of steel or higher grade aluminum somewhere? it would seem to me that the poor quality engine block is the root of the trouble, these engines seem quite popular, there must be a reputable seller of high quality parts somewhere.
     
  11. Steve Best

    Steve Best Active Member

    Hmmm, my Grubee came with good quality Allen Head bolts.
    Crassius is right, tightened (torqued) properly, the clutch cover has some of the least problem bolts.
    Under tight they fall out. Over tighten them and you strip the case. You need a torque wrench.
    The right bolts should fit down in the holes, not sit on washers over the hole. The washer loses tension.
    If you are using hex bolts over washers over the counterbored holes I can understand you having problems.
    Some grease on the clutch shaft and no cable mounted spring will have the clutch pull in easier.

    The case is slightly softer than most Japanese engines, but I have hundreds of miles on my Grubee, no problems.

    Steve
     
  12. Rizz

    Rizz Guest

    I've been looking everywhere for the sizes of the bolts so I can find them at Ace Hardware. Do you have the sizes of the three clutch cover bolts?
     
Loading...