Engine Trouble Mechanical error with chain and sprocket link-up.

Discussion in '2-Stroke Engines' started by axlmk, Dec 1, 2015.

  1. axlmk

    axlmk New Member

    I just recently replaced my 49cc engine with an 80cc engine, and after attaching the engine, chain, and all the other bits, I went to start it up--but before then, there was still some clanking with the chain + engine sprocket. It started out seemingly alright (apart from not idling when I pulled the clutch in for some reason), and then a bit of a ways down the street the chain really caught I guess and snapped in half. I haven't the foggiest clue what could be causing this. I tried two different chains and they've both had a ton of clanking with the engine-sprocket.

    What could be causing this? I didn't have the issue at all with my 49cc engine.

  2. crassius

    crassius Well-Known Member

    look at how teeth fit on drive sprocket - teeth may be larger than before - it so, either grind or file teeth, or just swap in the old sprocket

    note that chain may also rub a bit on the cover which can be cut out a bit for extra clearance
  3. aquielisunari

    aquielisunari Member

    Some clanking prior to starting? Sounds as if the chain is misaligned, either because of the position of the engine, sprocket(possibly not concentric) or the wheel. All engines are not exactly the same. It sounds as if the chain is getting caught on the engine, to the right of the sprocket or on the sprocket cover. Sorry I don't know what to call it but I would take off the sprocket cover and see if there is some scarring or chips anywhere around the sprocket or on the inside cover. With the clutch engaged I would see where the chain is in relation to the sprocket. It may be misaligned. It may look fine when slack but fully engaged and on power it gets tighter and may show its true colors. Make sure your master link is right. The first piece connects the links, the second piece goes on and finally the clip is snapped in place with a pair of needle nose pliers. This should of course be facing you and the closed end of the clip should be facing towards the direction of travel of the chain. Make sure you have 1/2" of play in your chain. When you engage your clutch that play is useful because if it doesn't have it it could snap your chain. This is all basic info but it might help. I hope you get this problem fixed.