rebuild success

Discussion in '2-Stroke Engines' started by blue 48, Dec 16, 2012.

  1. blue 48

    blue 48 Member

    Hi guys its been a while.
    After 12 months of fault less riding, my engine finaly took a dump, seized blew rear tyre and threw me off (im ok). Luckily im well equiped at home and was able to build a new engine out of old parts. i upgraded a few things eg, decent seals/bearings and most signifigantly was a speed carb. all i can say is WOW the difference between the speed and NT stock carb performance is wondefull. after years of using the stock NT this speed carb is great .
     

  2. Fabian

    Fabian Well-Known Member

    The laws of physics determine how much air you can move through a 14mm hole. Speed carburettor or NT Carburettor will give similar power if jetted to the optimal air/fuel ratio.

    I have tried a Genuine Dellorto SHA. A clone SHA, the NT carburettor and a Walbro style (twin needle) diaphragm carburettor.
    With all four carburettors jetted optimally, there was no discernible difference in maximum power.
     
  3. jaguar

    jaguar Well-Known Member

    You should try to figure out why it seized so you don't repeat the same mistake.
    possibilities: jetted too lean, air leak, stuck rings, high compression, advanced ignition (ie: stock ignition), restricted exhaust, insufficient oil
     
  4. blue 48

    blue 48 Member

    I know what went wrong the con rod bearings and gudgeon pin bearings failed ive riden this bike for 3 years now, 5 days a week 40km a day average speed 55kmh i think i had a great run out of it. i had other issues but nothing as terminal as this. in all honesty i believe it was gonna happen regardless so im not upset. oh by the way that whole time i didnt use a base gasket just silicone:-/ and it was still hard to seperate them. as for this new motor its brilliant rse crank,rod,piston and bore on the old case with timken main bearings and seals.also a fresh set of gaskets it fired first go and rides beautifuly. these engines are alot simpler than the big ol caterpillar engines i work on. thinking of building another one just for fun.
     
  5. blue 48

    blue 48 Member

    i agree and understand. both were straight out the box un opened. i think it just behaves a bit better for this engine (if todays 40 km ride was anything to go by)
     
  6. jaguar

    jaguar Well-Known Member

    Are you aware that the stock CDI is what causes those bearing failures? It advances the spark too much at anything above 3000 rpm. Click on my signature link and check out the Jaguar CDI to solve that problem.
     
  7. Fabian

    Fabian Well-Known Member

    Jaguar, i agree with you and have your CDI and coil on my bike. It's a great improvement over the standard CDI and the selectable ignition curve options are so useful when playing around with high compression cylinder heads, not to mention the standard low compression cylinder head.

    I haven't had a small end or big end connecting rod bearing failure since using your CDI.
     
  8. jaguar

    jaguar Well-Known Member

    Super! that's what I like to hear.
     
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