Loud pop/crack/bang from lifan 125

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Because it sounds difrent to an identical engine that runs, whole cam shaft area sounds squeeky, and as I spin the flywheel forward the cam chain keeps slapping the engine cast where it comes loose at the bottom of the cam sprocket. It shouldn't be doing that because the identical engine dose not do this, it feels smooth when I turn the flywheel like what turning the flywheel on my bike used to feel like but now it dose this? So obviously somthing is wrong. And No they Have nothing in them. I have another lifan 1pf52 crank case in the shed that rolls smooth, but it needs to be split and redone with new gaskets or else I would just use it. I'll get the stator off and have a look in there as I roll it over, ive already had a a bit of a suss but I can't see any difrence between the two, besides mine seems f'd and it rolls smooth, mabey I'll find somthing after I drill stator off
 
did you refit the timing chain roller in the side of the cylinder when you reassembled the engine?
maybe one of your other rollers has fallen apart ?

4stroke_timingChainGuideRoller_logo.jpg


cam-chainchain-tensioner_bighu0070e3404_dad1.gif
 
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I didn't take the barrel off, and they all look fine to me. Put oil in and all back together and this problem now seems fine, but still won't start
 
was there any sludge in the tensioner tube? if so it may have been restricting the oil flow though it
 
Probably because no oil, and didn't want to put oil in tilli fixed it but it was fixed by the oil haha was just me goin a it crazy because it won't start :/ it's getting spark outside the engine .. But if i take the spark plug cap off and kick it over it sounds the same? Just like my brothers bikeif the killswitch was off
 
so when you kick it over there is a spark ?
connect an old plug to the lead and sit the thread of the plug on the head, watch/listen for a spark.

have you tried a different spark plug in it ?
 
I am thinking since I didn't take the head off to install original helicoil that bent the exhaust valve. Possibly stuffed piston rings, From metal shavings like you said could have happened Craig ? Because everything else's fine. And I never took the barrel off to have a look at how the rings / piston held up,if I have no luck troubleshooting all the little stuff (again) haha I will probably take t apart and have a suss :)
 
Just broke another spark plug soil be re doing the helicoil and seein if it works, and il be looking at the bore and piston, rings ect while head is off" il post the results
 
Inlet clearence was way to loose could that be the reson for not starting? And is it okay to do the valve clearences with the head off? And camshaft at TDC (three holes in camshaft in the same spot as cam sprocket that is still on the cam chain at TDC ? I thought that it would be fine. Soi set them, just double cheackin on that. :)
 
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All back together, made a really good gasket and it legit seems perfect! Cam chain is back to perfect duno why, but it dosnt go loose without oil anymore. Still won't run, had some fule leaking into air filter so switched the carb with a newer one I have, and still nothing ? Driving me insane tring t get this thing to start
 
Put a brand new spark plug in and it starts now :) but I have to hold the throttle on the tiniest bit with the choke on and still dosnt run properly, I'm thinking carb problem plus pos spark plug was the problem :) anyone know what could be up with my carnie though? Il start by soaking it over night in somthing not sure what yet gona have a look around. Just dirty use rekin? Or somthing else
 
i think i mentioned it earlier ?
you'll need a #20 Pilot jet to get it revving crisp
 
Fully cleaned the carb and checked jets, float level and needle tip ur still won't start.. Took the new spark plug out and it's black and wet
 
And it's not getting spark anymore witch is strange because everything's all hooked up they way it should be,
 
spray some carby cleaner on the spark plug and refit it.

have you bumped the wiring when you pulled the carby off ?
bad earth maybe ?
kill switch turned on ?

take the air filter off and check the carby slide is sitting close on the bottom of the carby bore too
you might have reassembled it with the slide around the wrong way ?
 
I mean when i am testing for spark with sp out of head and on a bolt it gets no spark, gone over all connections and evrything looks fine
 
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