2 stroke rebuild

Discussion in '2 smokers' started by drchupachup, Jun 28, 2012.

  1. drchupachup

    drchupachup Thirsty

    Joined:
    Apr 27, 2009
    Oddometer:
    640
    Location:
    N.E Victoria
    Hi All,

    Hope i'm in an appropriate section of the forum.

    I am after a bit of advice on an engine rebuild I am considering taking on.

    The bike is a 2001 DT230 that I bought recently with 5,500kms on the clock.

    Before you ask, after buying the bike I did the following maintenance items as I was planning a ride from Sydney to Wauchope the following weekend,

    • Changed transmission oil
    • Changed coolant
    • Changed air filter
    • Topped up 2T oil reservoir

    Anyway, even after that the engine had a serious malfunction after 960km of riding . It popped on the F3 freeway north of Sydney at about 130km/h in 6th gear. I did hear a slight whine in the minutes leading up to the blow out but didn’t think too much of it. Maybe I should have however what’s done is done.

    At this point I wasn’t sure if I had,

    1. Seized the top end
    2. Bottom end failure
    3. Transmission failure

    Last weekend I gave the bike a wash and dropped/sieved the trans oil and coolant to look for evidence. Coolant level was spec so overheating should not have been the issue. No bits were found in coolant. Trans oil was contaminated with small bits of alloy that I think is casing. It’s worth noting that the trans oil is isolated to the gearbox (I think).

    With this info at hand I gave myself the following options,

    1. Cut my losses, sell the bike as a non runner
    2. Find a 2nd hand replacement engine/bottom end. Not an easy task and risky as the replacement could be shagged
    3. Get engine rebuilt by professional
    4. Rebuild engine myself

    After considering my options and doing the sums I decided to take on the rebuild myself. I have not done this before and realize its not going to be a walk in the park. I’m a cabinet maker by trade which is not related to engines but I do know how to use my hands and realize the importance of tolerances and attention to detail. I have also been maintaining my own bikes and cars for years. I’ve decided to do this as its something I have wanted to do for a while and interested in learning.

    I have read the engine overhaul manual to research which parts, materials and tools I will need.

    With all that out of the way, and if you are still reading this, I have a few questions about the tools that are required and whether these tools are absolutely necessary or if the task can be done without them, just not as easily. These are the tools that I was wondering if I could get away without buying,

    • Piston pin puller
    • Sheave holder for starter clutch rotor
    • Crankcase separating tool
    • Crankshaft installer pot & bolt


    Any suggestions and advice would be much appreciated.


    Cheers


    Luke
    #1
  2. Shocktower

    Shocktower Long timer

    Joined:
    Jul 27, 2009
    Oddometer:
    9,538
    Location:
    Oregon City Orygun
    So first off did you pull the jug and see if it had siezed :ear, I would jump into it and fix it, can't be that bad :rofl
    #2
  3. stainlesscycle

    stainlesscycle Long timer

    Joined:
    Jun 6, 2008
    Oddometer:
    2,330
    Location:
    morgantown, wv
    drain the coolant, pull the top end take a look see.
    #3
  4. ADV8

    ADV8 Taumarunui..Darwin..

    Joined:
    Nov 10, 2007
    Oddometer:
    2,385
    Location:
    North of Sydney.
    Remove whatever cover is over the generator so you can grab the end of the crankshaft. (Up and down won't hurt either to see how that bearing is)
    Wiggle it back and forth that will tell you a lot noise and feel wise,if you are not sure remove the spark plug and put a wooden dowel down the hole so you can feel if the piston is moving when you do the above.
    Two stokes are very simple,if it was making a whine before the 'drama it might be a main bearing.
    #4
  5. ADV8

    ADV8 Taumarunui..Darwin..

    Joined:
    Nov 10, 2007
    Oddometer:
    2,385
    Location:
    North of Sydney.
    What actually happened ?

    [​IMG]
    #5
  6. drchupachup

    drchupachup Thirsty

    Joined:
    Apr 27, 2009
    Oddometer:
    640
    Location:
    N.E Victoria
    I thinks it's Les right?

    I was riding up the hill after the Ourimbah interchange southbound. Was doing about120km/h (maybe a little more) in 6th gear when the rear wheel locked up. I pulled the clutch to stop the lock up but the engine was not completely disengaged. There was still some resistance from the engine. I could not get teh bike in neutral that night.

    Since i got the bike home i have managed to find neutral. The engine does turn but not freely.

    All I have done in terms of diagnosis so far is drain the oil and coolant. I am hoping to get the engine out this weekend and look into it further.

    Thanks heaps for the tips.


    Luke
    #6
  7. ADV8

    ADV8 Taumarunui..Darwin..

    Joined:
    Nov 10, 2007
    Oddometer:
    2,385
    Location:
    North of Sydney.
    SWMBO calls me by other names sometimes. :lol3

    If it was uphill under some load it might have been a seizure or light seizure if it turns with a little resistance now.
    In neutral you could probably feel if it has had a seizure when the crank shaft is rotated by the resistance.
    How is the gear box selection now,say with the spark plug removed and rear wheel off the ground,will it select all gears if the wheel was rotated ?
    Any odd noises from that area. (Including with the clutch lever pulled in)
    #7
  8. drchupachup

    drchupachup Thirsty

    Joined:
    Apr 27, 2009
    Oddometer:
    640
    Location:
    N.E Victoria
    The gearbox selection seems to be ok now but have not ran the engine since the lock up.

    It does make odd noises when wheeling the bike around when in gear, and when the clutch is in. Not so much in neutral but still sounds suss.

    I haven't had the plug out yet, hopefully this weekend.
    #8
  9. ADV8

    ADV8 Taumarunui..Darwin..

    Joined:
    Nov 10, 2007
    Oddometer:
    2,385
    Location:
    North of Sydney.
    I was just curious about the wheel locking up.
    A severe seizure could do that but would have thought in your case the power would have started feeling like it was dropping off as it led up to the locking up even with increased throttle.
    It makes you wonder about the transmission and if the problem is there.
    #9
  10. Harvey Krumpet

    Harvey Krumpet Long timer

    Joined:
    Dec 26, 2011
    Oddometer:
    1,416
    Location:
    The Shaky Isles
    That's what I think, bits of metal in the gearbox oil must be from the gear box.
    #10
  11. drchupachup

    drchupachup Thirsty

    Joined:
    Apr 27, 2009
    Oddometer:
    640
    Location:
    N.E Victoria
    I'm still not convinced its isolated to the gearbox yet either. There are bits of crap coming out of it so i know something has let go in there. I hope it's just that, will find out soon enough.
    #11
  12. anonny

    anonny What could go wrong?

    Joined:
    Mar 20, 2007
    Oddometer:
    6,127
    Location:
    Beautiful Revelstoke BC
    I think you could get away without any of these tools.
    #12
  13. drchupachup

    drchupachup Thirsty

    Joined:
    Apr 27, 2009
    Oddometer:
    640
    Location:
    N.E Victoria
  14. Harvey Krumpet

    Harvey Krumpet Long timer

    Joined:
    Dec 26, 2011
    Oddometer:
    1,416
    Location:
    The Shaky Isles
    Freaky, I was just wondering how you were getting on....

    That looks like a serious weekend of spannering, couldn't see a stereo either. Fingers crossed for the motor.
    #14
  15. drchupachup

    drchupachup Thirsty

    Joined:
    Apr 27, 2009
    Oddometer:
    640
    Location:
    N.E Victoria
    I had my iphone with mini speakers so all good.

    I decided to pull the motor out and reassemble the bike in the parking garage at home. I don't have my own shed anymore so will be inconveniencing my grandfather or uncle by using theirs instead. Figured I was less likely to piss them off too much if i just brought around the engine and left the rest of the bike at home.

    I got my clutch holder and flywheel puller in the mail today so pretty much ready to go now.
    #15